/* ============================================================
   弦里论音乐 · 全站设计系统
   ------------------------------------------------------------
   弦里论 STRING THEORY
   视觉概念：专业音频工作台的精密感 × 本地 AI 的科技张力
   · 基色：深石墨（带冷调的炭黑），比纯黑更耐看、层次更清楚
   · 主色：暖金（专业设备面板的丝印色）
   · 辅色：青蓝（代表 AI / 技术侧，与暖金形成冷暖对照）
   ============================================================ */

/* ── 1. 设计令牌 ─────────────────────────────────────── */
:root {
  /* 背景层级 */
  --bg:        #08090b;
  --bg-1:      #0d0f12;
  --bg-2:      #13161a;
  --bg-3:      #1b1f24;
  --bg-glass:  rgba(13, 15, 18, 0.72);

  /* 品牌色 */
  --gold:      #d4b478;
  --gold-2:    #ecd39c;
  --gold-3:    #a8874e;
  --gold-soft: rgba(212, 180, 120, 0.12);
  --gold-line: rgba(212, 180, 120, 0.30);

  /* AI 辅助色 —— 与霓虹轨道 Logo 同源（取 Logo 高饱和蓝 #0A99EA） */
  --cyan:      #35a7ff;
  --cyan-2:    #7fc9ff;
  --cyan-soft: rgba(53, 167, 255, 0.12);
  --glow-cyan: 0 0 22px rgba(53, 167, 255, 0.55);

  /* 文字 */
  --text:      #f4f6f7;
  --text-2:    #a4abb3;
  --text-3:    #6d757e;

  /* 描边 */
  --border:      rgba(255, 255, 255, 0.075);
  --border-2:    rgba(255, 255, 255, 0.13);
  --border-gold: rgba(212, 180, 120, 0.26);

  /* 形状 */
  --r-sm:  6px;
  --r:     10px;
  --r-lg:  16px;
  --r-xl:  24px;
  --r-pill: 999px;

  /* 阴影 */
  --sh-1: 0 1px 2px rgba(0, 0, 0, 0.4);
  --sh-2: 0 6px 24px rgba(0, 0, 0, 0.34);
  --sh-3: 0 18px 48px rgba(0, 0, 0, 0.46);
  --glow-gold: 0 0 0 1px var(--border-gold), 0 10px 40px rgba(212, 180, 120, 0.14);

  /* 字体 */
  --font: 'PingFang SC', 'HarmonyOS Sans SC', 'Microsoft YaHei', -apple-system,
          BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --mono: ui-monospace, 'SF Mono', 'JetBrains Mono', Menlo, Consolas, monospace;

  /* 布局 */
  --pad:  clamp(20px, 5vw, 64px);
  --max:  1280px;
  --nav-h: 68px;

  /* 动效 */
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
}

/* ── 2. 基础重置 ─────────────────────────────────────── */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 15px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

/* 全局氛围：顶部暖光 + 底部冷光 */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background:
    radial-gradient(ellipse 70% 45% at 78% -8%, rgba(212, 180, 120, 0.075) 0%, transparent 62%),
    radial-gradient(ellipse 55% 40% at 8% 100%, rgba(79, 209, 197, 0.045) 0%, transparent 60%);
}

img { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button, input, select, textarea { font-family: inherit; font-size: inherit; }
::selection { background: rgba(212, 180, 120, 0.28); color: #fff; }

:focus-visible {
  outline: 2px solid var(--gold);
  outline-offset: 3px;
  border-radius: 3px;
}

/* 滚动条 */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb {
  background: var(--bg-3);
  border-radius: 99px;
  border: 2px solid var(--bg);
}
::-webkit-scrollbar-thumb:hover { background: #2a3037; }

/* ── 3. 导航 ─────────────────────────────────────────── */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 0 var(--pad);
  background: var(--bg-glass);
  backdrop-filter: blur(20px) saturate(160%);
  -webkit-backdrop-filter: blur(20px) saturate(160%);
  border-bottom: 1px solid var(--border);
  transition: background 0.3s, border-color 0.3s, box-shadow 0.3s;
}

