/* foundation.css — 基础重置与设计变量 */
:root {
  --brand: #229ed9;
  --brand-dark: #1b86b8;
  --brand-soft: #eaf6fc;
  --ink: #101828;
  --ink-2: #1f2937;
  --muted: #5b6675;
  --line: #e5e7eb;
  --bg: #ffffff;
  --bg-soft: #f6f9fc;
  --footer-bg: #0e1a24;
  --radius-btn: 10px;
  --radius-card: 16px;
  --radius-icon: 12px;
  --container: 1200px;
  --nav-h: 68px;
  --section-y: 64px;
  --shadow-sm: 0 1px 2px rgba(16, 24, 40, .06);
  --shadow-md: 0 12px 32px rgba(16, 24, 40, .10);
  --font: system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 12px);
}

body {
  margin: 0;
  font-family: var(--font);
  font-size: 1rem;
  line-height: 1.7;
  color: var(--ink-2);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
h4,
p,
figure,
ul,
ol {
  margin: 0;
}

ul,
ol {
  padding: 0;
  list-style: none;
}

h1,
h2,
h3 {
  color: var(--ink);
  line-height: 1.28;
  font-weight: 700;
  letter-spacing: -.01em;
}

h1 {
  font-size: 2rem;
}

h2 {
  font-size: 1.5rem;
}

h3 {
  font-size: 1.125rem;
  font-weight: 600;
}

p {
  color: var(--muted);
}

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

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

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

img {
  height: auto;
}

button {
  font: inherit;
  color: inherit;
}

.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: 20px;
}

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

@media (min-width: 768px) {
  h1 {
    font-size: clamp(2rem, 4vw, 3rem);
  }

  h2 {
    font-size: 1.75rem;
  }

  :root {
    --section-y: 88px;
  }
}

@media (min-width: 1024px) {
  :root {
    --section-y: 104px;
  }
}