/* =========================
   Global Variables
========================= */
:root {
  --bg: #ffffff;
  --text: #1a1a1a;
  --muted: #5f6368;
  --accent: #0b3c49;   /* 深理性蓝绿，公共机构友好 */
  --border: #e6e6e6;
  --light: #f8f9fa;
}

/* =========================
   Reset & Base
========================= */
* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI",
               Inter, Helvetica, Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.65;
}

/* =========================
   Header & Navigation
========================= */
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 24px 64px;
  border-bottom: 1px solid var(--border);
  background: #fff;
}

header strong {
  font-size: 18px;
  letter-spacing: 0.5px;
}

nav a {
  margin-left: 28px;
  text-decoration: none;
  color: var(--text);
  font-weight: 500;
}

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

/* =========================
   Sections
========================= */
section {
  max-width: 1200px;
  margin: 0 auto;
  padding: 80px 64px;
}

section:nth-of-type(even) {
  background: var(--light);
}

/* =========================
   Typography
========================= */
h1 {
  font-size: 42px;
  font-weight: 600;
  margin-bottom: 20px;
  max-width: 900px;
}

h2 {
  font-size: 28px;
  font-weight: 600;
  margin-bottom: 16px;
}

h3 {
  font-size: 20px;
  font-weight: 600;
  margin-bottom: 8px;
}

p {
  max-width: 760px;
  color: var(--muted);
  font-size: 16px;
}

/* =========================
   Grid & Cards
========================= */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 32px;
  margin-top: 40px;
}

.card {
  background: #fff;
  border: 1px solid var(--border);
  padding: 32px;
  font-size: 15px;
}

/* =========================
   Call To Action
========================= */
.cta {
  display: inline-block;
  margin-top: 28px;
  padding: 14px 30px;
  background: var(--accent);
  color: #fff;
  text-decoration: none;
  font-weight: 600;
  letter-spacing: 0.4px;
}

.cta:hover {
  opacity: 0.9;
}

/* =========================
   Footer
========================= */
footer {
  border-top: 1px solid var(--border);
  padding: 48px 64px;
  font-size: 14px;
  color: var(--muted);
  background: #fff;
}

footer p {
  margin: 6px 0;
  max-width: none;
}