/* ============================================================
   拼图大师 · 官网样式
   设计参考 Apple 官网：大留白、SF 字体、克制的配色、柔和的阴影
   ============================================================ */

:root {
  --bg: #ffffff;
  --bg-alt: #f5f5f7;
  --text: #1d1d1f;
  --text-secondary: #6e6e73;
  --text-tertiary: #86868b;
  --accent: #0071e3;
  --accent-hover: #0077ed;
  --border: #d2d2d7;
  --card: #ffffff;
  --radius: 18px;
  --radius-sm: 12px;
  --shadow: 0 4px 16px rgba(0, 0, 0, 0.06);
  --shadow-hover: 0 12px 32px rgba(0, 0, 0, 0.1);
  --max-width: 1080px;
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text",
    "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
    sans-serif;
}

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

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  line-height: 1.5;
  letter-spacing: -0.01em;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* ---------- 顶部导航 ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.72);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

.nav__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav__brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 15px;
  font-weight: 500;
  color: var(--text);
}

.nav__brand:hover {
  text-decoration: none;
}

.nav__logo {
  width: 22px;
  height: 22px;
  border-radius: 5px;
}

.nav__links {
  display: flex;
  gap: 28px;
}

.nav__links a {
  font-size: 13px;
  color: var(--text);
  opacity: 0.85;
  transition: opacity 0.2s;
}

.nav__links a:hover {
  opacity: 1;
  text-decoration: none;
}

/* ---------- Hero ---------- */
.hero {
  text-align: center;
  padding: 80px 24px 96px;
  background: linear-gradient(180deg, #fbfbfd 0%, #ffffff 100%);
}

.hero__content {
  max-width: 720px;
  margin: 0 auto;
}

.hero__icon {
  width: 120px;
  height: 120px;
  border-radius: 26px;
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.12);
  margin-bottom: 28px;
}

.hero__title {
  font-size: 56px;
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.05;
  background: linear-gradient(135deg, #1d1d1f 0%, #424245 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero__tagline {
  margin-top: 12px;
  font-size: 24px;
  font-weight: 400;
  color: var(--text-secondary);
  letter-spacing: -0.01em;
}

.hero__meta {
  margin-top: 18px;
  font-size: 14px;
  color: var(--text-tertiary);
}

.hero__meta .dot {
  margin: 0 8px;
}

.hero__cta {
  margin-top: 36px;
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

.hero__hint {
  margin-top: 20px;
  font-size: 13px;
  color: var(--text-tertiary);
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 26px;
  border-radius: 980px;
  font-size: 16px;
  font-weight: 400;
  border: none;
  cursor: pointer;
  transition: all 0.2s ease;
  text-decoration: none;
  line-height: 1.2;
}

.btn:hover {
  text-decoration: none;
}

.btn--primary {
  background: var(--accent);
  color: #fff;
}

.btn--primary:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
}

.btn--ghost {
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
}

.btn--ghost:hover {
  background: var(--accent);
  color: #fff;
}

.btn--block {
  width: 100%;
  justify-content: center;
}

.btn--disabled {
  background: #d2d2d7;
  color: #86868b;
  cursor: not-allowed;
  pointer-events: none;
}

.btn--disabled:hover {
  transform: none;
  background: #d2d2d7;
}

/* ---------- 通用区块 ---------- */
.section {
  padding: 96px 24px;
  max-width: var(--max-width);
  margin: 0 auto;
}

.section--alt {
  max-width: none;
  background: var(--bg-alt);
}

.section--alt > * {
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
}

.section__head {
  text-align: center;
  margin-bottom: 56px;
}

.section__title {
  font-size: 40px;
  font-weight: 600;
  letter-spacing: -0.02em;
  line-height: 1.1;
}

.section__sub {
  margin-top: 12px;
  font-size: 19px;
  color: var(--text-secondary);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

/* ---------- 功能特性 ---------- */
.features {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature {
  background: var(--bg-alt);
  border-radius: var(--radius);
  padding: 36px 32px;
  text-align: center;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.feature:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.feature__icon {
  width: 64px;
  height: 64px;
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 20px;
  color: #fff;
}

.feature__icon--blue {
  background: linear-gradient(135deg, #4facfe 0%, #0071e3 100%);
}