/* 滚动后加深 */
.nav.scrolled {
  background: rgba(8, 9, 11, 0.92);
  border-bottom-color: var(--border-2);
  box-shadow: 0 1px 30px rgba(0, 0, 0, 0.5);
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 11px;
  flex-shrink: 0;
}

.nav-logo-icon {
  height: 36px;
  width: auto;
  max-width: 46px;
  object-fit: contain;
  filter: drop-shadow(0 0 10px rgba(53, 167, 255, 0.35));
  transition: transform 0.4s var(--ease);
}
.nav-logo:hover .nav-logo-icon { transform: scale(1.06) rotate(-2deg); }

.nav-logo-text {
  font-size: 16px;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--text);
}
.nav-logo-text em {
  font-style: normal;
  color: var(--gold);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
}

.nav-links a {
  position: relative;
  display: block;
  padding: 8px 13px;
  color: var(--text-2);
  font-size: 13.5px;
  letter-spacing: 0.06em;
  border-radius: var(--r-sm);
  transition: color 0.22s, background 0.22s;
}
.nav-links a:hover { color: var(--text); background: rgba(255, 255, 255, 0.045); }

/* 下划线指示 */
.nav-links a::after {
  content: '';
  position: absolute;
  left: 13px; right: 13px;
  bottom: 2px;
  height: 1px;
  background: linear-gradient(90deg, var(--gold-3), var(--gold));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.3s var(--ease);
}
.nav-links a:hover::after { transform: scaleX(1); }
.nav-links a.active { color: var(--gold); }
.nav-links a.active::after { transform: scaleX(1); }

.nav-cta {
  margin-left: 10px;
  background: linear-gradient(135deg, var(--gold-2), var(--gold));
  color: #17130a !important;
  font-weight: 700;
  letter-spacing: 0.08em;
  padding: 9px 20px !important;
  border-radius: var(--r-pill);
  box-shadow: 0 4px 18px rgba(212, 180, 120, 0.2);
  transition: transform 0.22s var(--ease), box-shadow 0.22s, filter 0.22s;
}
.nav-cta::after { display: none; }
.nav-cta:hover {
  transform: translateY(-1px);
  box-shadow: 0 8px 26px rgba(212, 180, 120, 0.32);
  filter: brightness(1.06);
}

/* 抖音唤端入口 */
.nav-douyin {
  display: inline-flex !important;
  align-items: center;
  gap: 5px;
  color: var(--text-2);
}
.nav-douyin svg { flex-shrink: 0; opacity: 0.85; transition: opacity 0.22s, transform 0.22s; }
.nav-douyin:hover { color: #4ec3ff !important; }
.nav-douyin:hover svg { opacity: 1; transform: translateY(-1px); }
.nav-douyin:hover::after { background: linear-gradient(90deg, #2b8fd4, #4ec3ff); }

/* 移动端菜单按钮 */
.nav-toggle {
  display: none;
  width: 40px; height: 40px;
  border: 1px solid var(--border-2);
  border-radius: var(--r-sm);
  background: transparent;
  cursor: pointer;
  padding: 0;
  position: relative;
}
.nav-toggle span {
  position: absolute;
  left: 11px; right: 11px;
  height: 1.5px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.3s var(--ease), opacity 0.2s;
}
.nav-toggle span:nth-child(1) { top: 14px; }
.nav-toggle span:nth-child(2) { top: 19.5px; }
.nav-toggle span:nth-child(3) { top: 25px; }
.nav-toggle.open span:nth-child(1) { transform: translateY(5.5px) rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: translateY(-5.5px) rotate(-45deg); }

