/* ============================================================
   水木橙红军事仿真门户网站 · 设计系统 v2
   配色改为照搬"恒歌科技"官网真实色值（浅灰/白底为主，深色仅用于
   导航/首屏/页脚），取代 v1 自创的深色军事态势配色。
   色值来源：C:\Users\15932\Desktop\恒歌科技源码-视觉参考提取\
             *_files\base.css / style.css（已实际读取提取）
   ============================================================ */

/* ---------- 1. 基础变量 ---------- */
:root {
  /* 内容区配色（浅色系，恒歌真实主色板） */
  --c-bg: #fff;              /* 内容区默认白底，替代原 --c-navy 深色语义 */
  --c-bg-alt: #ECEEF2;       /* 内容区次背景浅灰，恒歌真实主背景色，替代原 --c-steel */
  --c-bg-alt2: #F8F8F8;      /* 更浅的辅助分段色 */
  --c-border: #E1E6F0;       /* 浅灰边框/分割线，替代原 --c-cool-gray 深色语义 */
  --c-text: #3D3D3D;         /* 正文/标题主文字色，恒歌真实正文色，替代原 --c-cool-white 深色语义 */
  --c-text-weak: rgba(61,61,61,.6);
  --c-blue: #2659FF;         /* 恒歌真实主强调色（链接/按钮/高亮） */
  --c-cyan: #53D7E5;         /* 恒歌真实辅助强调色（渐变起点） */
  --c-alert: #af1e28;        /* 恒歌真实警示色（沿用） */

  /* 深色区域专用（仅导航/首屏遮罩/页脚使用，恒歌真实深色值） */
  --c-dark-header: rgba(14,15,18,.8);   /* 恒歌 #header 真实值 */
  --c-dark-footer: #22242B;             /* 恒歌 #foot 真实值 */
  --c-white: #fff;

  /* 品牌渐变（恒歌真实值：linear-gradient(106deg,#53D7E5 0,#2659FF 99%)） */
  --grad-brand: linear-gradient(106deg, #53D7E5 0%, #2659FF 99%);

  /* 字体（恒歌真实字体族） */
  --font-cn: "思源黑体", "苹方", "微软雅黑", Arial, sans-serif;
  --font-en: "Jost-Bold", "思源黑体", sans-serif; /* 恒歌 h3 真实用 Jost-Bold 混排 */

  /* 间距 */
  --pad-section: 5rem;
  --container-max: 1600px;
  --container-pad: 80px;

  /* 过渡 */
  --tr: .5s;
  --tr-slow: 1s;
}

@media (max-width: 1024px) {
  :root { --pad-section: 3.5rem; --container-pad: 40px; }
}
@media (max-width: 768px) {
  :root { --pad-section: 3rem; --container-pad: 20px; }
}

/* ---------- 2. Reset & 基础排版 ---------- */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { font-size: 16px; scroll-behavior: smooth; }
@media (max-width: 1600px) { html { font-size: 15px; } }
@media (max-width: 1024px) { html { font-size: 14px; } }
@media (max-width: 480px)  { html { font-size: 13px; } }

body {
  font-family: var(--font-cn);
  background: var(--c-bg-alt);  /* 恒歌 body{background:#eceef2} 真实值 */
  color: var(--c-text);
  line-height: 1.75;
  overflow-x: hidden;
}

a { text-decoration: none; color: inherit; }
ul, ol { list-style: none; }
img { max-width: 100%; display: block; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }

h1, h2, h3, h4 { font-weight: bold; line-height: normal; color: var(--c-text); }
h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
p  { font-size: 1rem; }
.caption { font-size: .875rem; color: var(--c-text-weak); }

/* ---------- 3. 布局容器 ---------- */
.m {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-pad);
}
.section {
  padding: var(--pad-section) 0;
  position: relative;
}
/* 内容区两种交替背景：均为浅色，恒歌式分段节奏 */
.section--steel   { background: var(--c-bg-alt); color: var(--c-text); }
.section--navy    { background: var(--c-bg); color: var(--c-text); }
.section--light   { background: var(--c-bg-alt2); color: var(--c-text); }

.section-head { margin-bottom: 3rem; }
.section-head .eyebrow {
  font-family: var(--font-en);
  letter-spacing: 2px;
  color: var(--c-blue);
  font-size: .875rem;
  text-transform: uppercase;
  display: block;
  margin-bottom: .75rem;
}
.section-head h2 { color: var(--c-text); font-size: 1.875rem; }
.section-head .desc { margin-top: .625rem; max-width: 680px; color: var(--c-text); opacity: .5; font-size: .875rem; }

/* 网格系统 */
.grid { display: grid; gap: 1.5rem; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
.grid-5 { grid-template-columns: repeat(5, 1fr); }
@media (max-width: 1200px) {
  .grid-5 { grid-template-columns: repeat(3, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
  .grid-2, .grid-3, .grid-4, .grid-5 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 480px) {
  .grid-2, .grid-3, .grid-4, .grid-5 { grid-template-columns: 1fr; }
}
.grid-6 { grid-template-columns: repeat(6, 1fr); }
@media (max-width: 1200px) { .grid-6 { grid-template-columns: repeat(3, 1fr); } }
@media (max-width: 768px) { .grid-6 { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 480px) { .grid-6 { grid-template-columns: 1fr; } }

/* ---------- 4. 装饰元素（去掉自创的军事网格/发光效果，改用恒歌式简洁描边面板） ---------- */
.tactical-grid { display: none; } /* 原"态势网格"为自创科幻装饰，恒歌真实视觉无此元素，隐藏 */
.clip-slant { clip-path: none; } /* 原斜切装饰同理去除，保持恒歌矩形分段风格 */
.panel {
  background: var(--c-white);
  border: 1px solid var(--c-border);
}
.glow-edge, .glow-edge--gold { box-shadow: none; } /* 去除自创发光效果 */

/* ---------- 5. 顶部导航（恒歌真实：半透明深色，68px高度） ---------- */
.header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 999;
  background: var(--c-dark-header);
  transition: var(--tr);
}
.header.is-scrolled { background: rgba(14,15,18,.95); }
.header .m { display: flex; align-items: center; justify-content: space-between; height: 68px; transition: var(--tr); }
.header.is-scrolled .m { height: 60px; }

.brand { display: flex; align-items: center; gap: .75rem; }
.brand-cn { font-size: 1.25rem; font-weight: bold; color: #fff; letter-spacing: 1px; }
.brand-en { font-family: var(--font-en); font-size: .7rem; color: var(--c-cyan); letter-spacing: 3px; text-transform: uppercase; }

.nav { display: flex; gap: 2.5rem; height: 100%; }
.nav > li { position: relative; height: 100%; }
.nav > li > a {
    font-size: 1rem; color: #fff; opacity: .8;
    padding: 0; display: flex; align-items: center; height: 100%;
    box-sizing: border-box; transition: var(--tr);
    border-bottom: 2px solid transparent;
  }
.nav > li.active > a {
  opacity: 1; border-bottom-color: var(--c-cyan);
}
.nav > li:hover > a {
  opacity: 1; border-bottom-color: var(--c-cyan);
}
/* 鼠标在导航区域内时，非hover的active项退回默认态，避免"当前页"和"正在悬浮"两个高亮同时出现 */
.nav:hover > li.active:not(:hover) > a {
  opacity: .8; border-bottom-color: transparent;
}
.nav .submenu {
  position: absolute; top: 100%; left: 50%; transform: translateX(-50%);
  background: #fff; border: 1px solid var(--c-border); box-shadow: 0 8px 24px rgba(0,0,0,.12);
  min-width: 220px; padding: .5rem 0; opacity: 0; visibility: hidden;
  transition: var(--tr); border-radius: 6px;
}
.nav > li:hover .submenu { opacity: 1; visibility: visible; }
.nav .submenu a { display: block; padding: .6rem 1.25rem; font-size: .9rem; white-space: nowrap; color: var(--c-text); }
.nav .submenu a:hover { color: var(--c-blue); background: var(--c-bg-alt); }

.header-cta { display: flex; align-items: center; gap: 1rem; }
.header-cta .tel { font-size: 1rem; color: #fff; }

.nav-toggle { display: none; color: #fff; }
@media (max-width: 1024px) {
  .nav { display: none; }
  .nav-toggle { display: block; }
}

/* ---------- 6. 首屏 Hero（图片/视频背景 + 深色遮罩，恒歌真实做法） ---------- */
.hero {
  position: relative; min-height: 100vh; display: flex; align-items: center;
  background-size: cover; background-position: center; overflow: hidden;
  background-color: #1a1a1a;
}
.hero::before {
  content: ""; position: absolute; inset: 0;
  background: linear-gradient(120deg, rgba(14,15,18,.85) 0%, rgba(14,15,18,.55) 45%, rgba(14,15,18,.35) 100%);
  z-index: 1;
}
.hero-inner { position: relative; z-index: 2; padding-top: 68px; width: 100%; }
.hero .eyebrow { font-family: var(--font-en); letter-spacing: 3px; color: var(--c-cyan); font-size: .95rem; margin-bottom: 1.5rem; display: block; text-transform: uppercase; }
.hero-title {
  font-size: clamp(2.25rem, 4.5vw, 4rem); font-weight: bold; max-width: 900px; margin-bottom: 1.5rem;
  color: #fff;
}
.hero-sub { font-size: 1.25rem; color: rgba(255,255,255,.7); max-width: 640px; margin-bottom: 2.5rem; line-height: 1.7; }
.hero-btns { display: flex; gap: 1rem; }

