/* ==========================================================================
   《寻秦》官网 · 东方仙侠设计系统（多主题）
   四套配色取自主视觉 bg_01.jpg（青绿山水 + 橙红灯笼）：
     shanshui 青绿山水（默认）· day 晴空白昼 · lantern 灯笼朱夜 · ink 墨青水墨
   字体：马善政毛笔楷书（标题）+ 霞鹜文楷屏显版（正文），自托管于 fonts/
   ========================================================================== */
@import url("../fonts/mashanzheng/mashanzheng.css");
@import url("../fonts/wenkai/lxgwwenkaiscreen.css");

/* ---------- 主题：青绿山水（默认） ---------- */
:root {
  color-scheme: dark;
  --bg-0: #071418;            /* 页面底色 */
  --bg-1: #0a1d23;            /* 区块底 */
  --bg-2: #0e252d;            /* 卡片底 */
  --card-hi: #12333d;         /* 卡片渐变亮端 */
  --card-lo: #0a2129;         /* 卡片渐变暗端 */
  --raise: rgba(14, 37, 45, .6);   /* 浮起小底（药丸/分页/条目底） */
  --accent: #4fa8b2;          /* 主色 · 青碧 */
  --accent-strong: #8fd4dc;   /* 强调 · 标题/hover/高对比 */
  --accent-deep: #2f7d88;     /* 主色深端 */
  --accent-rgb: 79, 168, 178;
  --on-accent: #06272d;       /* 主色按钮上的文字 */
  --btn-grad: linear-gradient(180deg, #8fd4dc, #4fa8b2 58%, #2f7d88);
  --flame: #ff6b35;           /* 暖强调 · 灯笼橙 */
  --flame-strong: #ff8a5c;
  --flame-deep: #d8551f;
  --flame-rgb: 255, 107, 53;
  --on-flame: #fff4ec;
  --flame-grad: linear-gradient(180deg, #ff8a5c, #ff6b35 55%, #d8551f);
  --jade: #37858f;            /* 辅助青 */
  --jade-rgb: 55, 133, 143;
  --text: #e9f4f4;
  --text-dim: #a9c2c6;
  --text-faint: #7c979c;
  --line: rgba(var(--accent-rgb), .3);
  --line-soft: rgba(var(--accent-rgb), .15);
  --veil-rgb: 5, 14, 18;      /* 遮罩基色（图上压字/半透明底） */
  --nav-rgb: 7, 20, 25;       /* 导航底色 */
  --font-title: "Ma Shan Zheng", "LXGW WenKai Screen", "STKaiti", "KaiTi", "Noto Serif SC", serif;
  --font-body: "LXGW WenKai Screen", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --wrap: 1200px;
  --radius: 10px;
  --shadow: 0 10px 30px rgba(0, 0, 0, .5);
  --ease: cubic-bezier(.22, .61, .36, 1);
  --card-grad: linear-gradient(165deg, var(--card-hi), var(--card-lo));
}

/* ---------- 主题：晴空白昼（浅色） ---------- */
:root[data-theme="day"] {
  color-scheme: light;
  --bg-0: #edf5f8;
  --bg-1: #e2eef3;
  --bg-2: #fbfdfe;
  --card-hi: #ffffff;
  --card-lo: #f0f7f9;
  --raise: rgba(255, 255, 255, .72);
  --accent: #2a7a85;
  --accent-strong: #175862;
  --accent-deep: #4d97a2;
  --accent-rgb: 42, 122, 133;
  --on-accent: #ffffff;
  --btn-grad: linear-gradient(180deg, #3e8b96, #2a7a85 58%, #1e626d);
  --flame: #e8551f;
  --flame-strong: #f06a38;
  --flame-deep: #c24312;
  --flame-rgb: 232, 85, 31;
  --on-flame: #ffffff;
  --flame-grad: linear-gradient(180deg, #f06a38, #e8551f 55%, #c24312);
  --jade: #33707c;
  --jade-rgb: 51, 112, 124;
  --text: #17333c;
  --text-dim: #4c6670;
  --text-faint: #6e8791;
  --line: rgba(42, 122, 133, .38);
  --line-soft: rgba(42, 122, 133, .18);
  --veil-rgb: 244, 251, 253;
  --nav-rgb: 255, 255, 255;
  --shadow: 0 10px 30px rgba(23, 63, 74, .16);
}

