/* 设计 token —— 镜像 App LightAppColors(见 app/.../ui/theme/Color.kt),做克制高级化 */
:root {
  --bg: #FCFCFA;          /* 极浅暖白,不用死白 */
  --bg-alt: #F4F6F3;
  --surface: #FFFFFF;
  --accent: #4CAF50;      /* App 品牌绿,点缀用 */
  --accent-deep: #2E7D5B; /* 低饱和墨绿,大面积文字/描边 */
  --text: #1A1D1A;
  --text-mute: #6B726B;
  --divider: #E8ECE8;
  --radius: 18px;
  --maxw: 1120px;
  --shadow-soft: 0 18px 48px -18px rgba(30, 60, 40, .28);
  --ease: cubic-bezier(.22, .61, .36, 1);
  --font: -apple-system, BlinkMacSystemFont, "PingFang SC", "Noto Sans SC",
          "Microsoft YaHei", "Segoe UI", Roboto, sans-serif;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font);
  color: var(--text);
  background: linear-gradient(180deg, var(--bg) 0%, var(--bg-alt) 100%);
  background-attachment: fixed;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }
.container { width: min(100% - 40px, var(--maxw)); margin-inline: auto; }
.section { padding: clamp(64px, 10vw, 128px) 0; }

/* 顶栏:玻璃拟态,滚动加阴影(.scrolled 由 JS 挂) */
.nav {
  position: sticky; top: 0; z-index: 50;
  backdrop-filter: saturate(180%) blur(16px);
  -webkit-backdrop-filter: saturate(180%) blur(16px);
  background: rgba(255, 255, 255, .68);
  border-bottom: 1px solid transparent;
  transition: border-color .3s var(--ease), box-shadow .3s var(--ease), background .3s var(--ease);
}
.nav.scrolled { border-bottom-color: var(--divider); box-shadow: 0 6px 24px -16px rgba(30,60,40,.3); background: rgba(255,255,255,.82); }
.nav__inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.brand { display: flex; align-items: center; gap: 8px; font-weight: 700; font-size: 20px; letter-spacing: .5px; color: var(--accent-deep); }
.brand__dot { width: 10px; height: 10px; border-radius: 50%; background: var(--accent); }
.nav__links { display: flex; align-items: center; gap: 28px; }
.nav__links a { color: var(--text-mute); font-size: 15px; transition: color .2s var(--ease); }
.nav__links a:hover, .nav__links a.active { color: var(--text); }

.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 12px 26px; border-radius: 999px; font-weight: 600; font-size: 15px;
  background: var(--accent); color: #fff; border: none; cursor: pointer;
  box-shadow: 0 10px 26px -10px rgba(76,175,80,.6);
  transition: transform .2s var(--ease), box-shadow .2s var(--ease), background .2s var(--ease);
}
.btn:hover { transform: translateY(-2px); box-shadow: 0 16px 34px -12px rgba(76,175,80,.7); background: #43a047; }
.btn--lg { padding: 16px 40px; font-size: 17px; }
.btn--ghost { background: transparent; color: var(--accent-deep); box-shadow: none; border: 1.5px solid var(--divider); }
.btn--ghost:hover { background: var(--surface); border-color: var(--accent); }

/* 汉堡(移动端显示) */
.nav__burger { display: none; flex-direction: column; gap: 5px; background: none; border: none; cursor: pointer; padding: 8px; }
.nav__burger span { width: 22px; height: 2px; background: var(--text); border-radius: 2px; transition: .3s var(--ease); }

.footer { padding: 56px 0 40px; border-top: 1px solid var(--divider); color: var(--text-mute); font-size: 14px; }
.footer__inner { display: flex; flex-wrap: wrap; gap: 16px; justify-content: space-between; align-items: center; }
.footer__links { display: flex; gap: 20px; }
.footer__beian { width: 100%; text-align: center; margin-top: 20px; font-size: 12px; opacity: .7; }