/* 胶囊双按钮：恒歌真实写法 .btnbox{width:15rem;height:3.125rem;border-radius:25px} */
/* 用 grid 的等分 fr 列代替 flex：容器宽度为 max-content 时，两列会一起撑到较宽文案的宽度，保证左右对称且不换行 */
.btnbox { display: grid; grid-auto-flow: column; grid-auto-columns: 1fr; width: max-content; min-width: 15rem; height: 3.125rem; border-radius: 25px; overflow: hidden; background: #fff; border: 1px solid rgba(0,0,0,.2); }
.btnbox a { display: flex; align-items: center; justify-content: center; font-size: .95rem; white-space: nowrap; padding: 0 1.5rem; transition: var(--tr); color: var(--c-text); }
.btnbox a.pri { background: var(--grad-brand); color: #fff; font-weight: bold; }
.btnbox a.pri:hover { opacity: .9; }
.btnbox a.sec:hover { background: var(--c-bg-alt); color: var(--c-blue); }
/* Hero 上使用的按钮组，背景改为半透明白，避免深色区域看不清 */
.hero .btnbox, .page-banner .btnbox { background: rgba(255,255,255,.95); }
@media (max-width: 480px) { .btnbox { width: 100%; height: 3.25rem; } }

.scroll-hint {
  position: absolute; bottom: 2rem; left: 50%; transform: translateX(-50%); z-index: 2;
  width: 20px; height: 20px; border-right: 2px solid #fff; border-bottom: 2px solid #fff;
  transform: translateX(-50%) rotate(45deg); opacity: .7;
  animation: chevron_down 1.6s ease-in-out infinite;
}
@keyframes chevron_down {
  0%, 100% { opacity: .3; margin-top: 0; }
  50% { opacity: .8; margin-top: 10px; }
}

/* 内页 Banner（静态图 + 深色遮罩，标题白色） */
.page-banner {
  position: relative; padding-top: 68px; min-height: 340px; display: flex; align-items: center;
  background-size: cover; background-position: center; background-color: #1a1a1a;
}
.page-banner::before {
  content: ""; position: absolute; inset: 0;
  background: linear-gradient(120deg, rgba(14,15,18,.82) 0%, rgba(14,15,18,.55) 60%, rgba(14,15,18,.35) 100%);
}
.page-banner-inner { position: relative; z-index: 2; }
.page-banner h1 { font-size: clamp(2rem, 3.5vw, 3rem); margin-bottom: .75rem; color: #fff; }
.page-banner .sub { color: rgba(255,255,255,.7); font-size: 1.125rem; max-width: 620px; }
.breadcrumb { font-size: .875rem; color: rgba(255,255,255,.6); margin-bottom: 1.25rem; }
.breadcrumb a:hover { color: var(--c-cyan); }

/* ---------- 7. 卡片组件（恒歌真实：白底、小圆角4px、hover图片轻微放大） ---------- */
.card {
  background: #fff;
  border: 1px solid var(--c-border);
  border-radius: 4px;
  overflow: hidden;
  transition: var(--tr);
  position: relative;
}
.card:hover { box-shadow: 0 8px 24px rgba(0,0,0,.1); transform: translateY(-4px); }
.card .card-img { height: 200px; overflow: hidden; position: relative; background: var(--c-bg-alt); }
.card .card-img img { width: 100%; height: 100%; object-fit: cover; transition: var(--tr-slow); }
.card:hover .card-img img { transform: scale(1.06); }
.card .card-body { padding: 1.5rem; }
.card .card-body .tag { display: inline-block; margin-bottom: .75rem; }
.card .card-title { font-size: 1.125rem; margin-bottom: .5rem; color: var(--c-text);
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.card .card-desc { font-size: .9rem; color: var(--c-text-weak); line-height: 1.6; }

.tag {
  border-radius: 15px; border: 1px solid var(--c-blue); color: var(--c-blue);
  padding: 2px 12px; font-size: .8rem; display: inline-block;
}
.tag--gold { border-color: #5b5349; color: #5b5349; } /* 沿用恒歌页面出现过的暖灰强调色，替代原哑金 */
.tag--alert { border-color: var(--c-alert); color: var(--c-alert); }

/* 架构图专用容器：完整展示不裁剪，按图片真实比例给高度，点击可放大查看细节 */
.diagram-box {
  background: #fff; border: 1px solid var(--c-border); border-radius: 4px;
  padding: 1.5rem; cursor: zoom-in; position: relative; overflow: hidden;
}
.diagram-box img { width: 100%; height: auto; object-fit: contain; display: block; }

/* 架构图图文两栏：文字窄、图片宽的变体（左侧文字说明约占1/3，右侧架构图约占2/3），
   用于图片本身信息密度高、需要更大展示空间的场景（如天翼架构图） */
.grid-arch { grid-template-columns: .6fr 2fr; }
@media (max-width: 900px) {
  .grid-arch { grid-template-columns: 1fr; }
}

/* 图片放大灯箱 */
.lightbox {
  position: fixed; inset: 0; z-index: 1000; background: rgba(14,15,18,.92);
  display: none; align-items: center; justify-content: center; padding: 3rem; cursor: zoom-out;
}
.lightbox.is-open { display: flex; }
.lightbox img { max-width: 96vw; max-height: 90vh; object-fit: contain; box-shadow: 0 20px 60px rgba(0,0,0,.5); }
.lightbox .lightbox-close {
  position: absolute; top: 1.5rem; right: 2rem; color: #fff; font-size: 2rem; line-height: 1; opacity: .8;
}
.lightbox .lightbox-close:hover { opacity: 1; }

/* 产品矩阵卡片（首页五产品） */
.product-card { text-align: center; padding: 2.5rem 1.5rem; }
.product-card .icon-wrap {
  width: 92px; height: 92px; margin: 0 auto 1.25rem;
  display: flex; align-items: center; justify-content: center;
}
.product-card .icon-wrap img { width: 100%; height: 100%; object-fit: contain; }
.product-card .en-name { font-family: var(--font-en); letter-spacing: 2px; font-size: .75rem; color: var(--c-text-weak); margin-bottom: .5rem; text-transform: uppercase; }
.product-card h3 { color: var(--c-text); margin-bottom: .75rem; }
.product-card .position { font-size: .9rem; color: var(--c-text-weak); margin-bottom: 1.25rem; min-height: 3.2em; }
.product-card .dim { font-size: .8rem; color: var(--product-color, var(--c-blue)); font-weight: bold; }

/* ---------- 8. 技术底座分层模块（横向四栏，编号+标题常驻显示，箭头串联表达层级递进） ---------- */
.foundation-stack { display: flex; align-items: stretch; }
.foundation-layer {
  flex: 1; position: relative; background: var(--c-bg); border: 1px solid var(--c-border); border-radius: 6px;
  padding: 2rem 1.5rem; transition: var(--tr);
}
.foundation-layer:hover { border-color: var(--c-blue); box-shadow: 0 8px 24px rgba(0,0,0,.08); transform: translateY(-4px); }
.foundation-layer:not(:last-child) { margin-right: 2.5rem; }
.foundation-layer:not(:last-child)::after {
  content: ""; position: absolute; top: 50%; right: -2rem; transform: translateY(-50%);
  width: 0; height: 0; border-top: 7px solid transparent; border-bottom: 7px solid transparent; border-left: 10px solid var(--c-border);
}
.foundation-num {
  font-family: var(--font-en); font-size: 2rem; font-weight: bold; color: var(--c-blue); opacity: .35; line-height: 1; margin-bottom: 1rem;
}
.foundation-body h4 { font-size: 1.125rem; color: var(--c-text); margin-bottom: .75rem; }
.foundation-body p { font-size: .875rem; color: var(--c-text-weak); line-height: 1.7; }
@media (max-width: 1024px) {
  .foundation-stack { flex-direction: column; gap: 1rem; }
  .foundation-layer:not(:last-child) { margin-right: 0; }
  .foundation-layer:not(:last-child)::after {
    top: auto; right: 50%; bottom: -1.5rem; left: auto; transform: translateX(50%) rotate(90deg);
  }
}

/* ---------- 9. 编号功能清单 ---------- */
.feature-list { display: flex; flex-direction: column; gap: 1.25rem; }
.feature-list li {
  display: flex; gap: 1.25rem; align-items: flex-start;
  padding: 1.25rem 0; border-bottom: 1px solid var(--c-border);
}
.feature-list .num {
  font-family: var(--font-en); font-size: 1.75rem; font-weight: bold; color: var(--c-blue);
  min-width: 2.5rem; line-height: 1;
}
.feature-list .content .title { font-size: 1.05rem; color: var(--c-text); margin-bottom: .35rem; font-weight: bold; }
.feature-list .content .desc { font-size: .9rem; color: var(--c-text-weak); }