/* ---------- 主题：灯笼朱夜（暖色反转） ---------- */
:root[data-theme="lantern"] {
  color-scheme: dark;
  --bg-0: #0c121d;
  --bg-1: #101827;
  --bg-2: #16202f;
  --card-hi: #1b2637;
  --card-lo: #121a29;
  --raise: rgba(22, 32, 47, .6);
  --accent: #ff8a4d;
  --accent-strong: #ffb98a;
  --accent-deep: #c2531f;
  --accent-rgb: 255, 138, 77;
  --on-accent: #3a1403;
  --btn-grad: linear-gradient(180deg, #ffb98a, #ff8a4d 58%, #d8622a);
  --flame: #4a9fa8;
  --flame-strong: #7cc7cf;
  --flame-deep: #2f6d78;
  --flame-rgb: 74, 159, 168;
  --on-flame: #052a2e;
  --flame-grad: linear-gradient(180deg, #7cc7cf, #4a9fa8 55%, #2f6d78);
  --jade: #4a9fa8;
  --jade-rgb: 74, 159, 168;
  --text: #f7ede2;
  --text-dim: #c7b199;
  --text-faint: #96816a;
  --line: rgba(255, 138, 77, .3);
  --line-soft: rgba(255, 138, 77, .15);
  --veil-rgb: 12, 18, 29;
  --nav-rgb: 16, 24, 39;
  --shadow: 0 10px 30px rgba(0, 0, 0, .5);
}

/* ---------- 主题：墨青水墨（素雅收敛） ---------- */
:root[data-theme="ink"] {
  color-scheme: dark;
  --bg-0: #101418;
  --bg-1: #151b21;
  --bg-2: #1b242c;
  --card-hi: #212c35;
  --card-lo: #171f27;
  --raise: rgba(27, 36, 44, .6);
  --accent: #7d99a3;
  --accent-strong: #adc6ce;
  --accent-deep: #55707a;
  --accent-rgb: 125, 153, 163;
  --on-accent: #101a1f;
  --btn-grad: linear-gradient(180deg, #adc6ce, #7d99a3 58%, #5d7781);
  --flame: #c0392b;
  --flame-strong: #d4553f;
  --flame-deep: #992c21;
  --flame-rgb: 192, 57, 43;
  --on-flame: #f7e9d6;
  --flame-grad: linear-gradient(180deg, #d4553f, #c0392b 55%, #992c21);
  --jade: #6a8892;
  --jade-rgb: 106, 136, 146;
  --text: #ece7db;
  --text-dim: #b0a996;
  --text-faint: #847e6c;
  --line: rgba(125, 153, 163, .28);
  --line-soft: rgba(125, 153, 163, .14);
  --veil-rgb: 16, 20, 24;
  --nav-rgb: 21, 27, 33;
  --shadow: 0 10px 30px rgba(0, 0, 0, .5);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font-body);
  background: var(--bg-0);
  color: var(--text);
  font-size: 17px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  transition: background .35s var(--ease), color .35s var(--ease);
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul, ol { list-style: none; }
button { font-family: inherit; cursor: pointer; }

::selection { background: rgba(var(--accent-rgb), .35); color: #fff; }
:root[data-theme="day"] ::selection { color: #17333c; }
:focus-visible { outline: 2px solid var(--accent-strong); outline-offset: 3px; border-radius: 4px; }

