/* ============================================================
   微笑社区 · 官网样式
   设计语言:Airbnb(浅色白底·圆角·留白)+ Linear(发丝线·单一强调·负字距)
   与 App 内 style.css 保持同一套 design token
   ============================================================ */

:root {
  --canvas: #f7f7f7;
  --card-bg: #ffffff;
  --ink: #222222;
  --body: #3f3f3f;
  --muted: #6a6a6a;
  --muted-soft: #929292;
  --hairline: #ebebeb;
  --hairline-strong: #dddddd;
  --accent: #333333;
  --accent-dark: #111111;
  --accent-soft: #e5e5e5;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-pill: 9999px;
  --shadow-1:
    0 0 0 1px rgba(0, 0, 0, 0.02),
    0 2px 6px rgba(0, 0, 0, 0.04),
    0 4px 8px rgba(0, 0, 0, 0.04);
  --shadow-2:
    0 2px 4px rgba(0, 0, 0, 0.03),
    0 10px 30px rgba(0, 0, 0, 0.06);
  --maxw: 1120px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'PingFang SC',
    'Helvetica Neue', 'Microsoft YaHei', 'Inter', sans-serif;
  background: var(--canvas);
  color: var(--ink);
  letter-spacing: -0.01em;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* 顶栏 */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(247, 247, 247, 0.82);
  backdrop-filter: blur(16px) saturate(1.6);
  border-bottom: 1px solid var(--hairline);
}
.nav-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  gap: 20px;
}
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--ink); }
.brand-dot {
  width: 22px; height: 22px; border-radius: 50%;
  background: radial-gradient(circle at 32% 30%, #fff, var(--accent) 70%);
  box-shadow: inset 0 0 0 1px rgba(0, 0, 0, 0.08);
}
.brand-name { font-weight: 650; font-size: 18px; letter-spacing: 0.02em; }
.nav-links { margin-left: auto; display: flex; gap: 28px; }
.nav-links a {
  text-decoration: none; color: var(--muted); font-size: 15px; transition: color 0.2s;
}
.nav-links a:hover { color: var(--ink); }
.nav-cta { margin-left: 8px; }

/* 按钮 */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 10px 20px; border-radius: var(--radius-pill);
  text-decoration: none; font-size: 15px; font-weight: 600;
  transition: transform 0.15s ease, box-shadow 0.2s ease, background 0.2s ease;
  white-space: nowrap;
}
.btn:active { transform: scale(0.97); }
.btn-primary {
  background: var(--accent); color: #fff;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.14);
}
.btn-primary:hover { background: var(--accent-dark); }
.btn-ghost {
  background: transparent; color: var(--ink);
  border: 1px solid var(--hairline-strong);
}
.btn-ghost:hover { border-color: var(--accent-soft); background: #fff; }

/* Hero */
.hero {
  max-width: var(--maxw); margin: 0 auto; padding: 88px 24px 64px;
  display: flex; justify-content: center;
}
.hero-inner {
  display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 48px; align-items: center;
  max-width: 980px;
}
.eyebrow {
  display: inline-block; font-size: 13px; font-weight: 600; letter-spacing: 0.12em;
  color: var(--muted); text-transform: uppercase; margin-bottom: 16px;
}
.hero h1 {
  font-size: clamp(40px, 6vw, 64px); line-height: 1.08; font-weight: 700;
  letter-spacing: -0.03em; margin-bottom: 20px;
}
.hero-sub { font-size: 18px; color: var(--muted); max-width: 46ch; margin-bottom: 32px; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-bottom: 18px; }
.hero-note {
  font-size: 13px; color: var(--muted-soft);
  display: inline-flex; align-items: center; gap: 6px;
}
.hero-note::before {
  content: ""; width: 7px; height: 7px; border-radius: 50%;
  background: #7ecb8f; display: inline-block;
}

/* 手机示意 */
.hero-phone { display: flex; justify-content: center; }
.phone-frame {
  width: 250px; border-radius: 36px; padding: 12px;
  background: #fff; box-shadow: var(--shadow-2), 0 24px 60px rgba(0, 0, 0, 0.08);
  border: 1px solid var(--hairline);
}
.screen-top {
  height: 22px; display: flex; align-items: center; justify-content: center;
  margin-bottom: 6px;
}
.screen-pill { width: 74px; height: 5px; border-radius: 3px; background: var(--hairline-strong); }
.screen-content {
  background: var(--canvas); border-radius: 22px; padding: 16px 12px;
  display: flex; flex-direction: column; gap: 10px; min-height: 380px;
  border: 1px solid var(--hairline);
}
.card { border-radius: 12px; background: #fff; box-shadow: var(--shadow-1); height: 60px; }
.card-a { height: 96px; margin-bottom: 4px; position: relative; overflow: hidden; }
.card-a::after {
  content: ""; position: absolute; inset: 0;
  background: linear-gradient(120deg, var(--accent-soft), transparent 60%);
  opacity: 0.6;
}
.card-b { height: 46px; }
.card-c { height: 40px; opacity: 0.85; }

/* dock */
.dock {
  margin: 12px auto 2px; width: 88%; display: flex; justify-content: space-around;
  align-items: center; padding: 8px 12px; border-radius: 24px;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.85), rgba(255, 255, 255, 0.5));
  backdrop-filter: blur(8px); border: 1px solid var(--hairline);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}
.dock-item {
  width: 34px; height: 34px; border-radius: 12px; display: grid; place-items: center;
  font-size: 17px; color: var(--muted-soft); background: transparent;
}
.dock-item.active { background: var(--accent); color: #fff; }
.dock-item .smile-key { font-style: normal; font-weight: 700; }

