:root {
  --brand-color: #1f7bff;
  --bg-color: #ffffff;
  --card-bg: #f5f7fa;
  --text-primary: #121212;
  --text-secondary: #333333;
  --text-muted: #666666;
  --border-color: #e6ebf2;
}

body[data-theme="dark"] {
  --bg-color: #121212;
  --card-bg: #1e1e1e;
  --text-primary: #ffffff;
  --text-secondary: #cccccc;
  --text-muted: #999999;
  --border-color: #2a2a2a;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Microsoft YaHei", "PingFang SC", Arial, sans-serif;
  color: var(--text-primary);
  background: var(--bg-color);
  transition: background-color 0.35s ease, color 0.35s ease;
}

a {
  color: inherit;
  text-decoration: none;
}

.top-nav {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 20px;
  padding: 14px 32px;
  background: color-mix(in srgb, var(--bg-color) 92%, transparent);
  border-bottom: 1px solid var(--border-color);
  backdrop-filter: blur(8px);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
}

.brand-logo {
  width: 40px;
  height: 40px;
  border-radius: 8px;
}

.brand-name {
  font-size: 22px;
  font-weight: 700;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 20px;
}

.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  border: 1px solid var(--border-color);
  border-radius: 999px;
  background: var(--card-bg);
  color: var(--text-primary);
  padding: 0;
  cursor: pointer;
  transition: background-color 0.3s ease, border-color 0.3s ease;
}

.theme-toggle .theme-icon {
  display: block;
  flex-shrink: 0;
}

/* 日间模式：显示月亮，点击切换夜间 */
body[data-theme="light"] .theme-icon-sun {
  display: none;
}

body[data-theme="light"] .theme-icon-moon {
  display: block;
}

/* 夜间模式：显示太阳，点击切换日间 */
body[data-theme="dark"] .theme-icon-moon {
  display: none;
}

body[data-theme="dark"] .theme-icon-sun {
  display: block;
}

.anchor-nav {
  display: flex;
  align-items: center;
  gap: 16px;
  font-size: 14px;
  color: var(--text-secondary);
}

.anchor-nav a:hover {
  color: var(--brand-color);
}

main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px 24px 48px;
}

.hero {
  padding: 28px;
  border-radius: 18px;
  background: linear-gradient(120deg, var(--card-bg) 0%, color-mix(in srgb, var(--card-bg) 76%, var(--brand-color)) 100%);
}

.hero-content {
  max-width: 840px;
}

body[data-theme="dark"] .hero {
  background: linear-gradient(120deg, #1e1e1e 0%, #202c3c 100%);
}

.hero h1 {
  margin: 0 0 12px;
  line-height: 1.35;
  font-size: 34px;
}

.hero p {
  margin: 0;
  color: var(--text-secondary);
  line-height: 1.7;
}

.selling-points {
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.selling-points li {
  border-radius: 999px;
  border: 1px solid var(--border-color);
  background: var(--bg-color);
  color: var(--text-secondary);
  padding: 7px 12px;
  font-size: 13px;
}

body[data-theme="dark"] .selling-points li {
  background: #171717;
}

.feature-section {
  margin-top: 24px;
  border-radius: 16px;
  padding: 24px;
  background: var(--card-bg);
  border: 1px solid var(--border-color);
}

.feature-section h2 {
  margin: 0 0 10px;
  font-size: 26px;
}

.feature-section p {
  margin: 0 0 16px;
  line-height: 1.75;
  color: var(--text-secondary);
}

.app-download-card {
  display: flex;
  gap: 18px;
  align-items: center;
  border: 1px solid var(--border-color);
  border-radius: 14px;
  padding: 18px;
  background: color-mix(in srgb, var(--bg-color) 90%, transparent);
}

.app-icon {
  width: 56px;
  height: 56px;
  object-fit: cover;
  border-radius: 12px;
  border: 1px solid var(--border-color);
  background: var(--bg-color);
}

.app-download-info {
  flex: 1;
}

.app-download-info h3 {
  margin: 0;
  font-size: 22px;
}

.download-actions {
  margin-top: 10px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.download-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 128px;
  padding: 10px 16px;
  border-radius: 999px;
  border: 1px solid var(--border-color);
  background: var(--bg-color);
  color: var(--text-primary);
  font-size: 14px;
  transition: border-color 0.25s ease, color 0.25s ease, background-color 0.25s ease;
}

.download-btn:hover {
  border-color: var(--brand-color);
  color: var(--brand-color);
}

.download-btn.primary {
  background: var(--brand-color);
  border-color: var(--brand-color);
  color: #ffffff;
}

.download-btn.primary:hover {
  filter: brightness(1.08);
  color: #ffffff;
}

.image-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.image-grid.single {
  grid-template-columns: minmax(0, 1fr);
}

.image-card {
  margin: 0;
  border-radius: 14px;
  padding: 12px;
  border: 1px solid var(--border-color);
  background: color-mix(in srgb, var(--bg-color) 88%, transparent);
}

.image-card img {
  width: 100%;
  max-height: 560px;
  object-fit: contain;
  border-radius: 10px;
  background: var(--bg-color);
}

.image-card figcaption {
  margin-top: 8px;
  color: var(--text-muted);
  font-size: 13px;
}

.site-footer {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  border-top: 1px solid var(--border-color);
  margin-top: 20px;
  padding: 22px 24px 28px;
  text-align: center;
  color: var(--text-muted);
}

.site-footer p {
  margin: 0;
}

@media (max-width: 980px) {
  .top-nav {
    flex-wrap: wrap;
    justify-content: center;
  }

  .anchor-nav {
    flex-wrap: wrap;
    justify-content: center;
  }
}

@media (max-width: 760px) {
  .image-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .app-download-card {
    flex-direction: column;
    align-items: flex-start;
  }

  .hero h1 {
    font-size: 28px;
  }
}