.wrap { width: min(var(--wrap), 92%); margin: 0 auto; }

/* ==========================================================================
   顶部导航
   ========================================================================== */
.site-nav {
  position: fixed; inset: 0 0 auto 0; z-index: 100;
  transition: background .3s var(--ease), box-shadow .3s var(--ease);
  background: linear-gradient(to bottom, rgba(var(--veil-rgb), .82), rgba(var(--veil-rgb), .35));
  backdrop-filter: blur(8px);
}
.site-nav.is-solid {
  background: rgba(var(--nav-rgb), .96);
  box-shadow: 0 1px 0 var(--line-soft), 0 8px 24px rgba(0, 0, 0, .4);
}
:root[data-theme="day"] .site-nav.is-solid { box-shadow: 0 1px 0 var(--line-soft), 0 8px 24px rgba(23, 63, 74, .14); }
.nav-inner {
  width: min(1360px, 94%); margin: 0 auto;
  display: flex; align-items: center; gap: 28px;
  height: 72px;
}
.brand {
  display: flex; align-items: flex-start; gap: 12px; flex-shrink: 0;
  align-self: flex-start; height: 72px;
}
.brand img {
  height: 96px; width: auto; margin-top: 5px;
  filter: drop-shadow(0 4px 14px rgba(0, 0, 0, .55));
}
:root[data-theme="day"] .brand img { filter: drop-shadow(0 4px 14px rgba(23, 63, 74, .3)); }
.nav-links { display: flex; gap: 6px; margin-left: auto; }
.nav-links a {
  position: relative; padding: 8px 18px; font-size: 17px; letter-spacing: 2px;
  color: var(--text-dim); transition: color .25s;
}
.nav-links a::after {
  content: ""; position: absolute; left: 50%; bottom: 0; width: 0; height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
  transform: translateX(-50%); transition: width .3s var(--ease);
}
.nav-links a:hover { color: var(--accent-strong); }
.nav-links a:hover::after { width: 70%; }
.nav-links a.is-active { color: var(--accent-strong); }
.nav-links a.is-active::after { width: 70%; }
.nav-cta {
  flex-shrink: 0; display: inline-flex; align-items: center; gap: 8px;
  padding: 9px 22px; font-size: 15px; letter-spacing: 2px;
  color: var(--on-accent); border-radius: 999px; font-weight: 700;
  background: var(--btn-grad);
  box-shadow: 0 0 0 1px color-mix(in srgb, var(--accent-strong) 50%, transparent) inset, 0 4px 14px rgba(0, 0, 0, .35);
  transition: transform .25s var(--ease), box-shadow .25s;
}
.nav-cta:hover { transform: translateY(-2px); box-shadow: 0 0 0 1px color-mix(in srgb, var(--accent-strong) 60%, transparent) inset, 0 8px 20px rgba(var(--accent-rgb), .25); }
.nav-toggle {
  display: none; margin-left: auto; width: 44px; height: 44px;
  background: none; border: 1px solid var(--line); border-radius: 8px;
  color: var(--accent-strong); align-items: center; justify-content: center;
}

/* ==========================================================================
   主题切换器（由 ../js/theme.js 注入导航）
   ========================================================================== */
.theme-wrap { position: relative; flex-shrink: 0; }
.theme-btn {
  display: inline-flex; align-items: center; gap: 8px; height: 40px; padding: 0 14px;
  border-radius: 999px; background: rgba(var(--veil-rgb), .35);
  border: 1px solid var(--line); color: var(--accent-strong);
  font-size: 13.5px; letter-spacing: 2px;
  transition: border-color .25s, background .25s;
}
.theme-btn:hover { border-color: var(--accent); background: rgba(var(--accent-rgb), .1); }
.theme-btn .swatch {
  width: 14px; height: 14px; border-radius: 50%; background: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 28%, transparent);
}
.theme-menu {
  position: absolute; top: calc(100% + 10px); right: 0; min-width: 156px; padding: 8px;
  background: rgba(var(--nav-rgb), .97); border: 1px solid var(--line); border-radius: 10px;
  box-shadow: var(--shadow); backdrop-filter: blur(10px);
  opacity: 0; visibility: hidden; transform: translateY(-6px);
  transition: opacity .25s var(--ease), transform .25s var(--ease), visibility .25s;
  z-index: 120;
}
.theme-wrap.is-open .theme-menu { opacity: 1; visibility: visible; transform: none; }
.theme-menu button {
  display: flex; align-items: center; gap: 10px; width: 100%; padding: 9px 12px;
  border: none; background: none; border-radius: 7px;
  color: var(--text-dim); font-size: 14px; letter-spacing: 2px; text-align: left;
}
.theme-menu button:hover { background: rgba(var(--accent-rgb), .1); color: var(--accent-strong); }
.theme-menu button.is-on { color: var(--accent-strong); background: rgba(var(--accent-rgb), .14); font-weight: 700; }
.theme-menu .dot { width: 13px; height: 13px; border-radius: 4px; flex-shrink: 0; box-shadow: 0 0 0 1px rgba(0, 0, 0, .15) inset; }