@media (max-width: 960px) {
  .nav-toggle { display: block; }
  .nav-links {
    position: fixed;
    top: var(--nav-h); left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
    padding: 16px var(--pad) 26px;
    background: rgba(8, 9, 11, 0.97);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-2);
    transform: translateY(-12px);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.28s, transform 0.28s var(--ease);
    max-height: calc(100vh - var(--nav-h));
    overflow-y: auto;
  }
  .nav-links.open { opacity: 1; transform: none; pointer-events: auto; }
  .nav-links a { padding: 13px 4px; font-size: 15px; border-bottom: 1px solid var(--border); border-radius: 0; }
  .nav-links a::after { display: none; }
  .nav-cta { margin: 14px 0 0; text-align: center; border-radius: var(--r-sm); }
}

/* ── 4. 页脚 ─────────────────────────────────────────── */
.footer {
  position: relative;
  z-index: 1;
  border-top: 1px solid var(--border);
  background: linear-gradient(180deg, transparent, rgba(0, 0, 0, 0.32));
}

.footer-inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: 60px var(--pad) 34px;
}

.footer-top {
  display: grid;
  grid-template-columns: 1.6fr repeat(3, 1fr);
  gap: 44px;
  padding-bottom: 40px;
  border-bottom: 1px solid var(--border);
}

.footer-brand .nav-logo { margin-bottom: 16px; }
.footer-brand p {
  font-size: 13.5px;
  color: var(--text-3);
  line-height: 1.85;
  max-width: 320px;
}

.footer-col h4 {
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--gold);
  margin-bottom: 16px;
}
.footer-col ul { list-style: none; display: flex; flex-direction: column; gap: 10px; }
.footer-col a {
  font-size: 13.5px;
  color: var(--text-2);
  transition: color 0.2s, padding-left 0.2s;
  display: inline-block;
}
.footer-col a:hover { color: var(--gold); padding-left: 4px; }

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  flex-wrap: wrap;
  gap: 14px 24px;
  padding-top: 26px;
  border-top: 1px solid var(--border);
}

.footer-meta { display: flex; flex-direction: column; gap: 9px; }

.footer-copy { font-size: 12.5px; color: var(--text-3); }

/* 备案号：ICP 链接工信部查询系统，公安备案链接公安网 */
.footer-beian {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  font-size: 12.5px;
}
.footer-beian a {
  color: var(--text-3);
  transition: color 0.2s;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.footer-beian a:hover { color: var(--gold); }
.footer-beian img { height: 15px; width: auto; display: block; }

.footer-links { display: flex; gap: 22px; list-style: none; flex-wrap: wrap; }
.footer-links a {
  font-size: 12.5px;
  color: var(--text-3);
  transition: color 0.2s;
}
.footer-links a:hover { color: var(--gold); }

@media (max-width: 900px) {
  .footer-top { grid-template-columns: 1fr 1fr; gap: 32px; }
  .footer-brand { grid-column: 1 / -1; }
}
@media (max-width: 560px) {
  .footer-top { grid-template-columns: 1fr; }
  .footer-bottom { flex-direction: column; align-items: flex-start; }
  .footer-beian { font-size: 12px; gap: 10px; }
}

/* ── 5. 按钮 ─────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 13px 30px;
  border-radius: var(--r-pill);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.06em;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform 0.24s var(--ease), background 0.24s, border-color 0.24s,
              box-shadow 0.24s, color 0.24s;
  white-space: nowrap;
}

.btn-primary {
  background: linear-gradient(135deg, var(--gold-2), var(--gold));
  color: #17130a;
  box-shadow: 0 6px 24px rgba(212, 180, 120, 0.22);
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 34px rgba(212, 180, 120, 0.34);
}

.btn-ghost {
  border-color: var(--border-2);
  color: var(--text-2);
  background: rgba(255, 255, 255, 0.02);
}
.btn-ghost:hover {
  border-color: var(--gold);
  color: var(--gold);
  transform: translateY(-2px);
  background: var(--gold-soft);
}

.btn-cyan {
  border-color: rgba(79, 209, 197, 0.35);
  color: var(--cyan);
  background: var(--cyan-soft);
}
.btn-cyan:hover {
  background: rgba(79, 209, 197, 0.2);
  border-color: var(--cyan);
  transform: translateY(-2px);
}

