/* ==========================================================================
   基础层：重置 / 排版 / 氛围 / 可访问性降级   v3
   ========================================================================== */

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: var(--fs-base);
  line-height: 1.68;
  letter-spacing: .012em;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
h1, h2, h3, h4 { margin: 0; font-weight: 900; line-height: 1.04; letter-spacing: -.02em; }
p  { margin: 0; }
ul { margin: 0; padding: 0; list-style: none; }
a  { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; }
img, svg { display: block; max-width: 100%; }

/* ---------- 自定义滚动条：黄铜细轨 ---------- */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: var(--color-bg-deep); }
::-webkit-scrollbar-thumb {
  background: linear-gradient(180deg, var(--color-accent-deep), var(--color-accent-dark));
  border: 2px solid var(--color-bg-deep);
  border-radius: 8px;
}
::-webkit-scrollbar-thumb:hover { background: linear-gradient(180deg, var(--color-accent), var(--color-accent-deep)); }

/* ---------- 氛围层：黄铜辉光 + 制图网格 + 噪点 ---------- */
.atmosphere { position: fixed; inset: 0; z-index: 0; pointer-events: none; }
.atmosphere::before {
  content: ""; position: absolute; inset: 0;
  background:
    radial-gradient(60rem 44rem at 6% -14%, rgba(240,180,41,.17), transparent 62%),
    radial-gradient(48rem 40rem at 106% 6%,  rgba(240,180,41,.075), transparent 58%),
    radial-gradient(64rem 52rem at 50% 116%, rgba(240,180,41,.055), transparent 60%);
}
.atmosphere::after {
  content: ""; position: absolute; inset: 0; opacity: .55;
  background-image:
    linear-gradient(to right,  var(--color-line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--color-line) 1px, transparent 1px);
  background-size: 92px 92px;
  mask-image: radial-gradient(122% 92% at 50% 0%, #000 18%, transparent 78%);
  -webkit-mask-image: radial-gradient(122% 92% at 50% 0%, #000 18%, transparent 78%);
}
.grain {
  position: fixed; inset: 0; z-index: 1; pointer-events: none; opacity: .05;
  mix-blend-mode: overlay;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='200' height='200'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.85' numOctaves='3'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}
/* 顶部渐隐面纱：让首屏与后续区块衔接 */
.veil {
  position: absolute; inset: 0; z-index: -1; pointer-events: none;
  background-image: var(--grad-veil);
}

/* ---------- 排版工具 ---------- */
.eyebrow {
  font-family: var(--font-mono);
  font-size: var(--fs-2xs);
  letter-spacing: .28em;
  text-transform: uppercase;
  color: var(--color-accent);
  display: inline-flex; align-items: center; gap: 10px;
}
.eyebrow::before {
  content: ""; width: 26px; height: 1px;
  background: linear-gradient(90deg, var(--color-accent), transparent);
}
.mono { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }
.lead { font-size: var(--fs-md); color: var(--color-muted); line-height: 1.74; }
.dim  { color: var(--color-muted); }

/* 黄铜金属字：用于主标题强调与关键数字 */
.brass {
  background-image: var(--grad-brass-text);
  -webkit-background-clip: text; background-clip: text;
  color: transparent;
  -webkit-text-fill-color: transparent;
  text-shadow: none;   /* 渐变字必须关掉 text-shadow，否则只剩阴影轮廓 */
}
/* 阴刻质感 */
.engrave { text-shadow: 0 1px 0 rgba(0,0,0,.65), 0 -1px 0 rgba(255,240,214,.07); }

/* 黄铜发丝分隔线 */
.rule {
  height: 1px; border: 0; margin: 0;
  background-image: var(--grad-brass-rule);
  opacity: .7;
}

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

/* ---------- 入场序列 ---------- */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition:
    opacity   var(--dur-base) var(--ease-out),
    transform var(--dur-base) var(--ease-out);
}
.reveal.is-in { opacity: 1; transform: none; }

/* ---------- 通用渐变描边（1px 黄铜边框） ---------- */
.frame { position: relative; }
.frame::before {
  content: ""; position: absolute; inset: 0; padding: 1px;
  background-image: var(--grad-brass-frame);
  -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
          mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
  -webkit-mask-composite: xor; mask-composite: exclude;
  pointer-events: none;
}

/* ---------- 指针追光 ---------- */
[data-spot] { position: relative; }
[data-spot]::after {
  content: ""; position: absolute; inset: 0; pointer-events: none;
  background: radial-gradient(320px circle at var(--mx, 50%) var(--my, 50%),
              rgba(240,180,41,.13), rgba(240,180,41,.04) 42%, transparent 68%);
  opacity: 0; transition: opacity var(--dur-base) var(--ease-out);
}
[data-spot]:hover::after { opacity: 1; }

/* ---------- 可访问性：尊重降低动效偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1 !important; transform: none !important; transition: none !important; }
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }
}

/* ---------- 选中态 ---------- */
::selection { background: var(--color-accent); color: var(--color-bg-deep); }