/* ==========================================================================
   通用按钮
   ========================================================================== */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 10px;
  padding: 14px 40px; font-size: 18px; letter-spacing: 3px; border-radius: 6px;
  border: none; position: relative; transition: all .25s var(--ease); font-weight: 700;
}
.btn svg { width: 18px; height: 18px; }
.btn-gold {
  color: var(--on-accent);
  background: var(--btn-grad);
  box-shadow: 0 0 0 1px color-mix(in srgb, var(--accent-strong) 55%, transparent) inset, 0 6px 18px rgba(0, 0, 0, .35), 0 0 24px rgba(var(--accent-rgb), .12);
}
.btn-gold:hover { transform: translateY(-3px); box-shadow: 0 0 0 1px color-mix(in srgb, var(--accent-strong) 70%, transparent) inset, 0 10px 26px rgba(0, 0, 0, .4), 0 0 34px rgba(var(--accent-rgb), .28); }
.btn-ghost {
  color: var(--accent-strong); background: rgba(var(--veil-rgb), .4);
  border: 1px solid var(--accent); box-shadow: 0 0 0 3px rgba(var(--accent-rgb), .08) inset;
}
.btn-ghost:hover { background: rgba(var(--accent-rgb), .12); transform: translateY(-3px); }
.btn-red {
  color: var(--on-flame); background: var(--flame-grad);
  box-shadow: 0 4px 14px rgba(var(--flame-rgb), .35), 0 0 0 1px color-mix(in srgb, var(--flame-strong) 45%, transparent) inset;
}
.btn-red:hover { transform: translateY(-2px); box-shadow: 0 8px 20px rgba(var(--flame-rgb), .45); }
.btn-sm { padding: 9px 26px; font-size: 15px; letter-spacing: 2px; }

/* ==========================================================================
   卡片（角花边框：多重背景画四角 L 线）
   ========================================================================== */
.g-card {
  position: relative;
  background: var(--card-grad);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  transition: transform .3s var(--ease), border-color .3s, box-shadow .3s;
}
.g-card--corners {
  --cl: rgba(var(--accent-rgb), .75); --cs: 22px;
  background-image:
    linear-gradient(var(--cl), var(--cl)), linear-gradient(var(--cl), var(--cl)),
    linear-gradient(var(--cl), var(--cl)), linear-gradient(var(--cl), var(--cl)),
    linear-gradient(var(--cl), var(--cl)), linear-gradient(var(--cl), var(--cl)),
    linear-gradient(var(--cl), var(--cl)), linear-gradient(var(--cl), var(--cl)),
    var(--card-grad);
  background-position: 12px 12px, 12px 12px, calc(100% - 12px) 12px, calc(100% - 12px) 12px,
    12px calc(100% - 12px), 12px calc(100% - 12px), calc(100% - 12px) calc(100% - 12px), calc(100% - 12px) calc(100% - 12px), 0 0;
  background-size: var(--cs) 2px, 2px var(--cs), var(--cs) 2px, 2px var(--cs),
    var(--cs) 2px, 2px var(--cs), var(--cs) 2px, 2px var(--cs), 100% 100%;
  background-repeat: no-repeat;
}

/* ==========================================================================
   区块标题（中文大字 + 英文小字 + 云纹分隔线）
   ========================================================================== */
.sec { padding: 88px 0; position: relative; }
.sec-head { text-align: center; margin-bottom: 52px; }
.sec-head .sec-tag {
  display: inline-block; font-size: 13px; letter-spacing: 6px; color: var(--text-faint);
  text-transform: uppercase; margin-bottom: 10px;
}
.sec-head h2 {
  font-family: var(--font-title); font-size: clamp(30px, 4vw, 46px);
  letter-spacing: 10px; color: var(--accent-strong); font-weight: 600;
  text-shadow: 0 2px 18px rgba(var(--accent-rgb), .25);
}
.sec-head .sec-line {
  position: relative; height: 1px; width: min(420px, 70%); margin: 22px auto 0;
  background: linear-gradient(90deg, transparent, var(--accent) 30%, var(--accent) 70%, transparent);
}
.sec-head .sec-line::before {
  content: ""; position: absolute; left: 50%; top: 50%; width: 9px; height: 9px;
  background: var(--accent); transform: translate(-50%, -50%) rotate(45deg);
  box-shadow: 0 0 12px rgba(var(--accent-rgb), .8);
}
.sec-head .sec-line::after {
  content: ""; position: absolute; left: 50%; top: 50%; width: 26px; height: 26px;
  border: 1px solid var(--line); transform: translate(-50%, -50%) rotate(45deg);
}
.sec-head p.sec-desc { margin-top: 18px; color: var(--text-dim); font-size: 16.5px; letter-spacing: 1px; }

