/* ==========================================================================
   AI Nexus 国际站  —  www.useainexus.com
   设计方向："深空轨道"（Deep Orbit）
   深藏青与纯白明暗交替，亮科技蓝为唯一强调色，
   等宽字体点缀数字与代码，轨道环元素呼应品牌 LOGO。
   三语共用同一份样式：locale 差异只通过 html[lang] 覆盖字体栈与排版细节。
   ========================================================================== */

/* ---------- 设计变量 ---------- */
:root {
  /* 颜色 */
  --ink: #0B1220;            /* 主深色（近黑藏青） */
  --ink-2: #0F172A;          /* 深藏青 */
  --ink-soft: #1B2740;       /* 深色区域卡片 */
  --line-dark: rgba(148, 178, 255, .14);
  --blue: #1A6EF5;           /* 品牌主蓝 */
  --blue-bright: #4D8DFF;    /* 深底亮蓝 */
  --blue-glow: rgba(26, 110, 245, .35);
  --white: #FFFFFF;
  --bg-light: #F5F8FE;       /* 浅色区域底 */
  --text-dark: #16233B;      /* 浅色区正文 */
  --text-mute: #5A6B85;      /* 浅色区次要文字 */
  --text-light: #E8EFFC;     /* 深色区正文 */
  --text-light-mute: #93A5C4;/* 深色区次要文字 */
  --line-light: #DEE7F7;

  /* 字体（默认给中文简体的 locale 使用，英文与繁体在下方按 html[lang] 覆盖） */
  --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "HarmonyOS Sans SC",
               "Microsoft YaHei", "Segoe UI", Roboto, sans-serif;
  --font-mono: "SF Mono", "Cascadia Code", "JetBrains Mono", Consolas, "Courier New", monospace;

  /* 节奏 */
  --radius: 14px;
  --radius-lg: 20px;
  --container: 1140px;
  --nav-h: 72px;
  --ease: cubic-bezier(.22, .61, .2, 1);
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* ---------- Locale 排版覆盖 ----------
   同一组件三语共用，仅字体栈与行高/字距按语言微调，
   避免为英文长词把中文站的紧凑排版直接搬过来。 */
html[lang="en"] {
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue",
               Arial, "Noto Sans", sans-serif;
}
html[lang="zh-TW"] {
  --font-sans: -apple-system, BlinkMacSystemFont, "PingFang TC", "HarmonyOS Sans TC",
               "Microsoft JhengHei", "Noto Sans TC", "Segoe UI", sans-serif;
}

html[lang="en"] body { line-height: 1.65; }
html[lang="en"] h1, html[lang="en"] h2 { letter-spacing: -.02em; }
/* 英文长词（模型名、URL）不得溢出卡片：允许任意位置断词并启用软连字符 */
html[lang="en"] .cap-card p,
html[lang="en"] .model-note,
html[lang="en"] .price-note,
html[lang="en"] .tier-list li,
html[lang="en"] .flow-step p,
html[lang="en"] .contact-value,
html[lang="en"] .contact-note,
html[lang="en"] .hero-title,
html[lang="en"] .section-head h2 { overflow-wrap: anywhere; hyphens: auto; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  color: var(--text-dark);
  background: var(--white);
  line-height: 1.75;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

.mono { font-family: var(--font-mono); letter-spacing: .04em; }

/* 滚动锚点定位补偿 */
section[id], #hero { scroll-margin-top: calc(var(--nav-h) + 8px); }

/* ---------- 布局通用 ---------- */
.container {
  width: min(var(--container), calc(100% - 48px));
  margin-inline: auto;
}

.section { padding: clamp(72px, 10vw, 120px) 0; position: relative; }
.section-light { background: var(--white); }
.section-dark { background: var(--ink); color: var(--text-light); overflow: hidden; }

.section-head { max-width: 640px; margin-bottom: clamp(40px, 6vw, 64px); }
.section-head h2 {
  font-size: clamp(1.9rem, 3.6vw, 2.7rem);
  font-weight: 800;
  letter-spacing: .01em;
  line-height: 1.25;
  margin: 10px 0 14px;
}
.section-desc { color: var(--text-mute); font-size: 1.02rem; }
.section-head-dark h2 { color: var(--white); }
.section-head-dark .section-desc { color: var(--text-light-mute); }

.section-no {
  font-size: .78rem;
  color: var(--blue);
  text-transform: uppercase;
  display: inline-flex;
  align-items: center;
  gap: 10px;
}
.section-no::after {
  content: "";
  width: 48px; height: 1px;
  background: linear-gradient(90deg, var(--blue), transparent);
}
.section-head-dark .section-no { color: var(--blue-bright); }
.section-head-dark .section-no::after { background: linear-gradient(90deg, var(--blue-bright), transparent); }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-weight: 600;
  font-size: .95rem;
  padding: 12px 26px;
  border-radius: 999px;
  transition: transform .25s var(--ease), box-shadow .25s var(--ease),
              background .25s var(--ease), border-color .25s var(--ease), color .25s var(--ease);
  white-space: nowrap;
}
.btn:active { transform: scale(.97); }

.btn-primary {
  background: linear-gradient(135deg, #2E7CF6, var(--blue));
  color: var(--white);
  box-shadow: 0 8px 24px -8px var(--blue-glow), inset 0 1px 0 rgba(255,255,255,.25);
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 14px 32px -8px rgba(26, 110, 245, .55), inset 0 1px 0 rgba(255,255,255,.25);
}

.btn-ghost { border: 1px solid var(--line-light); color: var(--text-dark); background: var(--white); }
.btn-ghost:hover { border-color: var(--blue); color: var(--blue); transform: translateY(-2px); }

.btn-ghost.dark-ghost,
.btn-outline-light { border: 1px solid rgba(148, 178, 255, .35); color: var(--text-light); background: transparent; }
.btn-outline-light:hover { border-color: var(--blue-bright); color: var(--blue-bright); transform: translateY(-2px); }

.btn-sm { padding: 9px 20px; font-size: .88rem; }
.btn-lg { padding: 15px 36px; font-size: 1rem; }
.btn-block { width: 100%; }