/* ---------- 10. KPI 数据条 ---------- */
.kpi-strip { display: grid; grid-template-columns: repeat(4, 1fr); gap: 2.5rem; }
.kpi-item { min-width: 0; text-align: left; border-left: 2px solid var(--c-blue); padding-left: 1.25rem; }
@media (max-width: 768px) { .kpi-strip { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 480px) { .kpi-strip { grid-template-columns: 1fr; } }
.kpi-item .num {
  font-family: var(--font-en); font-size: 2.75rem; font-weight: bold; color: var(--c-blue); line-height: 1;
  display: flex; align-items: baseline; gap: .25rem;
}
.kpi-item .num .unit { font-size: 1.1rem; color: var(--c-text); opacity: .7; font-family: var(--font-cn); }
.kpi-item .label { font-size: .875rem; color: var(--c-text-weak); margin-top: .5rem; }

/* ---------- 11. 表格（用于指标对照/验收数据） ---------- */
.data-table { width: 100%; border-collapse: collapse; margin: 1.5rem 0; }
.data-table th, .data-table td {
  padding: .9rem 1.25rem; border: 1px solid var(--c-border); font-size: .9rem; text-align: left;
}
.data-table th { background: var(--c-bg-alt); color: var(--c-text); font-weight: bold; }
.data-table td { background: #fff; color: var(--c-text); }

/* ---------- 12. 按钮 ---------- */
.btn { display: inline-flex; align-items: center; justify-content: center; padding: .9rem 2rem; border-radius: 999px; font-size: .95rem; transition: var(--tr); }
.btn-primary { background: var(--grad-brand); color: #fff; font-weight: bold; }
.btn-primary:hover { opacity: .9; }
.btn-outline { border: 1px solid var(--c-border); color: var(--c-text); }
.btn-outline:hover { background: var(--c-bg-alt); border-color: var(--c-blue); color: var(--c-blue); }

/* ---------- 13. 标签墙 / Logo 墙 ---------- */
.tag-wall { display: flex; flex-wrap: wrap; gap: .75rem; }
.tag-wall .tag { padding: .5rem 1.25rem; }

/* ---------- 14. 风险提示条 ---------- */
.risk-note {
  border-left: 3px solid var(--c-alert); background: rgba(175,30,40,.05);
  padding: 1rem 1.5rem; font-size: .875rem; color: var(--c-text); margin: 1.5rem 0; border-radius: 0 4px 4px 0;
}
.risk-note b { color: var(--c-alert); }

/* ---------- 15. 页脚（恒歌真实 #foot{background:#22242B}） ---------- */
.footer { background: var(--c-dark-footer); padding-top: 4rem; }
.footer .m { display: grid; grid-template-columns: 1.5fr 1fr 1fr 1fr 1.2fr; gap: 2rem; padding-bottom: 3rem; }
.footer-brand .brand-cn { font-size: 1.25rem; margin-bottom: .5rem; color: #fff; }
.footer-brand .slogan { font-size: .875rem; color: rgba(255,255,255,.55); margin-top: 1rem; line-height: 1.8; }
.footer-col h4, .footer-contact h4 { font-size: 1rem; color: #fff; margin-bottom: 1.25rem; }
.footer-col a { display: block; font-size: .875rem; color: rgba(255,255,255,.6); margin-bottom: .75rem; transition: var(--tr); }
.footer-col a:hover { color: var(--c-cyan); }
.footer-contact p { font-size: .875rem; color: rgba(255,255,255,.6); margin-bottom: .75rem; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,.08); padding: 1.5rem 0; text-align: center; font-size: .8rem; color: rgba(255,255,255,.4); }
@media (max-width: 1024px) { .footer .m { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 480px) { .footer .m { grid-template-columns: 1fr; } }

/* ---------- 16. AOS 兜底（防止未加载时内容不可见） ---------- */
[data-aos] { opacity: 1; }
.aos-init:not(.aos-animate) { opacity: 0; transition: opacity .6s, transform .6s; }
.aos-init[data-aos="fade-up"]:not(.aos-animate) { transform: translateY(24px); }
.aos-animate { opacity: 1; transform: none; }

/* ---------- 17. 导航改版新增：级联二级菜单（"产品与解决方案" → 悬浮"产品体系"/"解决方案" → 再悬浮展开具体条目） ---------- */
.nav .submenu-cascade { min-width: 150px; }
.submenu-cascade-item { position: relative; }
.submenu-cascade-item > a {
  display: flex; align-items: center; justify-content: flex-start; gap: .5rem;
  width: 100%; box-sizing: border-box;
  padding-right: .9rem;
}
.submenu-cascade-item > a .arrow {
  font-size: .95rem; color: var(--c-text-weak); line-height: 1; font-weight: 700;
  opacity: .85; transform: translateY(-1px); margin-left: auto; padding-left: .75rem;
}
.submenu-cascade-item:hover > a { color: var(--c-blue); background: var(--c-bg-alt); }
/* 第二层菜单不继承 .submenu 基类，避免被 ".nav > li:hover .submenu" 选择器误命中而与一级悬浮同步弹出 */
.submenu-level2 {
  position: absolute; top: -1px; left: calc(100% + 16px); margin-left: 0;
  background: #fff; border: 1px solid var(--c-border); box-shadow: 0 8px 24px rgba(0,0,0,.12);
  min-width: 230px; padding: .5rem 0; opacity: 0; visibility: hidden;
  transition: var(--tr); border-radius: 6px;
}
.submenu-cascade-item:hover > .submenu-level2 { opacity: 1; visibility: visible; }
.submenu-level2 a { display: block; padding: .6rem 1.25rem; font-size: .9rem; white-space: nowrap; color: var(--c-text); }
.submenu-level2 a:hover { color: var(--c-blue); background: var(--c-bg-alt); }

/* ---------- 18. 按钮hover效果对齐恒歌真实实现：默认深灰边框，hover变蓝+浅蓝底，:active铺满渐变 ---------- */
.btn-outline {
  border: 1px solid rgba(61,61,61,.35); color: var(--c-text);
  background: transparent;
}
.btn-outline:hover { background: rgba(38,89,255,.06); border-color: var(--c-blue); color: var(--c-blue); }
.btn-outline:active { background: var(--grad-brand); border-color: transparent; color: #fff; }

/* ---------- 19. 产品阵容小卡片（左图标+右文字，网格排列，首页新版布局） ---------- */
.product-mini-grid { align-items: stretch; }
.product-mini-card {
  display: flex; align-items: flex-start; gap: 1.25rem;
  background: #fff; border: 1px solid var(--c-border); border-radius: 4px;
  padding: 1.75rem 1.5rem; transition: var(--tr);
}
.product-mini-card:hover { box-shadow: 0 8px 24px rgba(0,0,0,.08); transform: translateY(-4px); border-color: var(--c-blue); }
.product-mini-card .mini-icon {
  flex: none; width: 56px; height: 56px; display: flex; align-items: center; justify-content: center;
}
.product-mini-card .mini-icon img { width: 100%; height: 100%; object-fit: contain; }
.product-mini-card .mini-body h3 { font-size: 1.05rem; margin-bottom: .5rem; }
.product-mini-card .mini-body p {
  font-size: .85rem; color: var(--c-text-weak); line-height: 1.7;
  display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden;
}
@media (max-width: 768px) {
  .product-mini-card { padding: 1.5rem 1.25rem; }
}

/* ---------- 20. 媒体中心 tab 切换组件 ---------- */
.media-tabs { display: flex; gap: 1rem; border-bottom: 1px solid var(--c-border); margin-bottom: 2.5rem; flex-wrap: wrap; }
.media-tabs .tab-btn {
  padding: 1rem 0; font-size: 1rem; color: var(--c-text-weak); border-bottom: 2px solid transparent;
  background: none; transition: var(--tr);
}
.media-tabs .tab-btn.active { color: var(--c-blue); border-bottom-color: var(--c-blue); font-weight: bold; }
.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* 资料下载：标签筛选 + 卡片列表 */
.download-filters { display: flex; gap: .75rem; margin-bottom: 2rem; flex-wrap: wrap; }
.download-filters .filter-btn {
  border-radius: 15px; border: 1px solid var(--c-border); color: var(--c-text-weak);
  padding: .4rem 1.1rem; font-size: .85rem; background: none; transition: var(--tr);
}
.download-filters .filter-btn.active { border-color: var(--c-blue); color: var(--c-blue); background: rgba(38,89,255,.06); }
.download-item {
  display: flex; align-items: center; justify-content: space-between; gap: 1rem;
  padding: 1.1rem 1.5rem; border: 1px solid var(--c-border); border-radius: 4px; margin-bottom: .75rem;
  background: #fff; transition: var(--tr);
}
.download-item:hover { border-color: var(--c-blue); box-shadow: 0 4px 16px rgba(0,0,0,.06); }
.download-item .dl-name { font-size: .95rem; color: var(--c-text); }
.download-item .dl-meta { font-size: .8rem; color: var(--c-text-weak); }

