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

body {
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  background: #f5f7fa;
  color: #1f2937;
  line-height: 1.9;
  padding: 0 20px;
}

header {
  max-width: 640px;
  margin: 0 auto;
  padding: 80px 0 40px;
}

h1 {
  font-size: 36px;
  letter-spacing: 2px;
  margin-bottom: 8px;
}

.sub {
  color: #6b7280;
  font-size: 14px;
}

main { max-width: 640px; margin: 0 auto; }

section {
  margin-bottom: 40px;
  padding: 24px;
  background: #fff;
  border-radius: 12px;
}

h2 { font-size: 18px; margin-bottom: 10px; }

footer {
  max-width: 640px;
  margin: 60px auto 40px;
  color: #9ca3af;
  font-size: 13px;
}

/* 小马 —— 不，小鱼 */
#fish {
  position: fixed;
  left: 0;
  top: 0;
  font-size: 32px;
  pointer-events: none;
  will-change: transform;
}