/* ---------- 入场动画（仅在 html.js 时隐藏待入场元素，无 JS 环境保持完全可见） ---------- */
html.js .reveal {
  opacity: 0;
  transform: translateY(26px);
  transition: opacity .7s var(--ease), transform .7s var(--ease);
}
html.js .reveal[data-delay="1"] { transition-delay: .07s; }
html.js .reveal[data-delay="2"] { transition-delay: .14s; }
html.js .reveal[data-delay="3"] { transition-delay: .21s; }
html.js .reveal[data-delay="4"] { transition-delay: .28s; }
html.js .reveal[data-delay="5"] { transition-delay: .35s; }
html.js .reveal[data-delay="6"] { transition-delay: .42s; }
html.js .reveal.is-visible { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal, html.js .reveal { opacity: 1; transform: none; transition: none; }
  * { animation-duration: .01ms !important; animation-iteration-count: 1 !important; }
}

/* ==========================================================================
   顶部导航
   ========================================================================== */
.site-nav {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 100;
  height: var(--nav-h);
  background: rgba(11, 18, 32, .72);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid rgba(148, 178, 255, .1);
  transition: box-shadow .3s var(--ease);
}
.site-nav.is-scrolled { box-shadow: 0 12px 32px -16px rgba(2, 8, 20, .8); }

.nav-inner {
  width: min(1200px, calc(100% - 40px));
  margin-inline: auto;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.nav-brand { display: flex; align-items: center; gap: 12px; }
.nav-logo { width: 36px; height: 36px; }
.nav-brand-text { display: flex; flex-direction: column; line-height: 1.2; }
.nav-brand-text strong { color: var(--white); font-size: 1.05rem; letter-spacing: .06em; }
.nav-brand-text em {
  font-style: normal;
  font-family: var(--font-mono);
  font-size: .62rem;
  letter-spacing: .32em;
  color: var(--blue-bright);
}

.nav-links { display: flex; gap: 6px; }
.nav-links a {
  position: relative;
  color: rgba(232, 239, 252, .78);
  font-size: .92rem;
  padding: 8px 14px;
  border-radius: 8px;
  transition: color .2s, background .2s;
}
.nav-links a:hover { color: var(--white); background: rgba(148, 178, 255, .08); }
.nav-links a.is-active { color: var(--white); }
.nav-links a.is-active::after {
  content: "";
  position: absolute;
  left: 14px; right: 14px; bottom: 2px;
  height: 2px;
  border-radius: 2px;
  background: var(--blue-bright);
}

.nav-actions { display: flex; align-items: center; gap: 14px; }

/* 移动端汉堡 */
.nav-toggle { display: none; width: 40px; height: 40px; flex-direction: column; justify-content: center; gap: 5px; padding: 8px; }
.nav-toggle span {
  display: block; height: 2px; border-radius: 2px;
  background: var(--white);
  transition: transform .3s var(--ease), opacity .3s;
}
.nav-toggle.is-open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.is-open span:nth-child(2) { opacity: 0; }
.nav-toggle.is-open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ==========================================================================
   Hero 首屏
   ========================================================================== */
.hero {
  position: relative;
  /* 撑满首屏，但在高分屏/整页截图窗口下不无限拉伸（内容居中，超过 980px 只会留白） */
  min-height: min(100vh, 980px);
  min-height: min(100svh, 980px);
  display: flex;
  align-items: center;
  background:
    radial-gradient(ellipse 900px 520px at 78% 8%, rgba(26, 110, 245, .22), transparent 62%),
    radial-gradient(ellipse 700px 460px at 8% 92%, rgba(26, 110, 245, .12), transparent 60%),
    linear-gradient(180deg, #0C1424 0%, var(--ink) 58%, #0C1220 100%);
  color: var(--text-light);
  padding: calc(var(--nav-h) + 48px) 0 96px;
  overflow: hidden;
}

/* 细网格背景 */
.hero-grid {
  position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(148, 178, 255, .05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(148, 178, 255, .05) 1px, transparent 1px);
  background-size: 56px 56px;
  -webkit-mask-image: radial-gradient(ellipse 75% 65% at 50% 42%, #000 30%, transparent 78%);
  mask-image: radial-gradient(ellipse 75% 65% at 50% 42%, #000 30%, transparent 78%);
}

.hero-glow {
  position: absolute;
  left: 50%; top: 44%;
  width: 560px; height: 560px;
  transform: translate(-50%, -50%);
  background: radial-gradient(circle, rgba(26, 110, 245, .16), transparent 65%);
  filter: blur(10px);
  pointer-events: none;
}

/* 轨道环装饰（呼应 LOGO） */
.hero-orbits {
  position: absolute;
  right: -180px; top: 50%;
  width: 820px; height: 820px;
  transform: translateY(-50%);
  opacity: .5;
  pointer-events: none;
}
.orbit-svg { width: 100%; height: 100%; overflow: visible; }
.orbit-ring { fill: none; stroke: rgba(148, 178, 255, .22); stroke-width: 1.2; }
.orbit-r1 { transform-origin: 400px 400px; animation: orbit-spin 46s linear infinite; }
.orbit-r2 { transform-origin: 400px 400px; animation: orbit-spin 32s linear infinite reverse; stroke: rgba(77, 141, 255, .3); }
.orbit-r3 { transform-origin: 400px 400px; animation: orbit-spin 24s linear infinite; stroke: rgba(77, 141, 255, .4); }
.orbit-dot { fill: var(--blue-bright); }
.orbit-d1 { transform-origin: 400px 400px; animation: orbit-spin 32s linear infinite reverse; }
.orbit-d2 { transform-origin: 400px 400px; animation: orbit-spin 46s linear infinite; }

@keyframes orbit-spin { to { transform: rotate(360deg); } }

.hero-inner { position: relative; z-index: 2; width: min(var(--container), calc(100% - 48px)); margin-inline: auto; }

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 7px 16px;
  border: 1px solid rgba(148, 178, 255, .22);
  border-radius: 999px;
  background: rgba(27, 39, 64, .55);
  font-size: .78rem;
  color: var(--text-light-mute);
}
.hero-badge .mono { color: var(--blue-bright); }
.badge-divider { width: 1px; height: 12px; background: rgba(148, 178, 255, .3); }

/* 徽章前的呼吸点：取品牌蓝而非“正常/故障”绿，避免静态页被误读成实时监控状态 */
.pulse-dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--blue-bright);
  position: relative;
}
.pulse-dot::after {
  content: "";
  position: absolute; inset: -4px;
  border-radius: 50%;
  border: 1px solid rgba(77, 141, 255, .55);
  animation: pulse-ring 1.8s var(--ease) infinite;
}
@keyframes pulse-ring {
  0% { transform: scale(.6); opacity: 1; }
  100% { transform: scale(1.7); opacity: 0; }
}

