/* ==========================================================================
   万利 · K歌与音频娱乐AI大模型平台
   全站样式表 / static/css/style.css
   设计方向：Audio AI Studio + K歌录音棚 + Generative Audio Lab
   ========================================================================== */

:root {
  /* 主色板 */
  --c-bg: #faf8f4;                 /* 暖白 */
  --c-bg-alt: #f2efe7;
  --c-night: #10142b;              /* 深夜蓝 */
  --c-night-soft: #171c3a;
  --c-night-line: #262c52;
  --c-purple: #6c5ce7;             /* 音频紫 */
  --c-purple-deep: #4b3fb8;
  --c-cyan: #35c6c1;               /* 波形青 */
  --c-cyan-soft: #bdeeec;
  --c-coral: #ff7a59;              /* 珊瑚橙点缀 */
  --c-ink: #1c2033;
  --c-ink-soft: #4b4f66;
  --c-line: #e4e0d6;
  --c-card: #ffffff;
  --c-warn-bg: #fff4ea;
  --c-warn-line: #f0d3ae;

  --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei",
    "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;

  --radius-s: 8px;
  --radius-m: 14px;
  --radius-l: 22px;
  --shadow-card: 0 12px 32px rgba(16, 20, 43, 0.08);
  --shadow-deep: 0 20px 48px rgba(16, 20, 43, 0.22);
  --maxw: 1180px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--c-bg);
  color: var(--c-ink);
  font-family: var(--font-sans);
  line-height: 1.75;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul, ol { padding-left: 1.2em; }
h1, h2, h3, h4 { line-height: 1.35; margin: 0 0 .6em; font-weight: 700; }
p { margin: 0 0 1em; }
.container { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }
section { position: relative; }
.visually-hidden {
  position: absolute; width: 1px; height: 1px; margin: -1px; overflow: hidden;
  clip: rect(0,0,0,0); white-space: nowrap; border: 0; padding: 0;
}
.skip-link {
  position: absolute; left: 12px; top: -60px; background: var(--c-night);
  color: #fff; padding: 10px 16px; border-radius: var(--radius-s); z-index: 999;
  transition: top .2s ease;
}
.skip-link:focus { top: 12px; }

/* ---------------- 顶部导航 ---------------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(250, 248, 244, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--c-line);
}
.site-header .container {
  display: flex; align-items: center; justify-content: space-between;
  height: 72px;
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 20px; color: var(--c-night); }
.brand img { width: 34px; height: 34px; }
.brand .brand-sub { font-size: 12px; font-weight: 500; color: var(--c-ink-soft); display: block; }
.brand-text { display: flex; flex-direction: column; line-height: 1.2; }

.main-nav { display: flex; gap: 4px; }
.main-nav a {
  padding: 9px 14px; border-radius: 999px; font-size: 14.5px; color: var(--c-ink-soft);
  transition: all .18s ease; white-space: nowrap;
}
.main-nav a:hover, .main-nav a[aria-current="page"] {
  background: var(--c-night); color: #fff;
}
.nav-toggle {
  display: none; width: 42px; height: 42px; border-radius: var(--radius-s);
  border: 1px solid var(--c-line); background: #fff; cursor: pointer;
  align-items: center; justify-content: center;
}
.nav-toggle span, .nav-toggle span::before, .nav-toggle span::after {
  content: ""; display: block; width: 20px; height: 2px; background: var(--c-night);
  position: relative; transition: all .2s ease;
}
.nav-toggle span::before { position: absolute; top: -6px; }
.nav-toggle span::after { position: absolute; top: 6px; }

/* ---------------- Hero ---------------- */
.hero {
  background: radial-gradient(1200px 600px at 80% -10%, rgba(108,92,231,.16), transparent 60%),
    linear-gradient(180deg, var(--c-night) 0%, var(--c-night-soft) 100%);
  color: #fff;
  padding: 72px 0 88px;
  overflow: hidden;
}
.hero .container { display: grid; grid-template-columns: 1.1fr .9fr; gap: 48px; align-items: center; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px; font-size: 13px;
  color: var(--c-cyan-soft); background: rgba(53,198,193,.12);
  border: 1px solid rgba(53,198,193,.35); padding: 6px 14px; border-radius: 999px;
  margin-bottom: 18px;
}
.hero h1 { font-size: 40px; letter-spacing: -.01em; }
.hero .lead { color: #cfd2e8; font-size: 16.5px; max-width: 560px; }
.hero-actions { display: flex; gap: 14px; margin-top: 26px; flex-wrap: wrap; }
.btn {
  display: inline-flex; align-items: center; gap: 8px; padding: 12px 22px;
  border-radius: 999px; font-size: 15px; font-weight: 600; cursor: pointer;
  border: 1px solid transparent; transition: transform .15s ease, box-shadow .15s ease;
}
.btn:hover { transform: translateY(-1px); }
.btn-primary { background: linear-gradient(120deg, var(--c-purple), var(--c-cyan)); color: #fff; box-shadow: 0 10px 24px rgba(108,92,231,.35); }
.btn-ghost { background: transparent; border-color: rgba(255,255,255,.35); color: #fff; }
.btn-dark { background: var(--c-night); color: #fff; }
.btn-dark:hover { background: var(--c-purple-deep); }
.hero-stats { display: flex; gap: 28px; margin-top: 34px; flex-wrap: wrap; }
.hero-stats div { font-size: 13px; color: #a9adc8; }
.hero-stats strong { display: block; font-size: 20px; color: #fff; font-weight: 700; }
.hero-art { position: relative; }
.hero-art img { filter: drop-shadow(0 24px 40px rgba(0,0,0,.35)); }