.btn .arrow { transition: transform 0.24s var(--ease); }
.btn:hover .arrow { transform: translateX(4px); }

/* ── 6. 区块标题 ─────────────────────────────────────── */
.section {
  position: relative;
  z-index: 1;
  padding: clamp(64px, 9vw, 116px) var(--pad);
}

.section-inner {
  max-width: var(--max);
  margin: 0 auto;
}

.section-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 32px;
  margin-bottom: 48px;
}

.section-tag {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--gold);
  margin-bottom: 14px;
}
.section-tag::before {
  content: '';
  width: 26px;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--gold));
}

.section-title {
  font-size: clamp(28px, 4.2vw, 46px);
  font-weight: 600;
  letter-spacing: -0.015em;
  line-height: 1.2;
}
.section-title em {
  font-style: normal;
  background: linear-gradient(120deg, var(--gold-2), var(--gold) 60%, var(--gold-3));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.section-desc {
  font-size: 15px;
  color: var(--text-2);
  line-height: 1.85;
  max-width: 520px;
  margin-top: 14px;
}

/* 序号标记 */
.section-index {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--text-3);
  border: 1px solid var(--border);
  border-radius: var(--r-sm);
  padding: 6px 12px;
  flex-shrink: 0;
}

/* ── 7. 卡片通用 ─────────────────────────────────────── */
.card {
  position: relative;
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  overflow: hidden;
  transition: transform 0.32s var(--ease), border-color 0.32s, box-shadow 0.32s;
}
.card:hover {
  transform: translateY(-4px);
  border-color: var(--border-gold);
  box-shadow: var(--sh-3);
}

/* 顶部描边高光 */
.card::before {
  content: '';
  position: absolute;
  top: 0; left: 20px; right: 20px;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(212, 180, 120, 0.5), transparent);
  opacity: 0;
  transition: opacity 0.32s;
}
.card:hover::before { opacity: 1; }

/* ── 8. 标签 / 徽章 ─────────────────────────────────── */
.pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 11px;
  border-radius: var(--r-pill);
  border: 1px solid var(--gold-line);
  background: var(--gold-soft);
  color: var(--gold);
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  white-space: nowrap;
}
.pill.cyan {
  border-color: rgba(79, 209, 197, 0.34);
  background: var(--cyan-soft);
  color: var(--cyan);
}

.badge {
  position: absolute;
  top: 16px; left: 16px;
  z-index: 2;
  background: linear-gradient(135deg, var(--gold-2), var(--gold));
  color: #17130a;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.1em;
  padding: 5px 11px;
  border-radius: var(--r-pill);
  box-shadow: 0 3px 14px rgba(0, 0, 0, 0.4);
}
.badge.blue {
  background: linear-gradient(135deg, var(--cyan-2), var(--cyan));
  color: #062420;
}

/* ── 9. 表单 ─────────────────────────────────────────── */
.form-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
}

.form-group { display: flex; flex-direction: column; gap: 8px; }
.form-group.full { grid-column: 1 / -1; }

.form-label {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-3);
}
.form-label em {
  font-style: normal;
  color: var(--text-3);
  letter-spacing: 0;
  text-transform: none;
  font-size: 11px;
}

.form-input, .form-select, .form-textarea {
  background: var(--bg);
  border: 1px solid var(--border-2);
  border-radius: var(--r);
  padding: 13px 16px;
  color: var(--text);
  font-size: 14.5px;
  outline: none;
  transition: border-color 0.22s, box-shadow 0.22s, background 0.22s;
  width: 100%;
}
.form-input::placeholder, .form-textarea::placeholder { color: var(--text-3); }
.form-input:focus, .form-select:focus, .form-textarea:focus {
  border-color: var(--gold);
  background: var(--bg-1);
  box-shadow: 0 0 0 3px rgba(212, 180, 120, 0.11);
}
.form-select option { background: var(--bg-1); color: var(--text); }
.form-textarea { resize: vertical; min-height: 108px; line-height: 1.7; }