.hero-mark { margin: 30px 0 22px; }
.hero-mark img {
  width: 88px; height: 88px;
  filter: drop-shadow(0 12px 32px rgba(26, 110, 245, .45));
}

.hero-title {
  font-size: clamp(2.6rem, 6.4vw, 4.6rem);
  font-weight: 900;
  line-height: 1.14;
  letter-spacing: .01em;
}
.grad-text {
  background: linear-gradient(100deg, #6EA8FF 0%, var(--blue) 55%, #8FB8FF 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-sub-en {
  margin-top: 16px;
  color: var(--blue-bright);
  font-size: clamp(.82rem, 1.6vw, .95rem);
  letter-spacing: .42em;
  text-transform: uppercase;
}

.hero-desc {
  margin-top: 20px;
  max-width: 560px;
  color: var(--text-light-mute);
  font-size: 1.05rem;
}

.hero-cta { margin-top: 36px; display: flex; flex-wrap: wrap; gap: 14px; }
.hero-cta .btn-ghost { background: rgba(27, 39, 64, .4); border-color: rgba(148, 178, 255, .28); color: var(--text-light); }
.hero-cta .btn-ghost:hover { border-color: var(--blue-bright); color: var(--blue-bright); }

/* 数据统计 */
.hero-stats {
  margin-top: clamp(44px, 7vw, 72px);
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
  max-width: 720px;
  border-top: 1px solid rgba(148, 178, 255, .14);
  padding-top: 28px;
}
.stat dt {
  font-size: clamp(1.5rem, 3vw, 2.1rem);
  font-weight: 700;
  color: var(--white);
}
.stat dd { font-size: .84rem; color: var(--text-light-mute); margin-top: 2px; }

/* 向下滚动提示（纯装饰动画线） */
.hero-scroll {
  position: absolute;
  left: 50%; bottom: 26px;
  transform: translateX(-50%);
  display: flex; flex-direction: column; align-items: center;
  pointer-events: none;
  z-index: 2;
}
.scroll-line {
  width: 1px; height: 44px;
  background: linear-gradient(180deg, var(--blue-bright), transparent);
  overflow: hidden;
  animation: scroll-drip 2s var(--ease) infinite;
}
@keyframes scroll-drip {
  0% { transform: scaleY(0); transform-origin: top; }
  45% { transform: scaleY(1); transform-origin: top; }
  55% { transform: scaleY(1); transform-origin: bottom; }
  100% { transform: scaleY(0); transform-origin: bottom; }
}

/* ==========================================================================
   核心能力（浅色）
   ========================================================================== */
.cap-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
}

.cap-card {
  position: relative;
  background: var(--white);
  border: 1px solid var(--line-light);
  border-radius: var(--radius-lg);
  padding: 30px 28px;
  transition: transform .35s var(--ease), box-shadow .35s var(--ease), border-color .35s var(--ease);
  overflow: hidden;
}
.cap-card::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 3px;
  background: linear-gradient(90deg, var(--blue), transparent);
  opacity: 0;
  transition: opacity .35s var(--ease);
}
.cap-card:hover {
  transform: translateY(-6px);
  border-color: rgba(26, 110, 245, .4);
  box-shadow: 0 24px 48px -20px rgba(22, 35, 59, .18);
}
.cap-card:hover::before { opacity: 1; }

.cap-icon {
  width: 52px; height: 52px;
  border-radius: 14px;
  display: grid; place-items: center;
  background: linear-gradient(135deg, rgba(26, 110, 245, .12), rgba(26, 110, 245, .04));
  border: 1px solid rgba(26, 110, 245, .22);
  margin-bottom: 20px;
  transition: transform .35s var(--ease), background .35s var(--ease);
}
.cap-icon svg {
  width: 26px; height: 26px;
  fill: none;
  stroke: var(--blue);
  stroke-width: 1.7;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.cap-card:hover .cap-icon {
  transform: scale(1.06) rotate(-3deg);
  background: linear-gradient(135deg, var(--blue), #2E7CF6);
  border-color: transparent;
}
.cap-card:hover .cap-icon svg { stroke: var(--white); }

.cap-card h3 { font-size: 1.12rem; font-weight: 700; margin-bottom: 8px; }
.cap-card p { color: var(--text-mute); font-size: .93rem; }

/* ==========================================================================
   模型矩阵（深色）
   ========================================================================== */
.models-glow {
  position: absolute;
  right: -220px; top: -120px;
  width: 640px; height: 640px;
  background: radial-gradient(circle, rgba(26, 110, 245, .16), transparent 65%);
  pointer-events: none;
}
.glow-alt { right: auto; left: -220px; top: auto; bottom: -160px; }

.model-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
  position: relative;
  z-index: 1;
}

.model-card {
  display: flex;
  flex-direction: column;
  background: linear-gradient(180deg, rgba(27, 39, 64, .72), rgba(15, 23, 42, .5));
  border: 1px solid var(--line-dark);
  border-radius: var(--radius-lg);
  padding: 30px 28px;
  transition: transform .35s var(--ease), border-color .35s var(--ease), box-shadow .35s var(--ease);
}
.model-card:hover {
  transform: translateY(-6px);
  border-color: rgba(77, 141, 255, .5);
  box-shadow: 0 28px 56px -24px rgba(2, 8, 20, .9);
}
.model-card-accent { border-color: rgba(77, 141, 255, .35); }
.model-card-accent:hover { border-color: rgba(77, 141, 255, .7); }

.model-tag {
  display: inline-block;
  align-self: flex-start;
  font-size: .68rem;
  letter-spacing: .22em;
  color: var(--blue-bright);
  border: 1px solid rgba(77, 141, 255, .35);
  padding: 4px 12px;
  border-radius: 999px;
  margin-bottom: 16px;
}
.model-card h3 { color: var(--white); font-size: 1.3rem; font-weight: 800; }
.model-card-head > p { color: var(--text-light-mute); font-size: .88rem; margin: 6px 0 20px; }