/* ---------------- 通用 section ---------------- */
.section { padding: 76px 0; }
.section-alt { background: var(--c-bg-alt); }
.section-head { max-width: 760px; margin: 0 auto 44px; text-align: center; }
.section-head.left { text-align: left; margin-left: 0; }
.section-kicker {
  font-size: 13px; font-weight: 700; letter-spacing: .06em; color: var(--c-purple-deep);
  text-transform: uppercase; margin-bottom: 10px; display: block;
}
.section h2 { font-size: 30px; color: var(--c-night); }
.section .desc { color: var(--c-ink-soft); font-size: 15.5px; }

/* ---------------- 工作流 / 功能卡片 ---------------- */
.grid { display: grid; gap: 20px; }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.feature-card {
  background: var(--c-card); border: 1px solid var(--c-line); border-radius: var(--radius-m);
  padding: 26px; box-shadow: var(--shadow-card);
}
.feature-card .ic { width: 44px; height: 44px; margin-bottom: 14px; }
.feature-card h3 { font-size: 17px; color: var(--c-night); }
.feature-card p { font-size: 14px; color: var(--c-ink-soft); margin-bottom: 0; }
.feature-card a.more { font-size: 13.5px; color: var(--c-purple-deep); font-weight: 600; display: inline-block; margin-top: 10px; }

/* ---------------- 文章 ---------------- */
.article {
  background: var(--c-card); border: 1px solid var(--c-line); border-radius: var(--radius-l);
  padding: 40px; margin-bottom: 28px; box-shadow: var(--shadow-card);
}
.article-meta {
  display: flex; gap: 12px; align-items: center; font-size: 13px; color: var(--c-ink-soft);
  margin-bottom: 14px; flex-wrap: wrap;
}
.tag {
  background: var(--c-bg-alt); border: 1px solid var(--c-line); border-radius: 999px;
  padding: 3px 12px; font-size: 12.5px; color: var(--c-purple-deep); font-weight: 600;
}
.article h2 { font-size: 24px; color: var(--c-night); }
.article h2.q { font-size: 22px; line-height: 1.5; }
.article .lead-p {
  font-size: 16.5px; color: var(--c-ink); border-left: 3px solid var(--c-cyan);
  padding-left: 16px; margin: 18px 0; color: #33374d;
}
.article h4 { font-size: 15.5px; color: var(--c-purple-deep); margin-top: 26px; }
.article p, .article li { font-size: 15px; color: var(--c-ink-soft); }
.article figure { margin: 24px 0; }
.article figcaption { font-size: 13px; color: #8a8ea6; text-align: center; margin-top: 8px; }
.callout {
  background: var(--c-warn-bg); border: 1px solid var(--c-warn-line); border-radius: var(--radius-m);
  padding: 16px 20px; font-size: 14.5px; color: #6b4a1f; margin: 18px 0;
}
.callout strong { color: #4a3213; }
.pull-line {
  font-size: 15.5px; font-weight: 600; color: var(--c-night); background: var(--c-bg-alt);
  border-radius: var(--radius-s); padding: 12px 16px; margin: 16px 0;
}

/* ---------------- 摘要卡片（回流二级文章） ---------------- */
.digest-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.digest-card {
  background: var(--c-card); border: 1px solid var(--c-line); border-radius: var(--radius-m);
  padding: 22px; display: flex; flex-direction: column; box-shadow: var(--shadow-card);
}
.digest-card .cat { font-size: 12px; color: var(--c-cyan); font-weight: 700; letter-spacing: .03em; }
.digest-card h3 { font-size: 16px; margin: 8px 0 10px; color: var(--c-night); }
.digest-card p { font-size: 13.8px; color: var(--c-ink-soft); flex: 1; }
.digest-card a.read { font-size: 13.5px; font-weight: 700; color: var(--c-purple-deep); margin-top: 10px; }
.digest-block { margin-bottom: 46px; }
.digest-block .block-head { display: flex; align-items: baseline; justify-content: space-between; margin-bottom: 18px; flex-wrap: wrap; gap: 10px; }
.digest-block .block-head h3 { font-size: 20px; color: var(--c-night); margin: 0; }
.digest-block .block-head a { font-size: 13.5px; color: var(--c-purple-deep); font-weight: 600; }