/* 滚动淡入(JS 加 .in) */
.reveal { opacity: 0; transform: translateY(24px); transition: opacity .6s var(--ease), transform .6s var(--ease); }
.reveal.in { opacity: 1; transform: none; }

/* 响应式 */
@media (max-width: 760px) {
  .nav__links {
    position: fixed; inset: 64px 0 auto 0; flex-direction: column; gap: 0;
    background: rgba(255,255,255,.97); backdrop-filter: blur(16px);
    padding: 8px 0; border-bottom: 1px solid var(--divider);
    transform: translateY(-120%); transition: transform .35s var(--ease); pointer-events: none;
  }
  .nav__links.open { transform: none; pointer-events: auto; }
  .nav__links a { padding: 14px 24px; width: 100%; }
  .nav__links .btn { margin: 10px 24px; }
  .nav__burger { display: flex; }
}

/* HERO */
.hero { position: relative; overflow: hidden; padding: clamp(80px, 12vw, 160px) 0 clamp(64px, 9vw, 120px); }
.hero__bg { position: absolute; inset: 0; z-index: -2; background: center/cover no-repeat; opacity: .55; }
.hero::after { /* 绿色径向柔光叠加 */
  content: ""; position: absolute; inset: 0; z-index: -1;
  background: radial-gradient(60% 50% at 70% 30%, rgba(76,175,80,.18), transparent 70%),
              linear-gradient(180deg, rgba(252,252,250,.2), var(--bg-alt) 92%);
}
.hero__inner { display: grid; grid-template-columns: 1.1fr .9fr; gap: 48px; align-items: center; }
.hero h1 { font-size: clamp(38px, 6vw, 68px); line-height: 1.08; letter-spacing: -1px; font-weight: 800; }
.hero h1 .grad { background: linear-gradient(120deg, var(--accent-deep), var(--accent)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero p.sub { margin: 24px 0 36px; font-size: clamp(16px, 2vw, 20px); color: var(--text-mute); max-width: 30ch; }
.hero__cta { display: flex; gap: 14px; flex-wrap: wrap; }
.hero__phone { justify-self: center; }
.phone {
  width: min(280px, 72vw); border-radius: 40px; background: #fff; padding: 10px;
  box-shadow: var(--shadow-soft); border: 1px solid var(--divider);
  transform: rotate(-3deg); transition: transform .5s var(--ease);
}
.phone:hover { transform: rotate(0) translateY(-6px); }
.phone img { border-radius: 32px; width: 100%; }

/* 功能区:交替左右 */
.feature { display: grid; grid-template-columns: 1fr 1fr; gap: clamp(32px, 6vw, 96px); align-items: center; }
.feature + .feature { margin-top: clamp(64px, 9vw, 120px); }
.feature:nth-child(even) .feature__media { order: -1; }
.feature__eyebrow { display: inline-block; font-size: 13px; font-weight: 700; letter-spacing: 1.5px; text-transform: uppercase; color: var(--accent); margin-bottom: 12px; }
.feature h2 { font-size: clamp(26px, 3.4vw, 40px); line-height: 1.2; letter-spacing: -.5px; font-weight: 800; }
.feature p { margin-top: 16px; font-size: 17px; color: var(--text-mute); max-width: 42ch; }
.feature__media { display: flex; justify-content: center; }
.feature .phone { transform: rotate(2.5deg); }
.feature:nth-child(even) .phone { transform: rotate(-2.5deg); }

.section__head { text-align: center; max-width: 40ch; margin: 0 auto clamp(48px, 7vw, 80px); }
.section__head h2 { font-size: clamp(28px, 4vw, 46px); font-weight: 800; letter-spacing: -.5px; }
.section__head p { margin-top: 14px; color: var(--text-mute); font-size: 18px; }