.model-list { flex: 1; border-top: 1px solid var(--line-dark); }
.model-list li {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  padding: 11px 0;
  border-bottom: 1px dashed rgba(148, 178, 255, .12);
  transition: padding-left .25s var(--ease);
}
.model-list li:hover { padding-left: 8px; }
.model-name { color: var(--white); font-size: .92rem; font-weight: 600; }
.model-note { color: var(--text-light-mute); font-size: .78rem; text-align: right; }

.model-foot {
  margin-top: 18px;
  font-size: .82rem;
  line-height: 1.7;
  color: var(--text-light-mute);
  padding: 12px 14px;
  border-radius: 10px;
  background: rgba(11, 18, 32, .5);
  border-left: 2px solid var(--blue);
}
/* 矩阵下方统一声明：模型经上游授权渠道接入 */
.model-footnote {
  margin: 30px auto 0;
  width: min(760px, 100%);
  text-align: center;
  font-size: .84rem;
  line-height: 1.7;
  color: var(--text-light-mute);
}

/* ==========================================================================
   计费口径（浅色；只讲计量单位，不列金额与折扣）
   ========================================================================== */
.price-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
}

.price-card {
  position: relative;
  padding: 34px 30px 30px;
  border-radius: var(--radius-lg);
  background: var(--bg-light);
  border: 1px solid var(--line-light);
  overflow: hidden;
  transition: transform .35s var(--ease), box-shadow .35s var(--ease);
}
.price-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 24px 48px -22px rgba(22, 35, 59, .22);
}
.price-card::after {
  content: "";
  position: absolute;
  right: -60px; top: -60px;
  width: 160px; height: 160px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(26, 110, 245, .14), transparent 70%);
}

.price-label { font-size: .9rem; color: var(--text-mute); }
.price-value { margin: 8px 0 10px; line-height: 1; display: flex; align-items: baseline; gap: 6px; }
.price-num {
  font-size: clamp(3.2rem, 6vw, 4.6rem);
  font-weight: 700;
  background: linear-gradient(120deg, var(--blue) 20%, #6EA8FF);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.price-unit { font-size: 1.05rem; font-weight: 700; color: var(--text-dark); }
.price-note { font-size: .88rem; color: var(--text-mute); position: relative; }

.price-banner {
  margin-top: 26px;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  border: 1px solid var(--line-light);
  border-radius: var(--radius);
  background: var(--white);
  overflow: hidden;
}
.price-banner-item {
  padding: 20px 22px;
  font-size: .92rem;
  color: var(--text-dark);
  display: flex;
  align-items: center;
  gap: 12px;
}
.price-banner-item + .price-banner-item { border-left: 1px solid var(--line-light); }
.price-banner-item .mono {
  color: var(--blue);
  font-weight: 700;
  font-size: .8rem;
  letter-spacing: .08em;
  /* 单位标签是 flex 子项：右侧说明文字一长，它就被压缩到折行（“/” 与 “TOKEN” 断开）。
     标签必须不折行也不参与收缩，让说明文字自己换行。 */
  flex: none;
  white-space: nowrap;
}

.price-footnote {
  margin-top: 18px;
  text-align: center;
  font-size: .8rem;
  color: var(--text-mute);
}

/* ==========================================================================
   用量与赠送方案（深色；海外站不公开标价，卡片不出现金额）
   ========================================================================== */
.tier-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 20px;
  align-items: stretch;
}
/* 三张无金额方案卡：三等分且单卡更宽，避免沿用四档金额卡时的拥挤比例 */
.tier-grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 24px; }

.tier-card {
  position: relative;
  display: flex;
  flex-direction: column;
  background: linear-gradient(180deg, rgba(27, 39, 64, .72), rgba(15, 23, 42, .5));
  border: 1px solid var(--line-dark);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  transition: transform .35s var(--ease), border-color .35s var(--ease), box-shadow .35s var(--ease);
}
.tier-card:hover {
  transform: translateY(-6px);
  border-color: rgba(77, 141, 255, .55);
  box-shadow: 0 28px 56px -24px rgba(2, 8, 20, .9);
}

.tier-name { font-size: .95rem; color: var(--text-light-mute); }
.tier-tagline {
  margin: 8px 0 4px;
  font-size: .72rem;
  letter-spacing: .18em;
  color: var(--blue-bright);
  text-transform: uppercase;
}
.tier-price {
  margin: 10px 0 4px;
  font-size: clamp(1.7rem, 2.6vw, 2.1rem);
  font-weight: 700;
  color: var(--white);
}
.tier-bonus { font-size: .86rem; color: var(--text-light-mute); }
.tier-bonus strong { color: var(--blue-bright); font-size: 1.05em; }

.tier-list { flex: 1; margin: 20px 0 24px; border-top: 1px solid var(--line-dark); }
.tier-list li {
  position: relative;
  padding: 9px 0 9px 20px;
  font-size: .85rem;
  color: var(--text-light-mute);
  border-bottom: 1px dashed rgba(148, 178, 255, .12);
}
.tier-list li::before {
  content: "";
  position: absolute;
  left: 2px; top: 16px;
  width: 7px; height: 7px;
  border-radius: 50%;
  background: var(--blue-bright);
  box-shadow: 0 0 8px rgba(77, 141, 255, .8);
}

.tier-card-hot {
  background: linear-gradient(180deg, rgba(26, 110, 245, .2), rgba(15, 23, 42, .6));
  border-color: rgba(77, 141, 255, .6);
  box-shadow: 0 0 0 1px rgba(77, 141, 255, .18), 0 24px 60px -24px rgba(26, 110, 245, .4);
}
.tier-card-hot:hover { border-color: var(--blue-bright); }

.tier-badge {
  position: absolute;
  top: -13px; left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(135deg, #2E7CF6, var(--blue));
  color: var(--white);
  font-size: .74rem;
  font-weight: 600;
  padding: 5px 16px;
  border-radius: 999px;
  box-shadow: 0 8px 20px -6px var(--blue-glow);
  white-space: nowrap;
}

.tier-card-max { border-color: rgba(143, 184, 255, .35); }

.tier-note {
  margin-top: 28px;
  text-align: center;
  font-size: .82rem;
  color: var(--text-light-mute);
  position: relative;
  z-index: 1;
}
.tier-note-sub { margin-top: 10px; }

/* ==========================================================================
   使用流程（浅色）
   ========================================================================== */
.flow-list {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 22px;
  counter-reset: flow;
  margin-bottom: 40px;
}

