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

:root {
  --color-bg: #f4f6f9;
  --color-surface: #ffffff;
  --color-text: #1a2332;
  --color-text-muted: #5c6b7f;
  --color-primary: #2563eb;
  --color-primary-light: #dbeafe;
  --color-accent-pdf: #ef4444;
  --color-accent-audio: #8b5cf6;
  --color-border: #e2e8f0;
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 4px 16px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 8px 32px rgba(15, 23, 42, 0.1);
  --radius: 12px;
  --radius-lg: 16px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  width: 100%;
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(8px);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--color-text);
  font-weight: 700;
  font-size: 1.125rem;
}

.logo-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: var(--color-primary-light);
  border-radius: 8px;
  color: var(--color-primary);
}

.logo-icon svg {
  width: 20px;
  height: 20px;
}

.nav {
  display: flex;
  gap: 24px;
}

.nav-link {
  color: var(--color-text-muted);
  text-decoration: none;
  font-size: 0.9375rem;
  transition: color 0.2s;
}

.nav-link:hover {
  color: var(--color-primary);
}

/* Hero */
.hero {
  padding: 64px 0 48px;
  text-align: center;
  background: linear-gradient(180deg, #eff6ff 0%, var(--color-bg) 100%);
}

.hero-title {
  font-size: 2.5rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
  background: linear-gradient(135deg, #1e40af 0%, #2563eb 50%, #3b82f6 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-desc {
  font-size: 1.0625rem;
  color: var(--color-text-muted);
  max-width: 480px;
  margin: 0 auto;
}

/* Section */
.section-title {
  font-size: 1.375rem;
  font-weight: 700;
  margin-bottom: 24px;
  color: var(--color-text);
}

.tools-section {
  padding: 48px 0;
}

.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.tool-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s, box-shadow 0.2s;
  position: relative;
  overflow: hidden;
}

.tool-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--card-accent, var(--color-primary)), transparent);
  opacity: 0;
  transition: opacity 0.2s;
}

.tool-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.tool-card:hover::before {
  opacity: 1;
}

.tool-card:first-child {
  --card-accent: var(--color-accent-pdf);
}

.tool-card:last-child {
  --card-accent: var(--color-accent-audio);
}

.tool-icon {
  width: 52px;
  height: 52px;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
}

.tool-icon svg {
  width: 26px;
  height: 26px;
}

.tool-icon--pdf {
  background: #fef2f2;
  color: var(--color-accent-pdf);
}

.tool-icon--audio {
  background: #f5f3ff;
  color: var(--color-accent-audio);
}

.tool-name {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.tool-desc {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  margin-bottom: 20px;
  line-height: 1.7;
}

.tool-badge {
  display: inline-block;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-primary);
  background: var(--color-primary-light);
  padding: 4px 12px;
  border-radius: 20px;
}

/* About */
.about-section {
  padding: 48px 0 64px;
}

.about-text {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  line-height: 1.8;
  max-width: 640px;
}

/* Footer */
.site-footer {
  margin-top: auto;
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: 24px 0;
  text-align: center;
}

.footer-copy {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: 6px;
}

.footer-beian a {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  text-decoration: none;
  transition: color 0.2s;
}

.footer-beian a:hover {
  color: var(--color-primary);
}

/* Responsive */
@media (max-width: 640px) {
  .hero {
    padding: 48px 0 32px;
  }

  .hero-title {
    font-size: 2rem;
  }

  .nav {
    gap: 16px;
  }

  .nav-link {
    font-size: 0.875rem;
  }

  .tool-card {
    padding: 24px 20px;
  }
}