/* ---------- 21. "暂无内容"占位卡片：用于新闻动态/资质荣誉/最新动态等素材缺失板块 ---------- */
.placeholder-card {
  border: 1px dashed var(--c-border); border-radius: 4px; padding: 3rem 2rem;
  text-align: center; color: var(--c-text-weak); background: var(--c-bg-alt2);
}
.placeholder-card .ph-icon { font-size: 1.75rem; margin-bottom: .75rem; opacity: .5; }
.placeholder-card .ph-title { font-size: 1rem; color: var(--c-text-weak); margin-bottom: .35rem; }
.placeholder-card .ph-desc { font-size: .85rem; opacity: .8; }

/* ---------- 22. 流程时间线（天枢推演八步 / 天翼装备调度五段，横向排列，两页配色不同以做区分） ---------- */
.process-timeline { display: flex; align-items: stretch; gap: 0; flex-wrap: wrap; }
.process-timeline .pt-step {
  flex: 1; min-width: 150px; position: relative;
  background: var(--c-bg); border: 1px solid var(--c-border); border-radius: 6px;
  padding: 1.5rem 1.25rem; margin-right: 1.25rem; margin-bottom: 1.25rem;
}
.process-timeline .pt-step:last-child { margin-right: 0; }
.process-timeline .pt-step::after {
  content: ""; position: absolute; top: 50%; right: -1.05rem; transform: translateY(-50%);
  width: 0; height: 0; border-top: 6px solid transparent; border-bottom: 6px solid transparent; border-left: 9px solid var(--c-border);
}
.process-timeline .pt-step:last-child::after { display: none; }
.process-timeline .pt-num {
  font-family: var(--font-en); font-size: 1.5rem; font-weight: bold; color: var(--c-blue); opacity: .4; line-height: 1; margin-bottom: .75rem;
}
.process-timeline .pt-title { font-size: .98rem; color: var(--c-text); font-weight: bold; margin-bottom: .4rem; }
.process-timeline .pt-desc { font-size: .8rem; color: var(--c-text-weak); line-height: 1.6; }
@media (max-width: 1024px) {
  .process-timeline .pt-step { flex: 0 0 100%; margin-right: 0; }
  .process-timeline .pt-step::after {
    top: auto; right: 50%; bottom: -1rem; transform: translateX(50%) rotate(90deg);
  }
}
/* 天枢变体：红蓝语义分工——对抗/告警类步骤用警示色边框，平台/控制类保持主蓝 */
.process-timeline--conflict .pt-step.is-conflict { border-color: var(--c-alert); }
.process-timeline--conflict .pt-step.is-conflict .pt-num { color: var(--c-alert); }
.process-timeline--conflict .pt-step.is-conflict::after { border-left-color: var(--c-alert); opacity: .6; }
/* 天翼变体：青蓝/钢蓝色系，与天枢的主蓝区分气质 */
.process-timeline--steel .pt-step { border-color: #C7D6E5; }
.process-timeline--steel .pt-step:hover { border-color: #1F6F8B; }
.process-timeline--steel .pt-num { color: #1F6F8B; }
.process-timeline--steel .pt-step::after { border-left-color: #C7D6E5; }

/* ---------- 23. 天境六大情绪场景卡片矩阵（替代表格，交付状态用色点表达） ---------- */
.emotion-card-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.25rem; }
.emotion-card {
  background: var(--c-bg); border: 1px solid var(--c-border); border-radius: 6px; padding: 1.5rem;
  transition: var(--tr);
}
.emotion-card:hover { box-shadow: 0 8px 24px rgba(0,0,0,.08); transform: translateY(-3px); }
.emotion-card .ec-head { display: flex; align-items: center; justify-content: space-between; margin-bottom: .75rem; }
.emotion-card .ec-name { font-size: 1.1rem; font-weight: bold; color: var(--c-text); }
.emotion-card .ec-status { display: inline-flex; align-items: center; gap: .4rem; font-size: .78rem; }
.emotion-card .ec-status .dot { width: 8px; height: 8px; border-radius: 50%; display: inline-block; }
.emotion-card .ec-status.done .dot { background: #2E7D32; }
.emotion-card .ec-status.done { color: #2E7D32; }
.emotion-card .ec-status.wip .dot { background: var(--c-alert); }
.emotion-card .ec-status.wip { color: var(--c-alert); }
.emotion-card .ec-status.ongoing .dot { background: var(--c-blue); }
.emotion-card .ec-status.ongoing { color: var(--c-blue); }
.emotion-card .ec-scene { font-size: .875rem; color: var(--c-text-weak); margin-bottom: .75rem; line-height: 1.6; }
.emotion-card .ec-meta { display: flex; gap: 1rem; font-size: .8rem; color: var(--c-text-weak); }
.emotion-card .ec-meta span { display: inline-flex; align-items: center; gap: .3rem; }
@media (max-width: 1024px) { .emotion-card-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 640px)  { .emotion-card-grid { grid-template-columns: 1fr; } }

/* ---------- 25. 图标卡片（天翼痛点/价值主张，天盾输出物，统一同色系扁平图标） ---------- */
.icon-card-grid { display: grid; gap: 1.25rem; }
.icon-card {
  background: var(--c-bg); border: 1px solid var(--c-border); border-radius: 6px;
  padding: 1.75rem 1.5rem; transition: var(--tr);
}
.icon-card:hover { box-shadow: 0 8px 24px rgba(0,0,0,.08); transform: translateY(-3px); }
.icon-card .ic-icon {
  width: 44px; height: 44px; margin-bottom: 1rem; opacity: .85;
}
.icon-card .ic-icon img { width: 100%; height: 100%; object-fit: contain; }
/* 圆形浅底缩小图标变体：用于Lucide线条图标，避免铺满容器显得过大 */
.icon-card .ic-icon--circle {
  border-radius: 50%; background: rgba(229,72,77,.08);
  display: flex; align-items: center; justify-content: center; opacity: 1;
}
.icon-card .ic-icon--circle img { width: 55%; height: 55%; }
.icon-card .ic-title { font-size: 1rem; font-weight: bold; color: var(--c-text); margin-bottom: .5rem; }
.icon-card .ic-desc { font-size: .85rem; color: var(--c-text-weak); line-height: 1.7; }
/* 天翼页面局部覆盖：青蓝/钢蓝色系图标底色，与天枢主蓝区分 */
.tian-yi-page .icon-card:hover { border-color: #1F6F8B; }
.tian-yi-page .icon-card .ic-icon { filter: hue-rotate(150deg) saturate(1.1); }

/* ---------- 25b. 支持范围矩阵（天枢层级/域级覆盖，编号分组+圆形图标徽标，高级感排版） ---------- */
.coverage-matrix {
  margin-top: 2.5rem; padding-top: 2.5rem; border-top: 1px solid var(--c-border);
  display: flex; align-items: flex-start; gap: 3rem;
}
.coverage-group { flex: 1; }
.coverage-group-head { display: flex; align-items: baseline; gap: .75rem; margin-bottom: 1.5rem; }
.coverage-group-num {
  font-family: var(--font-en); font-size: .8rem; color: var(--c-blue); letter-spacing: 1px;
  border: 1px solid var(--c-blue); border-radius: 999px; padding: .15rem .65rem;
}
.coverage-group-title { font-size: 1.05rem; font-weight: bold; color: var(--c-text); }
.coverage-icons { display: flex; flex-wrap: wrap; gap: 1.75rem; }
.coverage-icon { display: flex; flex-direction: column; align-items: center; gap: .65rem; width: 76px; }
.coverage-icon img {
  width: 56px; height: 56px; object-fit: contain; padding: 12px; box-sizing: border-box;
  border-radius: 50%; background: var(--c-bg); border: 1px solid var(--c-border);
  transition: var(--tr);
}
.coverage-icon span { font-size: .8rem; color: var(--c-text-weak); white-space: nowrap; }
.coverage-icon:hover img { border-color: var(--c-blue); box-shadow: 0 6px 18px rgba(38,89,255,.15); transform: translateY(-2px); }
.coverage-divider { width: 1px; align-self: stretch; background: var(--c-border); }
@media (max-width: 768px) {
  .coverage-matrix { flex-direction: column; gap: 2rem; }
  .coverage-divider { display: none; }
}

/* ---------- 25c. 天境多形态终端小卡片（图+标题+说明，图片实拍设备照） ---------- */
.terminal-card { text-align: center; }
.terminal-card .terminal-img {
  height: 96px; display: flex; align-items: center; justify-content: center; margin-bottom: 1rem;
}
.terminal-card .terminal-img img { max-width: 100%; max-height: 100%; object-fit: contain; }
.terminal-card h3 { font-size: .95rem; margin-bottom: .5rem; }
.terminal-card p { font-size: .8rem; color: var(--c-text-weak); line-height: 1.6; }