.flow-step {
  position: relative;
  padding: 26px 24px;
  border-radius: var(--radius);
  background: var(--bg-light);
  border: 1px solid var(--line-light);
  transition: transform .35s var(--ease), border-color .35s var(--ease), box-shadow .35s var(--ease);
}
.flow-step:hover {
  transform: translateY(-5px);
  border-color: rgba(26, 110, 245, .45);
  box-shadow: 0 20px 40px -20px rgba(22, 35, 59, .2);
}
.flow-step:not(:last-child)::after {
  content: "";
  position: absolute;
  top: 50%; right: -22px;
  width: 22px; height: 1px;
  background: repeating-linear-gradient(90deg, var(--blue) 0 4px, transparent 4px 8px);
  opacity: .6;
}

.flow-no {
  font-size: .8rem;
  font-weight: 700;
  color: var(--blue);
  display: inline-block;
  margin-bottom: 12px;
  padding: 3px 10px;
  border-radius: 6px;
  background: rgba(26, 110, 245, .1);
}
.flow-step h3 { font-size: 1.05rem; font-weight: 700; margin-bottom: 6px; }
.flow-step p { font-size: .86rem; color: var(--text-mute); }

/* 代码示例 */
.code-sample {
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: var(--ink);
  border: 1px solid var(--line-dark);
  box-shadow: 0 32px 64px -28px rgba(22, 35, 59, .45);
  max-width: 780px;
}
.code-head {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 13px 18px;
  background: rgba(27, 39, 64, .8);
  border-bottom: 1px solid var(--line-dark);
}
.code-head .dot { width: 10px; height: 10px; border-radius: 50%; background: rgba(148, 178, 255, .25); }
.code-head .dot:first-child { background: #FF5F57; }
.code-head .dot:nth-child(2) { background: #FEBC2E; }
.code-head .dot:nth-child(3) { background: #28C840; }
.code-title { margin-left: 10px; font-size: .74rem; color: var(--text-light-mute); }

.code-sample pre {
  padding: 24px 22px;
  overflow-x: auto;
  font-size: .84rem;
  line-height: 1.9;
  color: #C9D8F5;
}
.code-sample code .c-key { color: #7FB0FF; }
.code-sample code .c-str { color: #7CE0A6; }
.code-sample code .c-cmt { color: #64779B; }
.code-sample code .c-fn { color: #9FB6FF; }
.code-sample code .c-num { color: #FFB86C; }

/* ==========================================================================
   联系我们（深色）
   ========================================================================== */
.section-contact { padding-bottom: clamp(88px, 12vw, 140px); }
.contact-glow {
  position: absolute;
  left: 50%; bottom: -280px;
  transform: translateX(-50%);
  width: 900px; height: 520px;
  background: radial-gradient(ellipse, rgba(26, 110, 245, .18), transparent 65%);
  pointer-events: none;
}

.contact-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
  position: relative;
  z-index: 1;
}

.contact-card {
  padding: 30px 28px;
  border-radius: var(--radius-lg);
  background: linear-gradient(180deg, rgba(27, 39, 64, .72), rgba(15, 23, 42, .5));
  border: 1px solid var(--line-dark);
  transition: transform .35s var(--ease), border-color .35s var(--ease);
}
.contact-card:hover { transform: translateY(-6px); border-color: rgba(77, 141, 255, .55); }
.contact-card h3 { color: var(--white); font-size: 1.08rem; margin-bottom: 14px; }
.contact-label { font-size: .68rem; letter-spacing: .26em; color: var(--blue-bright); }
.contact-value { font-size: 1.18rem; font-weight: 600; color: var(--white); margin: 6px 0 10px; }
.contact-value a { transition: color .2s; }
.contact-value a:hover { color: var(--blue-bright); }
.contact-note { font-size: .82rem; color: var(--text-light-mute); }

/* ==========================================================================
   页脚
   ========================================================================== */
.site-footer {
  background: #070D18;
  color: var(--text-light-mute);
  border-top: 1px solid rgba(148, 178, 255, .1);
  padding: 44px 0 30px;
  font-size: .86rem;
}
.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
  padding-bottom: 26px;
  border-bottom: 1px solid rgba(148, 178, 255, .1);
}
.footer-brand { display: flex; align-items: center; gap: 12px; }
.footer-brand img { width: 32px; height: 32px; opacity: .9; }
.footer-name { color: var(--text-light); }
.footer-slogan { font-family: var(--font-mono); font-size: .7rem; letter-spacing: .2em; color: var(--blue-bright); }

.footer-links { display: flex; flex-wrap: wrap; gap: 6px 22px; }
.footer-links a { transition: color .2s; }
.footer-links a:hover { color: var(--blue-bright); }

.footer-meta {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 10px;
  padding-top: 22px;
  font-size: .8rem;
}
.footer-meta .mono { font-size: .74rem; letter-spacing: .08em; }
/* 运营主体（香港实体）与两站独立声明 */
.footer-entity { color: var(--text-light-mute); }
.footer-note {
  max-width: 72ch;
  line-height: 1.7;
  color: rgba(147, 165, 196, .72);
  font-size: .76rem;
}
/* 深底页脚中的占位高亮（浅蓝底会完全看不清） */
.site-footer mark.ph {
  background: rgba(77, 141, 255, .22);
  color: #BFD4FF;
}

.footer-legal { display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 18px; }
.footer-legal a { transition: color .2s; }
.footer-legal a:hover { color: var(--blue-bright); }