.form-submit {
  grid-column: 1 / -1;
  background: linear-gradient(135deg, var(--gold-2), var(--gold));
  color: #17130a;
  border: none;
  padding: 15px;
  font-size: 14.5px;
  font-weight: 700;
  letter-spacing: 0.1em;
  cursor: pointer;
  border-radius: var(--r);
  transition: transform 0.22s var(--ease), box-shadow 0.22s, filter 0.22s;
}
.form-submit:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 30px rgba(212, 180, 120, 0.3);
  filter: brightness(1.05);
}

@media (max-width: 720px) {
  .form-grid { grid-template-columns: 1fr; }
}

/* ── 10. 弹窗 ────────────────────────────────────────── */
.modal-overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 200;
  background: rgba(4, 5, 6, 0.86);
  backdrop-filter: blur(8px);
  align-items: center;
  justify-content: center;
  padding: 20px;
}
.modal-overlay.active { display: flex; animation: fadeIn 0.26s var(--ease); }

@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes popIn {
  from { opacity: 0; transform: translateY(14px) scale(0.97); }
  to   { opacity: 1; transform: none; }
}

.modal {
  background: var(--bg-1);
  border: 1px solid var(--border-2);
  border-radius: var(--r-xl);
  padding: 38px 40px 40px;
  max-width: 430px;
  width: 100%;
  text-align: center;
  box-shadow: var(--sh-3);
  animation: popIn 0.32s var(--ease);
}
.modal-title { font-size: 21px; font-weight: 600; margin-bottom: 10px; }
.modal-desc { font-size: 13.5px; color: var(--text-2); line-height: 1.8; margin-bottom: 24px; }

.pay-tabs {
  display: flex;
  margin-bottom: 24px;
  border: 1px solid var(--border-2);
  border-radius: var(--r);
  overflow: hidden;
}
.pay-tab {
  flex: 1;
  padding: 11px 0;
  background: transparent;
  border: none;
  color: var(--text-2);
  font-size: 14px;
  cursor: pointer;
  letter-spacing: 0.06em;
  transition: background 0.22s, color 0.22s;
}
.pay-tab + .pay-tab { border-left: 1px solid var(--border-2); }
.pay-tab.active {
  background: linear-gradient(135deg, var(--gold-2), var(--gold));
  color: #17130a;
  font-weight: 600;
}

.modal-qr-img {
  width: 200px; height: 200px;
  margin: 0 auto 20px;
  border-radius: var(--r);
  overflow: hidden;
  background: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
}
.modal-qr-img img { width: 100%; height: 100%; object-fit: cover; }

.modal-amount {
  font-family: var(--mono);
  font-size: 34px;
  font-weight: 700;
  color: var(--gold);
  margin-bottom: 6px;
}
.modal-amount-label { font-size: 13px; color: var(--text-2); margin-bottom: 24px; }

.modal-close {
  background: transparent;
  border: 1px solid var(--border-2);
  color: var(--text-2);
  padding: 11px 26px;
  cursor: pointer;
  font-size: 13.5px;
  border-radius: var(--r);
  transition: border-color 0.22s, color 0.22s, background 0.22s;
}
.modal-close:hover { border-color: var(--gold); color: var(--gold); background: var(--gold-soft); }

/* ── 11. 工具类 ──────────────────────────────────────── */
.divider { height: 1px; background: var(--border); border: 0; }

.gold-text { color: var(--gold); }
.cyan-text { color: var(--cyan); }
.mono { font-family: var(--mono); }

.section-rule {
  border-top: 1px solid var(--border);
}

/* 进场动画
   安全设计：只有在 JS 明确接管后才隐藏元素。
   这样即使脚本被拦截、加载失败或爬虫不执行 JS，内容也永远可见。 */
.reveal {
  opacity: 1;
  transform: none;
  transition: opacity 0.7s var(--ease-out), transform 0.7s var(--ease-out);
}
html.js-anim .reveal {
  opacity: 0;
  transform: translateY(22px);
}
html.js-anim .reveal.in {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; }
}