/* ---------- 26. 天磁科学仪器感强化：铜金/石墨色数字强调、对比条组件（页面级覆盖，不进:root全局变量） ---------- */
.tian-ci-page { --c-ci-accent: #8a6d3b; --c-ci-graphite: #4a4a48; }
.tian-ci-page .kpi-item .num { color: var(--c-ci-graphite); }
.tian-ci-page .compare-bar-group { display: flex; flex-direction: column; gap: 1.1rem; }
.tian-ci-page .compare-bar-item .cb-label { display: flex; justify-content: space-between; font-size: .85rem; color: var(--c-text-weak); margin-bottom: .4rem; }
.tian-ci-page .compare-bar-item .cb-track { height: 8px; border-radius: 4px; background: var(--c-border); overflow: hidden; }
.tian-ci-page .compare-bar-item .cb-fill { height: 100%; border-radius: 4px; background: var(--c-ci-accent); }
.tian-ci-page .compare-bar-item .cb-fill--baseline { background: var(--c-text-weak); opacity: .5; }

/* ---------- 27. 天枢核心功能闭环：单图居中环形图，节点悬浮展开详情，替代此前左文右图布局 ---------- */
.core-loop {
  position: relative; width: min(640px, 100%); max-width: 640px; aspect-ratio: 1 / 1;
  margin: 2.5rem auto 0;
}
.core-loop-svg { position: absolute; inset: 0; width: 100%; height: 100%; overflow: visible; }
.loop-guide { fill: none; stroke: var(--c-border); stroke-width: 1; stroke-dasharray: 2 6; }
.loop-arc { fill: none; stroke: var(--c-blue); stroke-width: 2; opacity: .55; }
.loop-arc--alert { stroke: var(--c-alert); opacity: .65; }
.loop-arr-fill { fill: var(--c-blue); opacity: .55; }
.loop-arr-fill--alert { fill: var(--c-alert); opacity: .65; }

.loop-center {
  position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%);
  width: 27%; height: 27%; border-radius: 50%;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  background: linear-gradient(160deg, #fff, var(--c-bg-alt));
  border: 1px solid var(--c-border); box-shadow: 0 12px 32px rgba(38,89,255,.12), inset 0 0 0 1px rgba(255,255,255,.6);
}
.loop-center-label { font-size: 1.15rem; font-weight: bold; color: var(--c-blue); letter-spacing: 1px; }
.loop-center-sub { font-size: .72rem; color: var(--c-text-weak); margin-top: .3rem; }

.loop-node {
  position: absolute; transform: translate(-50%, -50%); z-index: 2;
  display: flex; flex-direction: column; align-items: center; width: 92px;
  cursor: default; transition: var(--tr);
}
.loop-node img {
  width: 64px; height: 64px; object-fit: contain; border-radius: 50%;
  background: #fff; box-shadow: 0 4px 14px rgba(20,30,60,.10);
  transition: var(--tr);
}
.loop-node-label {
  margin-top: .5rem; font-size: .82rem; font-weight: bold; color: var(--c-text);
  white-space: nowrap; display: flex; align-items: center; gap: .3rem;
}
.loop-node .ln-num {
  font-family: var(--font-en); font-size: .68rem; font-weight: bold; color: var(--c-blue); opacity: .7;
}
.loop-node.is-alert .loop-node-label { color: var(--c-alert); }
.loop-node.is-alert .ln-num { color: var(--c-alert); }
.loop-node.is-alert img { box-shadow: 0 4px 14px rgba(175,30,40,.16); }

.loop-node:hover, .loop-node:focus-visible { z-index: 5; outline: none; }
.loop-node:hover img, .loop-node:focus-visible img {
  transform: scale(1.12); box-shadow: 0 10px 26px rgba(38,89,255,.28);
}
.loop-node.is-alert:hover img, .loop-node.is-alert:focus-visible img {
  box-shadow: 0 10px 26px rgba(175,30,40,.3);
}

/* 悬浮详情：从节点上方浮出，居中对齐，高级感卡片而非原生title提示 */
.loop-tip {
  position: absolute; bottom: calc(100% + 14px); left: 50%; transform: translateX(-50%) translateY(6px);
  width: 220px; padding: .9rem 1.1rem; border-radius: 8px;
  background: #fff; border: 1px solid var(--c-border); box-shadow: 0 16px 40px rgba(20,30,60,.18);
  font-size: .82rem; line-height: 1.6; color: var(--c-text-weak); text-align: left;
  opacity: 0; visibility: hidden; pointer-events: none;
  transition: opacity .25s ease, transform .25s ease; z-index: 10;
}
.loop-tip::after {
  content: ""; position: absolute; top: 100%; left: 50%; transform: translateX(-50%);
  border: 6px solid transparent; border-top-color: #fff;
}
.loop-node:hover .loop-tip, .loop-node:focus-visible .loop-tip {
  opacity: 1; visibility: visible; transform: translateX(-50%) translateY(0);
}
/* 顶部三个节点（01/02/08）紧邻容器上边缘，详情卡改为向下弹出，避免顶出容器 */
.loop-node--tip-below .loop-tip {
  bottom: auto; top: calc(100% + 14px); transform: translateX(-50%) translateY(-6px);
}
.loop-node--tip-below .loop-tip::after {
  top: auto; bottom: 100%; border-top-color: transparent; border-bottom-color: #fff;
}
.loop-node--tip-below:hover .loop-tip, .loop-node--tip-below:focus-visible .loop-tip {
  transform: translateX(-50%) translateY(0);
}
/* 最右/最左节点（03导调/07自主博弈）详情卡靠边对齐，避免居中弹出时超出容器 */
.loop-node--tip-left .loop-tip { left: auto; right: 0; transform: translateY(6px); }
.loop-node--tip-left .loop-tip::after { left: auto; right: 20px; transform: none; }
.loop-node--tip-left:hover .loop-tip, .loop-node--tip-left:focus-visible .loop-tip { transform: translateY(0); }
.loop-node--tip-right .loop-tip { left: 0; right: auto; transform: translateY(6px); }
.loop-node--tip-right .loop-tip::after { left: 20px; transform: none; }
.loop-node--tip-right:hover .loop-tip, .loop-node--tip-right:focus-visible .loop-tip { transform: translateY(0); }

@media (max-width: 720px) {
  .core-loop { width: 100%; max-width: 420px; }
  .loop-node { width: 66px; }
  .loop-node img { width: 44px; height: 44px; }
  .loop-node-label { font-size: .7rem; }
  .loop-tip { width: 160px; font-size: .75rem; padding: .7rem .85rem; }
}

/* ---------- 28. 天盾流程带图标变体：.process-timeline上叠加图标插槽，用于"应用案例操作流程"五步 ---------- */
.process-timeline--icon .pt-step { display: flex; flex-direction: column; align-items: flex-start; }
.process-timeline--icon .pt-icon {
  width: 48px; height: 48px; object-fit: contain; margin-bottom: 1rem;
}

/* ---------- 30. 模块轮播（天翼核心功能模块/亮点功能：参考恒歌"模型装配"模块——顶部胶囊标签导航 + 左图右卡片网格，卡片图标装饰性裁切在右下角） ---------- */
.module-carousel-nav-wrap { display: flex; justify-content: center; margin-bottom: 2.5rem; }
.module-carousel-nav {
  display: inline-flex; flex-wrap: wrap; border-radius: 30px; background: #fff;
  box-shadow: 0 4px 12px rgba(61,61,61,.1); padding: .3rem;
}
.module-carousel-nav .mc-nav-item {
  height: 3.125rem; padding: 0 1.75rem; border-radius: 25px; display: flex; align-items: center; justify-content: center;
  font-size: 1rem; color: var(--c-text); transition: var(--tr); white-space: nowrap;
}
.module-carousel-nav .mc-nav-item.active { background: var(--c-blue); color: #fff; }
.module-carousel-panel { display: none; }
.module-carousel-panel.active { display: block; }
.module-carousel-panel .mc-box { display: flex; gap: 2rem; align-items: stretch; }
.module-carousel-panel .mc-panel-img {
  width: 42%; max-width: 600px; flex-shrink: 0; border-radius: .75rem; overflow: hidden;
  border: 1px solid var(--c-border); background: var(--c-bg-alt);
}
.module-carousel-panel .mc-panel-img img { width: 100%; height: 100%; object-fit: cover; display: block; }
.module-carousel-panel .mc-points {
  flex: 1; height: 100%; display: grid; grid-template-columns: repeat(2, 1fr); grid-auto-rows: 1fr; gap: 1.1rem;
}
.module-carousel-panel .mc-point {
  border-radius: 8px; background: var(--c-bg-alt2); border: 1px solid var(--c-border);
  padding: 1.75rem 1.5rem; display: flex; flex-direction: column; justify-content: center; transition: var(--tr);
}
.module-carousel-panel .mc-point:hover { border-color: var(--c-blue); background: #fff; box-shadow: 0 4px 14px rgba(0,0,0,.06); }
.module-carousel-panel .mc-point-title { font-size: 1.15rem; color: var(--c-text); font-weight: bold; margin-bottom: .65rem; }
.module-carousel-panel .mc-point-desc { font-size: .9rem; color: var(--c-text-weak); line-height: 1.7; }
@media (max-width: 900px) {
  .module-carousel-panel .mc-box { flex-direction: column; }
  .module-carousel-panel .mc-panel-img { width: 100%; max-width: none; height: auto; }
  .module-carousel-panel .mc-panel-img img { height: auto; object-fit: contain; }
  .module-carousel-panel .mc-points { height: auto; }
  .module-carousel-nav .mc-nav-item { padding: 0 1.1rem; font-size: .9rem; }
}
@media (max-width: 600px) {
  .module-carousel-panel .mc-points { grid-template-columns: 1fr; }
}
.process-timeline--icon .pt-num { margin-bottom: .35rem; }