/* ==========================================================================
   法务页面（服务条款 / 充值与退款规则 / 隐私政策）
   复用主站设计变量、导航与页脚结构；正文为窄栏阅读版式。
   ========================================================================== */
.legal-hero {
  position: relative;
  overflow: hidden;
  padding: calc(var(--nav-h) + clamp(48px, 8vw, 84px)) 0 clamp(56px, 8vw, 84px);
  background:
    radial-gradient(ellipse 760px 420px at 82% 0%, rgba(26, 110, 245, .22), transparent 62%),
    linear-gradient(180deg, #0C1424 0%, var(--ink) 100%);
  color: var(--text-light);
}
.legal-hero-grid {
  position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(148, 178, 255, .05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(148, 178, 255, .05) 1px, transparent 1px);
  background-size: 56px 56px;
  -webkit-mask-image: radial-gradient(ellipse 78% 92% at 50% 0%, #000 34%, transparent 82%);
  mask-image: radial-gradient(ellipse 78% 92% at 50% 0%, #000 34%, transparent 82%);
}
.legal-hero-glow {
  position: absolute;
  right: -160px; top: -180px;
  width: 520px; height: 520px;
  background: radial-gradient(circle, rgba(26, 110, 245, .18), transparent 65%);
  filter: blur(10px);
  pointer-events: none;
}
.legal-hero-inner {
  position: relative; z-index: 1;
  width: min(840px, calc(100% - 48px));
  margin-inline: auto;
}
.legal-crumb {
  display: flex; align-items: center; gap: 10px;
  font-size: .74rem; letter-spacing: .12em;
  color: var(--text-light-mute);
}
.legal-crumb a { color: var(--blue-bright); transition: color .2s; }
.legal-crumb a:hover { color: var(--white); }
.crumb-sep { color: rgba(147, 165, 196, .5); }
.legal-eyebrow {
  margin-top: 26px;
  font-size: .74rem;
  letter-spacing: .38em;
  text-transform: uppercase;
  color: var(--blue-bright);
}
.legal-title {
  margin: 14px 0 12px;
  font-size: clamp(2.1rem, 4.8vw, 3rem);
  font-weight: 900;
  line-height: 1.2;
  letter-spacing: .02em;
  color: var(--white);
}
.legal-date {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 6px 14px;
  border: 1px solid rgba(148, 178, 255, .22);
  border-radius: 999px;
  background: rgba(27, 39, 64, .55);
  font-size: .78rem;
  letter-spacing: .1em;
  color: var(--text-light-mute);
}
.legal-date::before {
  content: "";
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--blue-bright);
  box-shadow: 0 0 8px rgba(77, 141, 255, .8);
}

/* 法务表格内的链接（邮箱 / 条款内锚点） */
.legal-table a { color: var(--blue); font-weight: 600; text-decoration: underline; text-underline-offset: 3px; }

/* [占位] 标注高亮 */
mark {
  background: rgba(26, 110, 245, .1);
  color: var(--blue);
  padding: 1px 7px;
  border-radius: 5px;
  font-size: .92em;
  font-weight: 600;
}

/* 窄栏正文 */
.legal-body {
  width: min(800px, calc(100% - 48px));
  margin-inline: auto;
  padding: clamp(44px, 6vw, 64px) 0 clamp(72px, 9vw, 104px);
  color: #42536F;
}

/* 本页目录 */
.legal-toc {
  background: var(--bg-light);
  border: 1px solid var(--line-light);
  border-radius: var(--radius-lg);
  padding: 26px 28px;
  margin-bottom: clamp(40px, 5vw, 56px);
}
.legal-toc-title {
  font-size: .72rem;
  letter-spacing: .28em;
  text-transform: uppercase; /* 英文页得到 CONTENTS 观感，CJK 文本不受影响 */
  color: var(--blue);
  margin-bottom: 14px;
}
.legal-toc ol { counter-reset: toc; display: grid; gap: 2px; }
.legal-toc a {
  display: flex; align-items: baseline; gap: 12px;
  padding: 7px 12px;
  border-radius: 8px;
  font-size: .92rem;
  color: var(--text-mute);
  transition: color .2s, background .2s;
}
.legal-toc a::before {
  counter-increment: toc;
  content: counter(toc, decimal-leading-zero);
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .06em;
  color: var(--blue);
}
.legal-toc a:hover { color: var(--blue); background: rgba(26, 110, 245, .07); }

/* 条款章节 */
.legal-section {
  margin-top: clamp(38px, 5vw, 54px);
  scroll-margin-top: calc(var(--nav-h) + 16px);
}
.legal-section h2 {
  display: flex; align-items: center; gap: 12px;
  margin-bottom: 18px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--line-light);
  font-size: clamp(1.26rem, 2.4vw, 1.5rem);
  font-weight: 800;
  line-height: 1.4;
  color: var(--text-dark);
}
.legal-section h2::before {
  content: "";
  flex: none;
  width: 4px; height: 1.15em;
  border-radius: 3px;
  background: linear-gradient(180deg, var(--blue), #6EA8FF);
}
.legal-section h3 {
  margin: 26px 0 10px;
  font-size: 1.04rem;
  font-weight: 700;
  color: var(--text-dark);
}
.legal-section p { margin: 12px 0; font-size: .94rem; line-height: 1.95; }
.legal-section ul { margin: 12px 0; display: grid; gap: 9px; }
.legal-section ul li {
  position: relative;
  padding-left: 20px;
  font-size: .94rem;
  line-height: 1.85;
}
.legal-section ul li::before {
  content: "";
  position: absolute;
  left: 4px; top: .68em;
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--blue);
  opacity: .7;
}
.legal-steps { margin: 14px 0; counter-reset: step; display: grid; gap: 12px; }
.legal-steps li {
  position: relative;
  padding-left: 40px;
  font-size: .94rem;
  line-height: 1.85;
  counter-increment: step;
}
.legal-steps li::before {
  content: counter(step, decimal-leading-zero);
  position: absolute;
  left: 0; top: .12em;
  padding: 3px 7px;
  border-radius: 6px;
  background: rgba(26, 110, 245, .1);
  font-family: var(--font-mono);
  font-size: .72rem;
  font-weight: 700;
  color: var(--blue);
}

/* 表格 */
.legal-table-wrap {
  margin: 16px 0;
  border: 1px solid var(--line-light);
  border-radius: 12px;
  overflow-x: auto;
}
.legal-table {
  width: 100%;
  border-collapse: collapse;
  font-size: .9rem;
  min-width: 560px;
}
.legal-table th, .legal-table td {
  padding: 13px 16px;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--line-light);
}
.legal-table tr:last-child td { border-bottom: none; }
.legal-table th {
  background: var(--bg-light);
  color: var(--text-dark);
  font-weight: 700;
  font-size: .86rem;
  white-space: nowrap;
}
.legal-table td { color: #42536F; }
.legal-table td:first-child { font-weight: 600; color: var(--text-dark); white-space: nowrap; }

/* 重点提示框 */
.legal-callout {
  margin: 16px 0;
  padding: 14px 18px;
  border-radius: 12px;
  background: rgba(26, 110, 245, .05);
  border: 1px solid rgba(26, 110, 245, .16);
  border-left: 3px solid var(--blue);
  font-size: .9rem;
  line-height: 1.85;
}
.legal-callout strong { color: var(--blue); }