/* 印章（暖强调色） */
.seal-stamp {
  display: inline-flex; align-items: center; justify-content: center;
  width: 44px; height: 44px; background: var(--flame); color: var(--on-flame);
  font-family: var(--font-title); font-size: 15px; line-height: 1.1;
  border-radius: 5px; box-shadow: 0 2px 10px rgba(var(--flame-rgb), .4);
  writing-mode: vertical-rl; letter-spacing: 2px; padding: 4px;
}

/* 标签 */
.tag {
  display: inline-block; padding: 2px 12px; font-size: 13px; letter-spacing: 1px;
  border-radius: 3px; border: 1px solid; line-height: 1.8; white-space: nowrap;
}
.tag-notice { color: var(--accent-strong); border-color: rgba(var(--accent-rgb), .5); background: rgba(var(--accent-rgb), .08); }
.tag-version { color: color-mix(in srgb, var(--jade) 45%, var(--text)); border-color: rgba(var(--jade-rgb), .6); background: rgba(var(--jade-rgb), .12); }
.tag-event { color: color-mix(in srgb, var(--flame) 55%, var(--text)); border-color: rgba(var(--flame-rgb), .55); background: rgba(var(--flame-rgb), .1); }
.tag-guide { color: color-mix(in srgb, #9578c8 55%, var(--text)); border-color: rgba(149, 120, 200, .45); background: rgba(149, 120, 200, .08); }

/* ==========================================================================
   子页面 banner
   ========================================================================== */
.page-banner {
  position: relative; height: 420px; display: flex; align-items: center; justify-content: center;
  background-size: cover; background-position: center; padding-top: 72px;
}
.page-banner::before {
  content: ""; position: absolute; inset: 0;
  background: linear-gradient(to bottom, rgba(var(--veil-rgb), .55), rgba(var(--veil-rgb), .35) 40%, var(--bg-0));
}
.page-banner::after {  /* 底部主色边线 */
  content: ""; position: absolute; left: 0; right: 0; bottom: 0; height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
}
.page-banner .banner-title { position: relative; text-align: center; z-index: 1; }
.page-banner .banner-title h1 {
  font-family: var(--font-title); font-size: clamp(34px, 5vw, 56px);
  letter-spacing: 14px; color: var(--accent-strong); font-weight: 900;
  -webkit-text-stroke: 1px var(--accent-strong);
  text-shadow: 0 4px 24px rgba(var(--veil-rgb), .6);
}
.page-banner .banner-title .en {
  margin-top: 10px; font-size: 14px; letter-spacing: 8px; color: var(--text-dim); text-transform: uppercase;
}
.crumb {
  position: relative; z-index: 1; margin-top: 18px; font-size: 13px; color: var(--text-faint); letter-spacing: 2px;
}
.crumb a:hover { color: var(--accent-strong); }