.feature__icon--purple {
  background: linear-gradient(135deg, #a78bfa 0%, #7c3aed 100%);
}

.feature__icon--green {
  background: linear-gradient(135deg, #6ee7b7 0%, #059669 100%);
}

.feature h3 {
  font-size: 22px;
  font-weight: 600;
  margin-bottom: 8px;
}

.feature p {
  font-size: 15px;
  color: var(--text-secondary);
  line-height: 1.6;
}

.highlights {
  list-style: none;
  margin-top: 56px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.highlights li {
  text-align: center;
  padding: 0 16px;
}

.highlights strong {
  display: block;
  font-size: 19px;
  font-weight: 600;
  margin-bottom: 6px;
}

.highlights span {
  font-size: 14px;
  color: var(--text-secondary);
}

/* ---------- 下载平台卡片 ---------- */
.platforms {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.platform {
  background: var(--card);
  border-radius: var(--radius);
  padding: 36px 32px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  text-align: center;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.platform:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.platform--coming {
  opacity: 0.85;
}

.platform__logo {
  width: 56px;
  height: 56px;
  margin: 0 auto 16px;
  color: var(--text);
}

.platform__name {
  font-size: 24px;
  font-weight: 600;
}

.platform__subtitle {
  font-size: 14px;
  color: var(--text-tertiary);
  margin-top: 4px;
  min-height: 20px;
}

.platform__specs {
  margin: 24px 0;
  display: grid;
  gap: 10px;
  font-size: 14px;
}

.platform__specs div {
  display: flex;
  justify-content: space-between;
  color: var(--text-secondary);
}

.platform__specs dt {
  color: var(--text-tertiary);
}

.platform__specs dd {
  color: var(--text);
  font-weight: 500;
}

.platform__note {
  font-size: 13px;
  color: var(--text-tertiary);
  line-height: 1.6;
  margin: 20px 0 0;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}

.platform__badge {
  display: inline-block;
  margin: 4px auto 0;
  padding: 4px 12px;
  font-size: 12px;
  font-weight: 500;
  color: var(--text-secondary);
  background: var(--bg-alt);
  border-radius: 980px;
}

/* ---------- FAQ ---------- */
.faq {
  max-width: 760px;
  margin: 0 auto;
}

.faq details {
  border-bottom: 1px solid var(--border);
  padding: 20px 0;
}

.faq summary {
  font-size: 18px;
  font-weight: 500;
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--text);
}

.faq summary::-webkit-details-marker {
  display: none;
}

.faq summary::after {
  content: "+";
  font-size: 24px;
  font-weight: 300;
  color: var(--text-tertiary);
  transition: transform 0.2s;
}

.faq details[open] summary::after {
  transform: rotate(45deg);
}

.faq p {
  margin-top: 14px;
  font-size: 15px;
  color: var(--text-secondary);
  line-height: 1.7;
}

.faq code {
  background: var(--bg-alt);
  padding: 2px 8px;
  border-radius: 6px;
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 13px;
  color: var(--text);
}

/* ---------- 页脚 ---------- */
.footer {
  background: var(--bg-alt);
  border-top: 1px solid var(--border);
  padding: 32px 24px;
  color: var(--text-tertiary);
  font-size: 12px;
}

.footer__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  text-align: center;
}

.footer__note {
  margin-top: 6px;
}

/* ---------- 响应式 ---------- */
@media (max-width: 820px) {
  .hero {
    padding: 56px 24px 64px;
  }

  .hero__title {
    font-size: 40px;
  }

  .hero__tagline {
    font-size: 20px;
  }

  .section {
    padding: 64px 20px;
  }

  .section__title {
    font-size: 30px;
  }

  .section__sub {
    font-size: 17px;
  }

  .features,
  .platforms,
  .highlights {
    grid-template-columns: 1fr;
  }

  .nav__links {
    gap: 18px;
  }

  .nav__links a {
    font-size: 12px;
  }
}

@media (max-width: 480px) {
  .hero__icon {
    width: 96px;
    height: 96px;
    border-radius: 22px;
  }

  .hero__title {
    font-size: 34px;
  }

  .btn {
    padding: 11px 22px;
    font-size: 15px;
  }
}