/* 文末结束符 */
.legal-end {
  display: flex; align-items: center; gap: 16px;
  margin-top: clamp(48px, 7vw, 64px);
  font-size: .78rem;
  letter-spacing: .2em;
  color: var(--text-mute);
}
.legal-end::before,
.legal-end::after {
  content: "";
  flex: 1; height: 1px;
}
.legal-end::before { background: linear-gradient(90deg, transparent, var(--line-light)); }
.legal-end::after { background: linear-gradient(90deg, var(--line-light), transparent); }

/* 页脚法务链接当前态 */
.footer-legal a.is-current { color: var(--blue-bright); font-weight: 600; }

@media (max-width: 640px) {
  .legal-toc { padding: 20px 18px; }
  .legal-eyebrow { letter-spacing: .22em; }
}

/* ==========================================================================
   响应式
   ========================================================================== */
@media (max-width: 1024px) {
  .cap-grid, .model-grid, .price-grid, .contact-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .tier-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 26px; }
  .flow-list { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .flow-step:not(:last-child)::after { display: none; }
  .hero-orbits { right: -320px; opacity: .35; }
}

@media (max-width: 820px) {
  .nav-links {
    position: fixed;
    top: var(--nav-h);
    left: 0; right: 0;
    flex-direction: column;
    gap: 4px;
    padding: 14px 20px 22px;
    background: rgba(11, 18, 32, .96);
    -webkit-backdrop-filter: blur(16px);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid rgba(148, 178, 255, .12);
    transform: translateY(-12px);
    opacity: 0;
    visibility: hidden;
    transition: transform .3s var(--ease), opacity .3s var(--ease), visibility .3s;
  }
  .nav-links.is-open { transform: none; opacity: 1; visibility: visible; }
  .nav-links a { padding: 13px 14px; font-size: 1rem; }
  .nav-links a.is-active::after { display: none; }
  .nav-toggle { display: flex; }

  .hero { padding-bottom: 72px; }
  .hero-stats { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 20px; }
  .hero-orbits { display: none; }
  .hero-scroll { display: none; }
}

@media (max-width: 640px) {
  .cap-grid, .model-grid, .price-grid, .contact-grid,
  .tier-grid, .flow-list, .price-banner { grid-template-columns: minmax(0, 1fr); }
  .price-banner-item + .price-banner-item { border-left: none; border-top: 1px solid var(--line-light); }
  .hero-cta .btn { width: 100%; }
  /* 徽章两段文案在 390 下会被挤成段内换行，分隔竖线落在两行之间：改成整段换行 + 隐藏分隔线 */
  .hero-badge { flex-wrap: wrap; row-gap: 6px; }
  .hero-badge > span:not(.badge-divider) { white-space: nowrap; }
  .badge-divider { display: none; }
  .nav-actions .btn-sm { display: none; }  /* 移动端隐藏顶栏 CTA，避免拥挤 */
  .footer-inner { flex-direction: column; align-items: flex-start; }
}

/* ==========================================================================
   多语言组件：语言切换 / 语言建议条 / 邮箱复制 / 404
   原则：语言切换在 HTML 中就是真实 <a href>，无 JS 也能完整使用；
        下拉交互只在 html.js 环境下启用。
   ========================================================================== */
[hidden] { display: none !important; }

/* ---------- 语言切换 ---------- */
.lang-switch { position: relative; }

.lang-switch-btn {
  display: none;            /* 无 JS 时不呈现控件，只保留平铺链接 */
  align-items: center;
  gap: 7px;
  padding: 7px 12px;
  border: 1px solid rgba(148, 178, 255, .28);
  border-radius: 999px;
  color: rgba(232, 239, 252, .85);
  font-size: .82rem;
  letter-spacing: .04em;
  transition: border-color .2s, color .2s, background .2s;
}
.lang-switch-btn:hover { border-color: var(--blue-bright); color: var(--white); background: rgba(148, 178, 255, .08); }
.lang-switch-btn:focus-visible,
.lang-menu a:focus-visible,
.copy-btn:focus-visible,
.lang-notice-dismiss:focus-visible,
.nav-toggle:focus-visible { outline: 2px solid var(--blue-bright); outline-offset: 2px; }

.lang-icon, .lang-caret {
  fill: none;
  stroke: currentColor;
  stroke-width: 1.4;
  stroke-linecap: round;
}
.lang-icon { width: 16px; height: 16px; }
.lang-caret { width: 11px; height: 11px; stroke-width: 1.7; transition: transform .25s var(--ease); }
.lang-current { font-family: var(--font-mono); }

.lang-menu {
  display: flex;
  align-items: center;
  gap: 2px;
  list-style: none;
}
.lang-menu a {
  display: block;
  padding: 6px 10px;
  border-radius: 8px;
  font-size: .82rem;
  color: rgba(232, 239, 252, .66);
  transition: color .2s, background .2s;
}
.lang-menu a:hover { color: var(--white); background: rgba(148, 178, 255, .1); }
.lang-menu a.is-current { color: var(--blue-bright); font-weight: 600; }

/* 页脚变体：永远平铺展示（无下拉），保证无 JS 可切换 */
.lang-switch-footer .lang-menu { flex-wrap: wrap; border-left: 1px solid rgba(148, 178, 255, .16); padding-left: 14px; }

/* 顶栏变体：脚本可用时收起为下拉菜单 */
html.js .lang-switch-nav .lang-switch-btn { display: inline-flex; }
html.js .lang-switch-nav .lang-menu {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  flex-direction: column;
  align-items: stretch;
  gap: 2px;
  min-width: 168px;
  padding: 8px;
  background: rgba(11, 18, 32, .96);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  border: 1px solid rgba(148, 178, 255, .16);
  border-radius: 12px;
  box-shadow: 0 24px 48px -24px rgba(2, 8, 20, .9);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px);
  transition: opacity .22s var(--ease), transform .22s var(--ease), visibility .22s;
  z-index: 120;
}
html.js .lang-switch-nav.is-open .lang-menu { opacity: 1; visibility: visible; transform: none; }
html.js .lang-switch-nav.is-open .lang-caret { transform: rotate(180deg); }
html.js .lang-switch-nav .lang-menu a { padding: 10px 12px; font-size: .9rem; }