/* ---------- 31. 产品矩阵四维流程（人/战/网/装大图卡片+箭头串联，替代小图标卡片，图片信息量大需要更大展示尺寸） ---------- */
.dim-flow { display: flex; align-items: center; gap: 0; }
.dim-flow-item { flex: 1; min-width: 0; }
.dim-flow-head {
  background: var(--c-text); color: #fff; font-size: .85rem; font-weight: bold;
  text-align: center; padding: .65rem .5rem; border-radius: 4px 4px 0 0;
}
.dim-flow-img {
  position: relative; aspect-ratio: 4 / 3; overflow: hidden; border-radius: 0 0 4px 4px;
  border: 1px solid var(--c-border); border-top: none; background: var(--c-bg-alt);
}
.dim-flow-img img { width: 100%; height: 100%; object-fit: cover; display: block; }
.dim-flow-char {
  position: absolute; left: .75rem; bottom: .5rem; font-family: var(--font-en);
  font-size: 2.75rem; font-weight: bold; color: #fff; line-height: 1;
  text-shadow: 0 2px 10px rgba(0,0,0,.55);
}
.dim-flow-caption { text-align: center; font-size: .85rem; color: var(--c-text-weak); margin-top: .75rem; }
.dim-flow-arrow {
  flex: 0 0 auto; width: 1.75rem; height: 2px; background: var(--c-border); position: relative; margin: 0 .5rem;
  align-self: center; margin-top: -1.6rem;
}
.dim-flow-arrow::after {
  content: ""; position: absolute; right: -1px; top: 50%; transform: translateY(-50%);
  width: 0; height: 0; border-top: 5px solid transparent; border-bottom: 5px solid transparent; border-left: 7px solid var(--c-border);
}
@media (max-width: 900px) {
  .dim-flow { flex-direction: column; align-items: stretch; }
  .dim-flow-arrow { display: none; }
  .dim-flow-item { margin-bottom: 1.5rem; }
}

/* ============================================================
   恒歌风格优化新增样式 - Phase 1
   ============================================================ */

/* ---------- 导航栏大型悬浮菜单 ---------- */
.nav_sub_pro {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(14, 15, 18, 0.8);
  backdrop-filter: blur(10px);
  opacity: 0;
  visibility: hidden;
  transform: translateX(-50%) translateY(-10px);
  transition: opacity 0.3s, visibility 0.3s, transform 0.3s;
  z-index: 100;
  min-width: auto;
  width: fit-content;
  border-radius: 0 0 8px 8px;
  overflow: visible;
}

/* 单列菜单宽度自适应 */
.nav_sub_pro--single {
  min-width: auto;
  max-width: 260px;
  width: auto;
}

.nav_sub_pro--single .box {
  gap: 0;
  padding: 0;
}

.nav > li:hover .nav_sub_pro {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

.nav_sub_pro .box {
  display: flex;
  gap: 0;
  width: fit-content;
  overflow: visible;
}

/* 分类标题行 */
.nav_sub_pro .box dt {
  height: 3.125rem;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #444A50;
  padding: 0 24px;
  font-size: 15px;
  color: #fff;
  font-weight: 500;
  width: 100%;
  white-space: nowrap;
  text-align: center;
}

.nav_sub_pro .box dt a {
  color: #fff;
  transition: 0.3s;
  display: block;
  width: 100%;
  text-align: center;
}

.nav_sub_pro .box dt a:hover {
  color: #53D7E5;
}

.nav_sub_pro .box dt .ico {
  width: 44px;
  margin-right: 10px;
  height: 23px;
  display: flex;
  align-items: center;
  justify-content: flex-end;
}

.nav_sub_pro .box dt .ico img {
  width: 18px;
  height: 18px;
  opacity: 0.8;
}

/* 单列菜单样式（纯列表，无标题栏） */
.nav_sub_pro .box dl.nav_single_column {
  width: 100%;
  padding: 0;
  overflow: visible;
}

.nav_sub_pro .box dl.nav_single_column dd {
  padding: 0;
}

.nav_sub_pro .box dl.nav_single_column dd:first-child {
  padding-top: 0;
}

.nav_sub_pro .box dl.nav_single_column dd a {
  display: flex;
  padding: 12px 24px;
  transition: 0.3s;
  border-radius: 0;
  align-items: center;
  white-space: nowrap;
}

.nav_sub_pro .box dl.nav_single_column dd a:hover {
  background: rgba(68, 74, 80, 0.5);
}

.nav_sub_pro .box dl.nav_single_column .ico {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
  margin-right: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.nav_sub_pro .box dl.nav_single_column .ico img {
  width: 100%;
  height: 100%;
  opacity: 0.85;
}

.nav_sub_pro .box dl.nav_single_column .txt span {
  font-size: 14px;
  color: #FFF;
  line-height: 1.4;
  display: block;
  margin-bottom: 2px;
  transition: 0.3s;
  font-weight: 500;
}

.nav_sub_pro .box dl.nav_single_column .txt p {
  color: #FFF;
  opacity: 0.4;
  font-size: 10px;
  line-height: 1.3;
}

.nav_sub_pro .box dl.nav_single_column dd a:hover .txt span {
  background: linear-gradient(100deg, #53D7E5 0, #2659FF 99%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
/* ============================================================
   恒歌风格优化新增样式 - Phase 1
   追加到 design-system.css 末尾
   ============================================================ */

/* ---------- 导航栏大型悬浮菜单样式补充 ---------- */

/* 菜单项容器 */
.nav_sub_pro .box dd {
  padding: 10px 18px;
}

.nav_sub_pro .box dd > a {
  display: flex;
  padding: 8px 10px;
  transition: 0.3s;
  border-radius: 6px;
  align-items: center;
  white-space: nowrap;
}

.nav_sub_pro .box dd > a:hover {
  background: rgba(68, 74, 80, 0.7);
}

/* 图标区 */
.nav_sub_pro .box dd .ico {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  margin-right: 12px;
  margin-top: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.nav_sub_pro .box dd .ico img {
  width: 100%;
  height: 100%;
  opacity: 0.9;
}

/* 文字区 */
.nav_sub_pro .box dd .txt {
  text-align: left;
  width: auto;
  max-width: 100%;
  flex: 1;
}

.nav_sub_pro .box dd .txt span {
  font-size: 15px;
  color: #FFF;
  line-height: 1.4;
  display: block;
  white-space: nowrap;
  margin-bottom: 2px;
  transition: 0.3s;
  font-weight: 500;
}

.nav_sub_pro .box dd .txt p {
  color: #FFF;
  opacity: 0.45;
  font-size: 11px;
  line-height: 1.3;
  white-space: nowrap;
}

/* 渐变文字hover效果 - 核心高级感 */
.nav_sub_pro .box dd > a:hover .txt span {
  background: linear-gradient(100deg, #53D7E5 0, #2659FF 99%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-fill-color: transparent;
}

/* 试用板块 */
.nav_sub_pro .box dl.nav_shiyongbox dt {
  border-left: 1px solid rgba(14, 15, 18, 0.8);
}

.nav_sub_pro .box dl.nav_shiyongbox dd {
  padding: 30px 40px;
  border-left: 1px solid rgba(68, 74, 80, 0.5);
}

.nav_shiyongbox .inner {
  width: 10rem;
}

.nav_shiyongbox .img {
  position: relative;
  overflow: hidden;
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.05);
}

.nav_shiyongbox .img:after {
  content: "";
  display: block;
  padding-top: 56.25%; /* 16:9 */
}

.nav_shiyongbox .img img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.nav_shiyongbox .txt p {
  font-size: 14px;
  color: #fff;
  opacity: 0.8;
  line-height: 1.5rem;
  margin-top: 1rem;
}

.btn_try {
  width: 10rem;
  height: 2.8125rem;
  margin-top: 1.75rem;
  border-radius: 0.75rem;
  background: rgba(68, 74, 80, 0.8);
  border: 1px solid rgba(68, 74, 80, 0.8);
  font-size: 0.875rem;
  color: #FFF;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: 0.3s;
  position: relative;
  z-index: 1;
}