/* 底部 CTA */
.cta { text-align: center; }
.cta__card {
  background: linear-gradient(135deg, var(--accent-deep), var(--accent));
  color: #fff; border-radius: 28px; padding: clamp(48px, 7vw, 88px) 24px;
  box-shadow: var(--shadow-soft);
}
.cta__card h2 { font-size: clamp(28px, 4vw, 44px); font-weight: 800; }
.cta__card p { margin: 14px 0 32px; opacity: .92; font-size: 18px; }
.cta__card .btn { background: #fff; color: var(--accent-deep); }
.cta__card .btn:hover { background: #f3f8f3; }

@media (max-width: 760px) {
  .hero__inner, .feature { grid-template-columns: 1fr; }
  .hero__phone { margin-top: 8px; }
  .feature:nth-child(even) .feature__media { order: 0; }
  .feature__media { order: -1; }
}

/* 关于页 */
.about-hero { text-align: center; padding: clamp(88px, 12vw, 150px) 0 clamp(40px, 6vw, 72px); }
.about-hero h1 { font-size: clamp(34px, 5vw, 56px); font-weight: 800; letter-spacing: -1px; }
.about-hero p { margin-top: 18px; color: var(--text-mute); font-size: clamp(17px, 2vw, 20px); max-width: 36ch; margin-inline: auto; }
.story { max-width: 62ch; margin: 0 auto; }
.story p { font-size: 18px; color: var(--text); margin-bottom: 22px; }
.story p .em { color: var(--accent-deep); font-weight: 600; }
.values { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; margin-top: clamp(48px, 7vw, 80px); }
.value { background: var(--surface); border: 1px solid var(--divider); border-radius: var(--radius); padding: 32px 28px; box-shadow: 0 12px 30px -20px rgba(30,60,40,.25); }
.value__icon { width: 44px; height: 44px; border-radius: 12px; background: rgba(76,175,80,.12); display: flex; align-items: center; justify-content: center; font-size: 22px; margin-bottom: 16px; }
.value h3 { font-size: 20px; font-weight: 700; }
.value p { margin-top: 8px; color: var(--text-mute); font-size: 15px; }
@media (max-width: 760px) { .values { grid-template-columns: 1fr; } }

/* 双屏叠放(Hero / K歌): 后屏靠左偏上, 前屏靠右偏下, 轻微反向倾斜 */
.phone-stack { position: relative; width: min(340px, 82vw); margin-inline: auto; padding: 20px 0; }
.phone-stack .phone { position: absolute; width: 64%; margin: 0; }
.phone-stack .phone--back { top: 0; left: 0; transform: rotate(-5deg); z-index: 1; opacity: .96; }
.phone-stack .phone--front { top: 34px; right: 0; transform: rotate(4deg); z-index: 2; }
.phone-stack .phone:hover { transform: rotate(0) translateY(-6px); z-index: 3; }
/* 占位撑高(两屏绝对定位, 需给容器一个高度) */
.phone-stack::after { content: ""; display: block; padding-top: 150%; }

/* 手机底图 + 叠放大卡片(配音练习: 手机完整截图 + 右下角放大的音高/字幕块作放大镜标注) */
.phone-callout { position: relative; width: min(300px, 78vw); margin-inline: auto; padding-bottom: 40px; }
.phone-callout .phone { margin: 0; transform: rotate(-3deg); }
.callout-card {
  position: absolute; right: -14%; bottom: 0; width: 78%;
  background: #fff; padding: 8px; border-radius: 16px;
  border: 1px solid var(--divider); box-shadow: var(--shadow-soft);
  transform: rotate(2deg); transition: transform .5s var(--ease);
}
.callout-card img { border-radius: 10px; width: 100%; display: block; }
.callout-card:hover { transform: rotate(0) translateY(-4px); }

@media (max-width: 760px) {
  .phone-stack { width: min(300px, 84vw); }
  .phone-callout { width: min(260px, 72vw); }
  .callout-card { right: -6%; width: 72%; }
}