/* ---------------- FAQ ---------------- */
.faq-list { max-width: 880px; margin: 0 auto; }
.faq-item { border-bottom: 1px solid var(--c-line); }
.faq-q {
  width: 100%; text-align: left; background: none; border: none; cursor: pointer;
  padding: 18px 0; font-size: 15.5px; font-weight: 600; color: var(--c-night);
  display: flex; justify-content: space-between; align-items: center; gap: 16px;
  font-family: var(--font-sans);
}
.faq-q .plus { font-size: 20px; color: var(--c-purple); transition: transform .2s ease; flex-shrink: 0; }
.faq-item[data-open="true"] .plus { transform: rotate(45deg); }
.faq-a { max-height: 0; overflow: hidden; transition: max-height .25s ease; font-size: 14.5px; color: var(--c-ink-soft); }
.faq-item[data-open="true"] .faq-a { max-height: 400px; }
.faq-a p { padding-bottom: 18px; margin: 0; }
.faq-cols { columns: 1; }

/* ---------------- 公司介绍 / Footer ---------------- */
.company-box {
  background: var(--c-night); color: #fff; border-radius: var(--radius-l);
  padding: 44px; display: grid; grid-template-columns: 1fr 1fr; gap: 32px; align-items: center;
}
.company-box h2 { color: #fff; font-size: 24px; }
.company-box p { color: #c7cae0; font-size: 14.5px; }
.company-meta { list-style: none; padding: 0; font-size: 13.5px; color: #a9adc8; }
.company-meta li { padding: 6px 0; border-top: 1px solid var(--c-night-line); }
.company-meta li:first-child { border-top: none; }
.company-meta span { color: #fff; font-weight: 600; margin-right: 8px; }

.site-footer { background: var(--c-night-soft); color: #c7cae0; padding: 56px 0 28px; margin-top: 40px; }
.footer-grid { display: grid; grid-template-columns: 2fr repeat(4, 1fr); gap: 28px; }
.footer-col h4 { color: #fff; font-size: 14px; margin-bottom: 14px; }
.footer-col a { display: block; font-size: 13.5px; color: #a9adc8; padding: 5px 0; }
.footer-col a:hover { color: #fff; }
.footer-bottom {
  margin-top: 40px; padding-top: 22px; border-top: 1px solid var(--c-night-line);
  font-size: 12.5px; color: #8386a3; display: flex; justify-content: space-between; flex-wrap: wrap; gap: 10px;
}
.footer-brand { display: flex; align-items: center; gap: 10px; margin-bottom: 14px; }
.footer-brand img { width: 30px; height: 30px; }
.footer-brand strong { color: #fff; font-size: 17px; }

/* ---------------- 面包屑 / 页头 ---------------- */
.page-hero {
  background: linear-gradient(180deg, var(--c-night) 0%, var(--c-night-soft) 100%);
  color: #fff; padding: 52px 0 64px;
}
.breadcrumb { font-size: 13px; color: #a9adc8; margin-bottom: 16px; }
.breadcrumb a { color: #cfd2e8; }
.breadcrumb span { margin: 0 6px; color: #6a6e8c; }
.page-hero h1 { font-size: 32px; }
.page-hero .lead { color: #cfd2e8; max-width: 640px; font-size: 15.5px; }
.page-hero .kw-row { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 18px; }
.page-hero .kw-row span {
  font-size: 12.5px; background: rgba(255,255,255,.08); border: 1px solid rgba(255,255,255,.18);
  padding: 5px 12px; border-radius: 999px; color: #e3e5f2;
}

/* ---------------- 面板 / 演示交互 ---------------- */
.demo-panel {
  background: var(--c-card); border: 1px solid var(--c-line); border-radius: var(--radius-l);
  padding: 30px; box-shadow: var(--shadow-card);
}
.demo-panel h3 { font-size: 17px; color: var(--c-night); }
.demo-controls { display: flex; align-items: center; gap: 16px; flex-wrap: wrap; margin: 16px 0; }
.demo-controls label { font-size: 13.5px; color: var(--c-ink-soft); display: flex; align-items: center; gap: 8px; }
.demo-controls input[type="range"] { width: 180px; accent-color: var(--c-purple); }
.demo-tabs { display: flex; gap: 8px; flex-wrap: wrap; }
.demo-tabs button {
  font-family: var(--font-sans); border: 1px solid var(--c-line); background: #fff;
  padding: 8px 16px; border-radius: 999px; font-size: 13.5px; cursor: pointer; color: var(--c-ink-soft);
}
.demo-tabs button[aria-selected="true"] { background: var(--c-night); color: #fff; border-color: var(--c-night); }
.demo-note { font-size: 12.5px; color: #8a8ea6; margin-top: 12px; }