.btn_try:before {
  content: "";
  display: block;
  width: 100%;
  height: 100%;
  position: absolute;
  left: 0;
  top: 0;
  z-index: -1;
  transition: 0.5s;
  opacity: 0;
  visibility: hidden;
  background: linear-gradient(106deg, rgba(83, 214, 229, 0.8) 0, rgba(38, 89, 255, 0.8) 99%);
  border-radius: 0.75rem;
}

.btn_try:hover {
  border: 1px solid rgba(38, 89, 255, 0.8);
  background: rgba(38, 89, 255, 0.16);
}

.btn_try:active:before {
  opacity: 1;
  visibility: visible;
}

/* 移动端隐藏大型菜单 */
@media (max-width: 1024px) {
  .nav_sub_pro {
    display: none;
  }
}

/* ---------- 产品体系二级级联菜单（悬浮在"天枢"等产品条目上，右侧展开主要功能/应用案例/技术架构） ---------- */
/* ---------- 多级级联悬浮子菜单（支持完整图标卡片样式，递归多层） ---------- */
.nav_sub_pro .box dd.has-children {
  position: relative;
}

/* 用伪元素填充父子元素间的间隙，避免鼠标移动时菜单消失 */
.nav_sub_pro .box dd.has-children::after,
.nav-sub-children dd.has-children::after {
  content: '';
  position: absolute;
  top: 0;
  left: 100%;
  width: 20px;
  height: 100%;
  background: transparent;
  z-index: 9;
}

.nav-sub-children {
  position: absolute;
  top: 0;
  left: 100%;
  width: auto;
  max-width: 260px;
  background: rgba(14, 15, 18, 0.92);
  backdrop-filter: blur(10px);
  border-radius: 8px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transform: translateX(-6px);
  transition: 0.25s;
  z-index: 10;
  padding: 8px;
  margin-left: 0;
}

.nav_sub_pro .box dd.has-children:hover > .nav-sub-children,
.nav_single_column dd.has-children:hover > .nav-sub-children {
  opacity: 1;
  visibility: visible;
  transform: translateX(0);
  pointer-events: auto;
}

.nav-sub-children-inner {
  display: flex;
  flex-direction: column;
  overflow: visible;
}

/* 级联子菜单里的dl/dd，复用外层nav_sub_pro dd的完整结构 */
.nav-sub-children dl {
  display: flex;
  flex-direction: column;
  gap: 0;
  overflow: visible;
}

.nav-sub-children dd {
  position: relative;
  margin: 0;
  overflow: visible;
}

.nav-sub-children dd > a {
  display: flex;
  align-items: center;
  padding: 12px 16px;
  border-radius: 6px;
  transition: 0.3s;
  text-decoration: none;
  color: #fff;
  gap: 10px;
}

.nav-sub-children dd > a:hover {
  background: rgba(68, 74, 80, 0.7);
}

.nav-sub-children dd .ico {
  width: 16px;
  height: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  color: #fff;
}

.nav-sub-children dd .ico img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  opacity: 0.85;
  filter: brightness(0) invert(1);
}

.nav-sub-children dd > a:hover .ico img {
  opacity: 1;
}

.nav-sub-children dd .txt {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.nav-sub-children dd .txt span {
  font-size: 14px;
  font-weight: 500;
  color: #fff;
  line-height: 1.2;
  white-space: nowrap;
}

.nav-sub-children dd .txt p {
  font-size: 12px;
  color: rgba(255, 255, 255, 0.6);
  line-height: 1.2;
  margin: 0;
}

.nav-sub-children dd > a:hover .txt span {
  color: #53D7E5;
}

/* 多级级联嵌套：第三层第四层...子菜单同样生效 */
.nav-sub-children dd.has-children:hover > .nav-sub-children {
  opacity: 1;
  visibility: visible;
  transform: translateX(0);
  pointer-events: auto;
}


/* ---------- 三层结构按钮（恒歌式交互） ---------- */
.btn-enhanced {
  position: relative;
  z-index: 1;
  height: 2.5rem;
  padding: 0 2rem;
  border-radius: 20px;
  font-size: 0.875rem;
  color: var(--c-text);
  background: transparent;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: color 0.5s;
  cursor: pointer;
}

/* 边框层 */
.btn-enhanced:before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -2;
  border-radius: 20px;
  border: 1px solid var(--c-text);
  background: rgba(255, 255, 255, 0.1);
  transition: 0.5s;
}

/* 渐变激活层 */
.btn-enhanced:after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  border-radius: 20px;
  background: var(--grad-brand);
  opacity: 0;
  visibility: hidden;
  transition: 0.5s;
}

.btn-enhanced:hover {
  color: #fff;
}

.btn-enhanced:hover:before {
  background: var(--c-blue);
  border-color: var(--c-blue);
}

.btn-enhanced:active:before {
  opacity: 0;
}

.btn-enhanced:active:after {
  opacity: 1;
  visibility: visible;
}

/* 白色主题变体 */
.btn-enhanced.white {
  color: #fff;
}

.btn-enhanced.white:before {
  border-color: #fff;
  background: rgba(255, 255, 255, 0.1);
}

.btn-enhanced.white:hover:before {
  border-color: var(--c-blue);
  background: rgba(38, 89, 255, 0.2);
}

/* ---------- 渐变文字填充工具类 ---------- */
.text-gradient {
  background: linear-gradient(121deg, #53D7E5 0, #2659FF 99%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-fill-color: transparent;
}

.text-gradient-reverse {
  background: linear-gradient(270deg, #53D7E5 0, #FFF 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-fill-color: transparent;
}

/* ---------- 关于我们页优化样式 ---------- */

/* Banner渐变标题 */
.page-banner h1.gradient-title {
  background: linear-gradient(270deg, #53D7E5 0, #FFF 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-fill-color: transparent;
}

/* 左侧渐变遮罩 */
.page-banner.gradient-mask:before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, rgba(0, 0, 0, 0.8) 0, rgba(0, 0, 0, 0) 80%);
  z-index: 1;
}

.page-banner.gradient-mask .m {
  position: relative;
  z-index: 2;
}

/* 数字统计升级 */
.kpi-strip-enhanced {
  display: flex;
  align-items: stretch;
  justify-content: space-around;
  gap: 2rem;
  padding: 3rem 0;
}

.kpi-item-enhanced {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 1rem;
  position: relative;
}

.kpi-item-enhanced .icon {
  width: 2.6875rem;
  height: 2.6875rem;
  flex-shrink: 0;
}

.kpi-item-enhanced .icon img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.kpi-item-enhanced .content {
  flex: 1;
}

.kpi-item-enhanced .number {
  font-size: 3.75rem;
  font-weight: bold;
  background: linear-gradient(121deg, #53D7E5 0, #2659FF 99%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-fill-color: transparent;
  line-height: 1.2;
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
}

.kpi-item-enhanced .number .unit {
  font-size: 1rem;
  font-weight: bold;
  color: var(--c-text);
}

.kpi-item-enhanced .label {
  font-size: 1rem;
  color: var(--c-text);
  margin-top: 0.5rem;
  font-weight: normal;
}

/* 分割线 */
.kpi-item-enhanced:not(:last-child):after {
  content: "";
  position: absolute;
  right: -1rem;
  top: 50%;
  transform: translateY(-50%);
  width: 1px;
  height: 60%;
  background: var(--c-text);
  opacity: 0.2;
}

@media (max-width: 768px) {
  .kpi-strip-enhanced {
    flex-direction: column;
    gap: 2rem;
  }

  .kpi-item-enhanced:not(:last-child):after {
    display: none;
  }

  .kpi-item-enhanced .number {
    font-size: 2.5rem;
  }
}

/* 团队卡片升级 */
.panel-enhanced {
  background: rgba(255, 255, 255, 0.5);
  border: none;
  border-radius: 12px;
  padding: 2rem;
  transition: 0.5s;
}

.panel-enhanced:hover {
  background: #fff;
  box-shadow: 0 4px 12px rgba(61, 61, 61, 0.1);
  transform: translateY(-4px);
}

/* 时间轴组件（可选） */
.timeline {
  position: relative;
  display: flex;
  justify-content: space-around;
  align-items: flex-start;
  padding: 3rem 0;
  gap: 2rem;
}

.timeline:before {
  content: "";
  position: absolute;
  top: 2rem;
  left: 10%;
  right: 10%;
  height: 2px;
  background: linear-gradient(90deg, #53D7E5 0, #2659FF 100%);
  z-index: 0;
}

.timeline-item {
  position: relative;
  z-index: 1;
  flex: 1;
  text-align: center;
}

.timeline-dot {
  width: 16px;
  height: 16px;
  border: 2px solid #FFF;
  box-shadow: 0 0 4px 0 #FFF;
  border-radius: 50%;
  position: relative;
  margin: 0 auto 1rem;
}

.timeline-dot:after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 6px;
  height: 6px;
  background: #26F8FF;
  border-radius: 50%;
}

.timeline-content {
  padding: 10px 20px;
  border-radius: 6px;
  transition: 0.5s;
}

