/* ============================================================
   base.css — 重置 / 排版 / 焦点 / 氛围层 / 入场动效
   ============================================================ */

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

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: 1.7;
  color: var(--color-text);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

/* —— 氛围层：蓝图网格 + 颗粒噪点（仅浅色区） —— */
.body-atmosphere::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background:
    linear-gradient(rgba(22, 18, 13, 0.035) 1px, transparent 1px) 0 0 / 100% 64px,
    linear-gradient(90deg, rgba(22, 18, 13, 0.035) 1px, transparent 1px) 0 0 / 64px 100%;
  mask-image: radial-gradient(120% 80% at 50% 0%, #000 30%, transparent 80%);
}
.body-atmosphere::after {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 1;
  opacity: 0.05;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* —— 排版基础 —— */
h1, h2, h3, h4 { margin: 0; font-family: var(--font-display); color: var(--color-ink); }
p { margin: 0; }
a { color: inherit; text-decoration: none; }

.font-tech { font-family: var(--font-tech); letter-spacing: 0.06em; }
.muted { color: var(--color-muted); }

/* 强调色文字 */
.accent { color: var(--color-accent-ink); }
.dark .accent,
.dark-accent { color: var(--color-accent); }

/* —— 焦点可见（可访问性） —— */
:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

/* —— 跳转锚点偏移（被固定导航遮挡） —— */
section[id] { scroll-margin-top: calc(var(--nav-h) + 16px); }

/* —— 入场动画（编排一次，错峰） —— */
.reveal {
  opacity: 0;
  transform: translateY(26px);
  transition: opacity var(--dur-base) var(--ease-out),
              transform var(--dur-base) var(--ease-out);
  transition-delay: var(--reveal-delay, 0ms);
  will-change: opacity, transform;
}
.reveal.in { opacity: 1; transform: none; }

/* 首屏编排：错峰 60–120ms */
.hero-stagger > * { opacity: 0; transform: translateY(28px); }
.hero-stagger.in > * {
  opacity: 1; transform: none;
  transition: opacity var(--dur-slow) var(--ease-out),
              transform var(--dur-slow) var(--ease-out);
}
.hero-stagger.in > *:nth-child(1) { transition-delay: 60ms; }
.hero-stagger.in > *:nth-child(2) { transition-delay: 150ms; }
.hero-stagger.in > *:nth-child(3) { transition-delay: 240ms; }
.hero-stagger.in > *:nth-child(4) { transition-delay: 330ms; }
.hero-stagger.in > *:nth-child(5) { transition-delay: 420ms; }
.hero-stagger.in > *:nth-child(6) { transition-delay: 510ms; }

/* —— 降级：尊重 prefers-reduced-motion —— */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal, .hero-stagger > * { opacity: 1 !important; transform: none !important; transition: none !important; }
  * { animation: none !important; }
}

/* —— 容器 —— */
.wrap { width: 100%; max-width: var(--maxw); margin-inline: auto; padding-inline: clamp(20px, 5vw, 48px); position: relative; z-index: 2; }

/* —— 通用区块间距 —— */
.section { padding-block: var(--space-8); position: relative; }
.section.tight { padding-block: var(--space-7); }

/* —— 通用标签（eyebrow） —— */
.eyebrow {
  display: inline-flex; align-items: center; gap: 10px;
  font-family: var(--font-tech);
  font-size: var(--fs-eyebrow);
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--color-accent-ink);
  margin-bottom: var(--space-3);
}
.eyebrow::before {
  content: ""; width: 26px; height: 2px; background: var(--color-accent);
  display: inline-block;
}
.dark .eyebrow { color: var(--color-accent); }