/* ---------- 语言建议条（首次访问、且浏览器语言与当前语言不同时出现） ---------- */
.lang-notice {
  position: fixed;
  inset: auto 0 0 0;
  z-index: 140;
  padding: 14px 0 16px;
  background: rgba(7, 13, 24, .95);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  border-top: 1px solid rgba(148, 178, 255, .18);
  transform: translateY(110%);
  opacity: 0;
  transition: transform .35s var(--ease), opacity .35s var(--ease);
}
.lang-notice.is-visible { transform: none; opacity: 1; }

.lang-notice-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  flex-wrap: wrap;
}
.lang-notice-text { color: var(--text-light); font-size: .88rem; }
.lang-notice-actions { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.lang-notice-actions .btn-ghost { background: transparent; border-color: rgba(148, 178, 255, .3); color: var(--text-light); }
.lang-notice-actions .btn-ghost:hover { border-color: var(--blue-bright); color: var(--white); }
.lang-notice-actions .is-suggested { border-color: var(--blue-bright); color: var(--white); box-shadow: 0 0 0 1px rgba(77, 141, 255, .35); }
.lang-notice-dismiss {
  color: rgba(147, 165, 196, .8);
  font-size: .8rem;
  text-decoration: underline;
  text-underline-offset: 3px;
  padding: 6px 4px;
}
.lang-notice-dismiss:hover { color: var(--white); }

/* ---------- 复制邮箱 ---------- */
.copy-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-left: 10px;
  padding: 4px 12px;
  border: 1px solid rgba(148, 178, 255, .32);
  border-radius: 999px;
  vertical-align: middle;
  font-size: .72rem;
  letter-spacing: .06em;
  color: var(--text-light-mute);
  transition: color .2s, border-color .2s, background .2s;
}
.copy-btn:hover { color: var(--white); border-color: var(--blue-bright); background: rgba(148, 178, 255, .1); }
.copy-btn.is-done { color: #7CE0A6; border-color: rgba(124, 224, 166, .55); }
.copy-btn.is-failed { color: #FFB86C; border-color: rgba(255, 184, 108, .55); }
/* execCommand 兜底用的离屏 textarea */
.copy-fallback { position: absolute; left: -9999px; top: 0; }

/* ---------- 404 ---------- */
.nf-page { padding-top: calc(var(--nav-h) + clamp(60px, 12vw, 130px)); text-align: center; }
.nf-inner { width: min(680px, calc(100% - 48px)); }
.nf-code {
  font-size: clamp(3.6rem, 12vw, 6.2rem);
  font-weight: 700;
  letter-spacing: -.04em;
  line-height: 1;
  background: linear-gradient(135deg, var(--blue), #7FB0FF);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.nf-title { font-size: clamp(1.5rem, 4vw, 2rem); margin: 18px 0 12px; color: var(--text-dark); }
.nf-desc { color: var(--text-mute); font-size: .96rem; }
.nf-actions { display: flex; justify-content: center; gap: 14px; flex-wrap: wrap; margin-top: 30px; }
.nf-mark { margin-top: 44px; opacity: .5; }
.nf-mark img { margin-inline: auto; }

/* ---------- 占位高亮（上线前必须清零） ---------- */
mark.ph { cursor: help; }

/* ==========================================================================
   回到顶部
   ========================================================================== */
:root { --back-top-inset: 28px; --notice-h: 80px; }

.back-top {
  position: fixed;
  right: var(--back-top-inset);
  bottom: var(--back-top-inset);
  z-index: 90;
  width: 46px; height: 46px;
  display: flex; align-items: center; justify-content: center;
  border: 1px solid rgba(148, 178, 255, .28);
  border-radius: var(--radius);
  background: rgba(11, 18, 32, .72);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  color: var(--text-light);
  /* 默认隐藏：无 JS 时 .is-visible 永远不会被加上，不会给用户一个点不动的控件 */
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity .3s var(--ease), transform .3s var(--ease), visibility .3s,
              border-color .2s, color .2s, background .2s;
}
.back-top.is-visible { opacity: 1; visibility: visible; transform: none; }
.back-top:hover { border-color: var(--blue-bright); color: var(--blue-bright); background: rgba(26, 110, 245, .14); }
.back-top:focus-visible { outline: 2px solid var(--blue-bright); outline-offset: 3px; }

/* 小三角：用 border 绘制，跟随 currentColor 变色；上指三角视觉重心偏低，故光学居中上移 1px */
.back-top-tri {
  width: 0; height: 0;
  border-left: 6px solid transparent;
  border-right: 6px solid transparent;
  border-bottom: 8px solid currentColor;
  transform: translateY(-1px);
}

/* 语言建议条贴在视口底部（z-index 140），不抬高就会把「不再提示」盖住。
   --notice-h 取建议条实测高度再留几像素余量（用 /__probe/frame?notice=1 量得：
   宽屏 74~76，<=820 为 109~112，<=360 英文会多换一行到 153~176，中文恒为 112）。
   宁可调高：高了只是浮标离条子远点，低了会压住「不再提示」让人点不到。 */
.lang-notice.is-visible ~ .back-top { bottom: calc(var(--back-top-inset) + var(--notice-h)); }

@media (max-width: 820px) {
  /* 建议条改为纵向堆叠 */
  :root { --notice-h: 116px; }
}

@media (max-width: 640px) {
  :root { --back-top-inset: 16px; }
  .back-top { width: 40px; height: 40px; }
  .back-top-tri { border-left-width: 5px; border-right-width: 5px; border-bottom-width: 7px; }
}

@media (max-width: 360px) {
  /* 英文在这档宽度下文字与按钮会多换一行，中文不受影响 */
  :root { --notice-h: 180px; }
}

@media (max-width: 820px) {
  /* 窄屏仍用下拉（平铺三种语言会挤掉汉堡按钮），但菜单不能超出视口 */
  html.js .lang-switch-nav .lang-menu { min-width: 150px; max-width: 44vw; }

  .lang-notice-inner { flex-direction: column; align-items: flex-start; gap: 12px; }
  .lang-notice-actions { width: 100%; }
}

@media (prefers-reduced-motion: reduce) {
  .lang-notice, .back-top, html.js .lang-switch-nav .lang-menu { transition: none; }
}