:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-green: #22c55e;
  --color-orange: #f97316;
  --color-bg: #f8fafc;
  --color-surface: #ffffff;
  --color-text: #0f172a;
  --color-muted: #64748b;
  --color-border: #e2e8f0;
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.08);
  --shadow-md: 0 8px 24px rgba(37, 99, 235, 0.12);
  --radius: 12px;
  --radius-lg: 16px;
  --max-width: 1100px;
  --header-h: 64px;
  --font: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

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

a:hover {
  text-decoration: underline;
}

h1, h2, h3, h4 {
  line-height: 1.3;
  margin: 0 0 0.5em;
}

p {
  margin: 0 0 1em;
  color: var(--color-muted);
}

ul {
  margin: 0 0 1em;
  padding-left: 1.25em;
  color: var(--color-muted);
}

.container {
  width: min(100% - 32px, var(--max-width));
  margin-inline: auto;
}

.page-main {
  min-height: calc(100vh - var(--header-h) - 280px);
  padding: 32px 0 64px;
}

.page-hero {
  padding: 48px 0 32px;
  text-align: center;
}

.page-hero h1 {
  font-size: clamp(1.75rem, 4vw, 2.25rem);
  color: var(--color-text);
}

.page-hero .lead {
  font-size: 1.05rem;
  max-width: 640px;
  margin: 12px auto 0;
}

.section {
  padding: 48px 0;
}

.section-title {
  font-size: 1.5rem;
  text-align: center;
  margin-bottom: 8px;
  color: var(--color-text);
}

.section-desc {
  text-align: center;
  max-width: 560px;
  margin: 0 auto 32px;
}

.text-center {
  text-align: center;
}

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

@media (min-width: 768px) {
  .page-main {
    padding: 48px 0 80px;
  }

  .page-hero {
    padding: 64px 0 40px;
  }
}