/* 特性 */
.features {
  background: #fff; border-top: 1px solid var(--hairline); border-bottom: 1px solid var(--hairline);
}
.section-head { max-width: var(--maxw); margin: 0 auto; padding: 96px 24px 20px; text-align: center; }
.section-head h2 { font-size: clamp(28px, 4vw, 40px); letter-spacing: -0.02em; margin-bottom: 14px; }
.section-head p { color: var(--muted); font-size: 17px; }
.feature-grid {
  max-width: var(--maxw); margin: 0 auto; padding: 44px 24px 96px;
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px;
}
.feature-card {
  background: var(--card-bg); border: 1px solid var(--hairline);
  border-radius: var(--radius-md); padding: 28px 24px; transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.feature-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-2); }
.feature-icon {
  font-size: 22px; margin-bottom: 16px; width: 46px; height: 46px;
  display: grid; place-items: center; border-radius: 14px;
  background: var(--canvas); color: var(--ink);
}
.feature-card h3 { font-size: 18px; margin-bottom: 8px; letter-spacing: -0.01em; }
.feature-card p { color: var(--muted); font-size: 14.5px; line-height: 1.65; }

/* About */
.about-inner {
  max-width: var(--maxw); margin: 0 auto; padding: 96px 24px;
  display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center;
}
.about-copy h2 { font-size: clamp(26px, 3.6vw, 38px); letter-spacing: -0.02em; margin-bottom: 18px; }
.about-copy p { color: var(--muted); font-size: 16.5px; margin-bottom: 24px; }
.about-list { list-style: none; display: flex; flex-direction: column; gap: 12px; }
.about-list li {
  position: relative; padding-left: 30px; font-size: 15.5px; color: var(--ink);
}
.about-list li::before {
  content: ""; position: absolute; left: 0; top: 6px;
  width: 16px; height: 16px; border-radius: 50%;
  background: var(--accent); opacity: 0.85;
  box-shadow: inset 0 0 0 3px #fff;
}
.about-visual { position: relative; min-height: 340px; }
.about-card {
  position: absolute; padding: 20px 24px; border-radius: var(--radius-md);
  background: #fff; box-shadow: var(--shadow-2); font-weight: 600; font-size: 16px;
  border: 1px solid var(--hairline);
}
.about-1 { top: 6%; left: 4%; transform: rotate(-3deg); }
.about-2 { top: 38%; left: 34%; transform: rotate(1deg); background: var(--accent); color: #fff; }
.about-3 { top: 66%; left: 8%; transform: rotate(2deg); }
.about-visual::before {
  content: ""; position: absolute; inset: 10% 12%; border-radius: 28px;
  background: linear-gradient(140deg, var(--accent-soft), var(--canvas));
  opacity: 0.55;
}

/* 下载 */
.download { background: #fff; border-top: 1px solid var(--hairline); }
.download-inner { max-width: var(--maxw); margin: 0 auto; padding: 96px 24px; text-align: center; }
.download h2 { font-size: clamp(28px, 4vw, 42px); letter-spacing: -0.02em; margin-bottom: 14px; }
.download-sub { color: var(--muted); font-size: 17px; margin-bottom: 40px; }
.download-cards {
  display: flex; gap: 20px; justify-content: center; flex-wrap: wrap; max-width: 640px; margin: 0 auto;
}
.dl-card {
  flex: 1 1 260px; text-decoration: none; color: var(--ink);
  border: 1px solid var(--hairline); border-radius: var(--radius-md);
  padding: 28px; text-align: left; transition: transform 0.2s ease, box-shadow 0.2s ease;
  background: var(--card-bg);
}
.dl-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-2); }
.dl-title { display: block; font-size: 18px; font-weight: 650; margin-bottom: 8px; }
.dl-sub { color: var(--muted-soft); font-size: 14px; }
.download-note { margin-top: 28px; font-size: 13px; color: var(--muted-soft); }

/* 页脚 */
.footer { border-top: 1px solid var(--hairline); }
.footer-inner {
  max-width: var(--maxw); margin: 0 auto; padding: 32px 24px;
  display: flex; justify-content: space-between; align-items: center; gap: 16px;
  color: var(--muted-soft); font-size: 14px; flex-wrap: wrap;
}
.footer-brand { color: var(--muted); font-weight: 600; }

/* ======== 响应式 ======== */
@media (max-width: 880px) {
  .hero { padding-top: 56px; }
  .hero-inner { grid-template-columns: 1fr; gap: 40px; }
  .hero-phone { order: -1; }
  .feature-grid { grid-template-columns: repeat(2, 1fr); padding-bottom: 64px; }
  .section-head { padding-top: 64px; }
  .about-inner { grid-template-columns: 1fr; gap: 40px; padding: 64px 24px; }
  .about-visual { min-height: 300px; }
  .download-inner { padding: 64px 24px; }
}

@media (max-width: 560px) {
  .nav-links { display: none; }
  .nav-cta { margin-left: auto; }
  .feature-grid { grid-template-columns: 1fr; }
  .hero { padding: 48px 20px 48px; }
  .hero-actions .btn { flex: 1 1 auto; }
  .footer-inner { justify-content: center; text-align: center; }
}