.timeline-content:hover {
  background: linear-gradient(180deg, rgba(38, 248, 255, 0) 0, rgba(38, 248, 255, 0.35) 100%);
}

.timeline-content h4 {
  font-size: 1.5rem;
  font-weight: bold;
  color: #26F8FF;
  margin-bottom: 5px;
}

.timeline-content p {
  color: #fff;
  font-size: 0.875rem;
  opacity: 0.9;
}

@media (max-width: 900px) {
  .timeline {
    flex-direction: column;
    align-items: center;
  }

  .timeline:before {
    left: 50%;
    top: 0;
    bottom: 0;
    width: 2px;
    height: auto;
    transform: translateX(-50%);
  }

  .timeline-item {
    width: 100%;
    max-width: 400px;
  }
}

/* ============================================================
   首页恒歌风格优化 - 照搬恒歌 .s_pro / .s_shuzi 规范，仅替换内容
   规范来源：C:\Users\15932\Desktop\恒歌科技源码-视觉参考提取\恒歌科技-首页.html
   ============================================================ */

/* ---------- Hero区：下拉提示动画已有(.scroll-hint)，标题渐变关键词span ---------- */
.hero-title .hl {
  background: linear-gradient(108deg, #53D7E5 0%, #2659FF 99%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ---------- 产品大卡片（恒歌 .s_pingtailist 规范：图+图标+标题+英文+描述） ---------- */
.product-big-grid { gap: 1.25rem; }
.product-big-card {
  display: flex; flex-direction: column;
  background: rgba(255,255,255,.8);
  border-radius: 6px;
  overflow: hidden;
  transition: var(--tr);
}
.product-big-card:hover { box-shadow: 0 8px 24px rgba(0,0,0,.1); transform: translateY(-4px); }
.product-big-card .pb-img { height: 200px; overflow: hidden; background: var(--c-bg-alt); }
.product-big-card .pb-img img { width: 100%; height: 100%; object-fit: cover; transition: var(--tr-slow); }
.product-big-card:hover .pb-img img { transform: scale(1.06); }
.product-big-card .pb-body { padding: 1.875rem; flex: 1; display: flex; flex-direction: column; }
.product-big-card .pb-icon { width: 50px; height: 44px; margin-bottom: .625rem; }
.product-big-card .pb-icon img { width: 100%; height: 100%; object-fit: contain; }
.product-big-card h3 { font-size: 1.5rem; margin-bottom: .25rem; color: var(--c-text); }
.product-big-card h4 {
  font-family: var(--font-en); font-size: .875rem; font-weight: normal;
  color: var(--c-text-weak); margin-bottom: .875rem; letter-spacing: .5px;
}
.product-big-card p {
  font-size: .875rem; line-height: 1.6; color: var(--c-text-weak); flex: 1;
  display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden;
}
@media (max-width: 1024px) { .product-big-grid.grid-3 { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 640px)  { .product-big-grid.grid-3 { grid-template-columns: 1fr; } }

/* ---------- 关于我们数字展示（恒歌 .s_shuzi 规范：渐变大字号+单位+说明） ---------- */
.about-shuzi { display: flex; gap: 3.125rem; margin-top: 2.5rem; flex-wrap: wrap; }
.about-shuzi .item { display: flex; flex-direction: column; }
.about-shuzi .num-row { display: flex; align-items: baseline; gap: .25rem; }
.about-shuzi .num-row .num {
  font-size: 1.875rem; line-height: 2.75rem; font-weight: bold;
  background: var(--grad-brand); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}
.about-shuzi .num-row .unit { font-size: .875rem; font-weight: bold; color: var(--c-blue); padding-bottom: .5rem; }
.about-shuzi .desc { font-size: .875rem; color: var(--c-text-weak); margin-top: .25rem; }
@media (max-width: 640px) { .about-shuzi { gap: 1.5rem; } }

/* ============================================================
   适用客户卡片（照搬恒歌 GIS可视化页 .n_pro_ys 规范，仅替换内容和图标）
   规范来源：C:\Users\15932\Desktop\恒歌科技源码-视觉参考提取\
             恒歌科技-GIS可视化.html + style.css(.n_pro_ys) + base.css(.ico_tgl)
   默认态：白底、蓝色图标底座、深灰文字
   Hover态：蓝青渐变底、白色图标底座、白色文字（用 currentColor 简化恒歌原方案的双图切换）
   ============================================================ */
/* grid替代恒歌原版flex：卡片数量不整除时(如6个)不会出现flex-grow拉伸最后一行的问题 */
.customer-card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 1.25rem; }
.customer-card-grid .cc-item { padding: 0; }
.customer-card-grid .cc-box {
  text-align: center; background: #FFF;
  padding: 1.625rem 1.25rem; height: 100%;
  position: relative; z-index: 1; overflow: hidden;
}
.customer-card-grid .cc-box:before {
  content: ""; display: block; width: 100%; height: 100%;
  position: absolute; left: 0; top: 0;
  background: var(--grad-brand);
  z-index: -1; transition: var(--tr); opacity: 0; visibility: hidden;
}
.customer-card-grid .cc-box:hover:before { opacity: 1; visibility: visible; }

.customer-card-grid .cc-ico {
  width: 2.5rem; height: 2.5rem; margin: 0 auto 1.25rem;
  box-shadow: 5px 10px 10px 0 rgba(38,89,255,.3);
  background: var(--c-blue); border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  transition: var(--tr);
  color: #fff; /* 图标用 currentColor，跟随此处颜色 */
}
.customer-card-grid .cc-ico svg { width: 1.25rem; height: 1.25rem; display: block; }
.customer-card-grid .cc-box:hover .cc-ico {
  background: #FFF;
  box-shadow: 5px 10px 10px 0 rgba(255,255,255,.3);
  color: var(--c-blue);
}

.customer-card-grid .cc-title {
  font-size: 1.125rem; font-weight: bold; margin-bottom: .625rem;
  transition: var(--tr); color: var(--c-text); line-height: 1.625rem;
}
.customer-card-grid .cc-desc {
  color: var(--c-text); line-height: 1.5rem; font-size: .875rem;
  transition: var(--tr); opacity: .5;
}
.customer-card-grid .cc-box:hover .cc-title { color: #fff; }

/* ---------- 31. 图文堆叠模块（迪捷软件风格：左图右文字，多组纵向堆叠，静态无需JS，参考自 module-carousel 的 mc-box 视觉语言） ---------- */
.feature-row-group { display: flex; flex-direction: column; gap: 3.5rem; }
.feature-row { display: flex; gap: 3rem; align-items: center; }
.feature-row:nth-child(even) { flex-direction: row-reverse; }
.feature-row .fr-img {
  width: 50%; flex-shrink: 0; border-radius: .75rem; overflow: hidden;
  border: 1px solid var(--c-border); background: var(--c-bg-alt);
}
.feature-row .fr-img img { width: 100%; height: 100%; object-fit: cover; display: block; }
.feature-row .fr-text { flex: 1; }
.feature-row .fr-text .fr-num {
  font-family: var(--font-en); font-size: 1.5rem; font-weight: bold; color: var(--c-blue); opacity: .35; line-height: 1; margin-bottom: .75rem; display: block;
}
.feature-row .fr-text h3 { font-size: 1.375rem; color: var(--c-text); font-weight: bold; margin-bottom: 1rem; }
.feature-row .fr-text .fr-points { display: flex; flex-direction: column; gap: 1rem; }
.feature-row .fr-text .fr-point { padding-left: 1.1rem; border-left: 2px solid var(--c-border); }
.feature-row .fr-text .fr-point-title { font-size: 1rem; color: var(--c-text); font-weight: bold; margin-bottom: .35rem; }
.feature-row .fr-text .fr-point-desc { font-size: .875rem; color: var(--c-text-weak); line-height: 1.7; }
@media (max-width: 900px) {
  .feature-row, .feature-row:nth-child(even) { flex-direction: column; }
  .feature-row .fr-img { width: 100%; }
}
.customer-card-grid .cc-box:hover .cc-desc { color: #fff; opacity: 1; }

/* auto-fit已自动响应式换行，无需额外media query覆盖width */

/* ---------- 32. 回到顶部按钮（全站通用，JS动态注入） ---------- */
.back-to-top {
  position: fixed; right: 1.75rem; bottom: 1.75rem; z-index: 999;
  width: 48px; height: 48px; border-radius: 50%; border: none; cursor: pointer;
  background: var(--grad-brand); color: #fff;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 6px 18px rgba(38, 89, 255, .3);
  opacity: 0; visibility: hidden; transform: translateY(12px);
  transition: opacity var(--tr), visibility var(--tr), transform var(--tr), box-shadow var(--tr);
}
.back-to-top.is-visible { opacity: 1; visibility: visible; transform: translateY(0); }
.back-to-top:hover { box-shadow: 0 8px 22px rgba(38, 89, 255, .45); transform: translateY(-2px); }
.back-to-top svg { width: 22px; height: 22px; }
@media (max-width: 640px) {
  .back-to-top { right: 1.25rem; bottom: 1.25rem; width: 44px; height: 44px; }
}