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

:root {
  --bg: #fafafa;
  --bg-elevated: #ffffff;
  --text: #1a1a1a;
  --text-muted: #5c5c5c;
  --accent: #0d9488;
  --accent-hover: #0f766e;
  --border: #e5e5e5;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04), 0 2px 8px rgba(0, 0, 0, 0.05);
  --shadow: 0 2px 4px rgba(0, 0, 0, 0.04), 0 8px 28px rgba(0, 0, 0, 0.08);
  --shadow-hover: 0 8px 32px rgba(13, 148, 136, 0.15);
  --nav-bg: rgba(250, 250, 250, 0.85);
  --wave: rgba(13, 148, 136, 0.12);
  --radius: 12px;
  --radius-lg: 16px;
  --radius-card: 16px;
  --font-sans: 'DM Sans', system-ui, sans-serif;
  --font-zh: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', system-ui, sans-serif;
  --font-display: var(--font-sans);
  --max-width: 1120px;
  --section-gap: 7rem;
  --transition: 0.3s ease;
}

[data-theme='dark'] {
  --bg: #0f0f0f;
  --bg-elevated: #1a1a1a;
  --text: #f0f0f0;
  --text-muted: #a3a3a3;
  --accent: #2dd4bf;
  --accent-hover: #5eead4;
  --border: #2a2a2a;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.25), 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow: 0 2px 4px rgba(0, 0, 0, 0.3), 0 8px 28px rgba(0, 0, 0, 0.4);
  --shadow-hover: 0 8px 32px rgba(45, 212, 191, 0.12);
  --nav-bg: rgba(15, 15, 15, 0.88);
  --wave: rgba(45, 212, 191, 0.08);
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

img,
video,
svg {
  display: block;
  max-width: 100%;
}

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

a:hover {
  color: var(--accent-hover);
}

ul {
  list-style: none;
}

.container {
  width: min(100% - 2rem, var(--max-width));
  margin-inline: auto;
}

.section-title {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 700;
  margin-bottom: 2.5rem;
  letter-spacing: -0.02em;
}

.section-title::before {
  content: '';
  display: inline-block;
  width: 3px;
  height: 1.1em;
  background: var(--accent);
  margin-right: 0.75rem;
  border-radius: 2px;
  vertical-align: -0.1em;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}