/* ==========================================================================
   页脚
   ========================================================================== */
.site-footer {
  position: relative; margin-top: 60px;
  background: linear-gradient(to bottom, var(--bg-1), var(--bg-0));
  border-top: 1px solid var(--line-soft);
}
.site-footer::before {
  content: ""; position: absolute; top: -1px; left: 50%; transform: translateX(-50%);
  width: 60%; height: 1px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
}
.footer-grid {
  display: grid; grid-template-columns: 1.5fr 1fr 1fr 1.2fr; gap: 40px;
  padding: 56px 0 40px;
}
.footer-brand img { height: 72px; margin-bottom: 16px; }
.footer-brand p { color: var(--text-faint); font-size: 15px; max-width: 300px; }
.footer-col h4 {
  font-family: var(--font-title); font-size: 18px; color: var(--accent);
  letter-spacing: 4px; margin-bottom: 18px; font-weight: 600;
}
.footer-col li { margin-bottom: 10px; }
.footer-col a, .footer-col span { color: var(--text-faint); font-size: 15px; transition: color .2s; }
.footer-col a:hover { color: var(--accent-strong); }
.footer-hotline { font-size: 22px !important; color: var(--accent-strong) !important; font-family: var(--font-title); letter-spacing: 1px; }
.footer-social { display: flex; gap: 12px; margin-top: 14px; }
.footer-social a {
  width: 40px; height: 40px; border: 1px solid var(--line); border-radius: 50%;
  display: flex; align-items: center; justify-content: center; color: var(--text-dim);
  transition: all .25s;
}
.footer-social a:hover { color: var(--on-accent); background: var(--accent); border-color: var(--accent); transform: translateY(-3px); }
.footer-social svg { width: 18px; height: 18px; }
.footer-qr { position: relative; display: inline-flex; width: 40px; height: 40px; border: 1px solid var(--line); border-radius: 50%; align-items: center; justify-content: center; cursor: pointer; transition: all .25s; }
.footer-qr:hover, .footer-qr:focus { transform: translateY(-3px); border-color: var(--accent); }
.footer-qr-thumb { width: 30px; height: 30px; border-radius: 50%; object-fit: cover; }
.footer-qr-pop {
  position: absolute; bottom: calc(100% + 12px); left: 50%; transform: translateX(-50%) translateY(6px);
  display: flex; flex-direction: column; align-items: center; gap: 6px;
  padding: 10px; background: #fff; border-radius: 10px; z-index: 30;
  box-shadow: 0 12px 34px rgba(0,0,0,.28);
  opacity: 0; visibility: hidden; pointer-events: none; transition: opacity .2s, transform .2s, visibility .2s;
}
.footer-qr-pop::after { content: ""; position: absolute; top: 100%; left: 50%; transform: translateX(-50%); border: 7px solid transparent; border-top-color: #fff; }
.footer-qr-pop img { width: auto; height: auto; max-width: 86vw; max-height: 80vh; border-radius: 6px; }
.footer-qr-pop em { color: #333; font-size: 12px; font-style: normal; white-space: nowrap; }
.footer-qr:hover .footer-qr-pop, .footer-qr:focus .footer-qr-pop { opacity: 1; visibility: visible; transform: translateX(-50%) translateY(0); }
.footer-legal {
  border-top: 1px solid rgba(var(--accent-rgb), .1); padding: 20px 0 26px;
  text-align: center; color: color-mix(in srgb, var(--text-faint) 65%, var(--bg-0)); font-size: 13.5px; line-height: 2;
}
.footer-legal .health { color: var(--text-faint); }

/* ==========================================================================
   滚动动画
   ========================================================================== */
.reveal { opacity: 0; transform: translateY(34px); transition: opacity .7s var(--ease), transform .7s var(--ease); }
.reveal.is-in { opacity: 1; transform: none; }
.reveal-d1 { transition-delay: .1s; } .reveal-d2 { transition-delay: .2s; }
.reveal-d3 { transition-delay: .3s; } .reveal-d4 { transition-delay: .4s; }

/* 回顶 */
.back-top {
  position: fixed; right: 26px; bottom: 30px; z-index: 90;
  width: 46px; height: 46px; border-radius: 8px;
  background: rgba(var(--nav-rgb), .9); border: 1px solid var(--line);
  color: var(--accent-strong); display: flex; align-items: center; justify-content: center;
  opacity: 0; visibility: hidden; transform: translateY(10px);
  transition: all .3s var(--ease);
}
.back-top.is-show { opacity: 1; visibility: visible; transform: none; }
.back-top:hover { background: var(--accent); color: var(--on-accent); }
.back-top svg { width: 20px; height: 20px; }

/* ==========================================================================
   响应式
   ========================================================================== */
@media (max-width: 1080px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 860px) {
  .brand { height: 64px; }
  .brand img { height: 78px; margin-top: 4px; }
  .nav-toggle { display: inline-flex; }
  .nav-cta { display: none; }
  .theme-btn { padding: 0 10px; }
  .theme-btn .t-label { display: none; }
  .nav-links {
    position: fixed; top: 72px; left: 0; right: 0;
    flex-direction: column; gap: 0; margin: 0;
    background: rgba(var(--nav-rgb), .98); border-bottom: 1px solid var(--line-soft);
    max-height: 0; overflow: hidden; transition: max-height .35s var(--ease);
  }
  .nav-links.is-open { max-height: 420px; }
  .nav-links a { padding: 15px 26px; border-top: 1px solid rgba(var(--accent-rgb), .07); }
  .nav-links a::after { display: none; }
  .sec { padding: 60px 0; }
  .page-banner { height: 320px; }
}
@media (max-width: 560px) {
  .footer-grid { grid-template-columns: 1fr; gap: 28px; }
  .btn { padding: 12px 28px; font-size: 16px; }
  .sec-head h2 { letter-spacing: 6px; }
}

/* 减少动态效果 */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .01ms !important; transition-duration: .01ms !important; }
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; }
}