/* ---------------- 步骤 / 流程列表 ---------------- */
.step-list { list-style: none; padding: 0; counter-reset: step; }
.step-list li {
  counter-increment: step; position: relative; padding: 4px 0 20px 42px; font-size: 14.5px; color: var(--c-ink-soft);
}
.step-list li::before {
  content: counter(step); position: absolute; left: 0; top: 0; width: 28px; height: 28px;
  border-radius: 50%; background: var(--c-purple); color: #fff; font-size: 13px; font-weight: 700;
  display: flex; align-items: center; justify-content: center;
}
.step-list li strong { color: var(--c-night); display: block; margin-bottom: 3px; font-size: 15px; }

/* ---------------- 表格 ---------------- */
.table-wrap { overflow-x: auto; }
table.compare { width: 100%; border-collapse: collapse; font-size: 14px; min-width: 480px; }
table.compare th, table.compare td { border: 1px solid var(--c-line); padding: 10px 14px; text-align: left; }
table.compare th { background: var(--c-bg-alt); color: var(--c-night); }
table.compare td { color: var(--c-ink-soft); }

/* ---------------- App 功能网格 ---------------- */
.app-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
.app-tile {
  background: var(--c-card); border: 1px solid var(--c-line); border-radius: var(--radius-m);
  padding: 20px; text-align: center;
}
.app-tile img { width: 40px; height: 40px; margin: 0 auto 12px; }
.app-tile h4 { font-size: 14.5px; color: var(--c-night); margin: 0 0 4px; }
.app-tile p { font-size: 12.5px; color: var(--c-ink-soft); margin: 0; }

.download-row { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.download-card {
  background: var(--c-night); color: #fff; border-radius: var(--radius-m); padding: 24px;
  display: flex; align-items: center; gap: 16px;
}
.download-card img { width: 38px; height: 38px; }
.download-card h4 { font-size: 15px; margin: 0 0 4px; color: #fff; }
.download-card p { font-size: 12.5px; color: #a9adc8; margin: 0; }

/* ---------------- 内链条 ---------------- */
.inline-links { display: flex; gap: 12px; flex-wrap: wrap; margin: 18px 0 0; }
.inline-links a {
  font-size: 13.5px; padding: 9px 16px; border: 1px solid var(--c-line); border-radius: 999px;
  color: var(--c-purple-deep); background: #fff; font-weight: 600;
}
.inline-links a:hover { background: var(--c-night); color: #fff; border-color: var(--c-night); }

/* ---------------- 返回顶部 ---------------- */
.to-top {
  position: fixed; right: 24px; bottom: 24px; width: 46px; height: 46px; border-radius: 50%;
  background: var(--c-night); color: #fff; border: none; cursor: pointer; box-shadow: var(--shadow-deep);
  display: flex; align-items: center; justify-content: center; opacity: 0; pointer-events: none;
  transition: opacity .2s ease; z-index: 90;
}
.to-top.show { opacity: 1; pointer-events: auto; }

/* ---------------- 响应式 ---------------- */
@media (max-width: 1040px) {
  .hero .container { grid-template-columns: 1fr; }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .digest-grid { grid-template-columns: repeat(2, 1fr); }
  .app-grid { grid-template-columns: repeat(2, 1fr); }
  .company-box { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: repeat(3, 1fr); }
  .download-row { grid-template-columns: 1fr; }
}
@media (max-width: 760px) {
  .main-nav { position: fixed; top: 72px; left: 0; right: 0; bottom: 0; background: var(--c-bg);
    flex-direction: column; padding: 18px 20px; gap: 4px; transform: translateX(100%);
    transition: transform .25s ease; overflow-y: auto; }
  .main-nav.open { transform: translateX(0); }
  .main-nav a { padding: 14px 16px; font-size: 16px; border-bottom: 1px solid var(--c-line); border-radius: 0; }
  .nav-toggle { display: flex; }
  .hero h1 { font-size: 28px; }
  .section h2 { font-size: 24px; }
  .grid-3, .grid-4, .grid-2 { grid-template-columns: 1fr; }
  .digest-grid { grid-template-columns: 1fr; }
  .app-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
  .article { padding: 24px; }
  .company-box { padding: 28px; }
}