/* ==========================================================================
   基础层 — 重置、排版、氛围背景、焦点可见性、降级动效
   ========================================================================== */

/* ---------- 重置 ---------- */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 88px;          /* 锚点滚动时避开吸顶导航 */
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: 1.7;                 /* 中文正文行高 ≥ 1.7 */
  letter-spacing: 0.01em;
  color: var(--color-text);
  background: var(--color-bg);
  min-height: 100vh;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

button,
input,
textarea,
select {
  font: inherit;
  color: inherit;
}

button {
  background: none;
  border: none;
  cursor: pointer;
}

a {
  color: inherit;
  text-decoration: none;
}

ul,
ol {
  list-style: none;
}

/* ---------- 排版 ---------- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--color-text-strong);
  line-height: 1.05;                /* 大标题行高 0.95–1.1 */
  letter-spacing: -0.02em;          /* 展示字紧字距 */
  text-wrap: balance;
}

h1 { font-size: var(--fs-h1); }
h2 { font-size: var(--fs-h2); }
h3 { font-size: var(--fs-h3); letter-spacing: -0.01em; line-height: 1.25; }
h4 { font-size: var(--fs-h4); letter-spacing: 0; line-height: 1.4; }

p {
  color: var(--color-muted);
  text-wrap: pretty;
}

/* 数字统一等宽对齐，指标不跳动 */
.mono,
.num,
data {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-feature-settings: 'tnum' 1;
}

/* 渐变强调文字 */
.text-signal {
  background: var(--gradient-signal);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: var(--color-primary);
}

.text-accent-gradient {
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: var(--color-accent);
}

/* 小标签：全站统一的编号 / 分类标记语言 */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--fs-micro);
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--color-primary);
}

.eyebrow::before {
  content: '';
  width: 24px;
  height: 1px;
  background: var(--color-primary);
  box-shadow: 0 0 8px var(--color-primary-glow);
}

.eyebrow--accent { color: var(--color-accent); }
.eyebrow--accent::before { background: var(--color-accent); box-shadow: 0 0 8px var(--color-accent-glow); }

.lede {
  font-size: var(--fs-body-lg);
  line-height: 1.75;
  max-width: 62ch;                   /* 正文行长控制 */
}

/* ---------- 布局 ---------- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--container-pad);
}

.container--wide { max-width: var(--container-wide); }

.section {
  position: relative;
  padding-block: clamp(4.5rem, 9vw, 8rem);
}

.section--tight { padding-block: clamp(3rem, 6vw, 5rem); }

.section-head {
  max-width: 68ch;
  margin-bottom: clamp(2.5rem, 5vw, 4rem);
}

.section-head--center {
  margin-inline: auto;
  text-align: center;
}

.section-head--center .eyebrow { justify-content: center; }
.section-head--center .lede { margin-inline: auto; }

.section-head h2 { margin-block: var(--space-4) var(--space-5); }

.grid { display: grid; gap: var(--space-5); }
.grid-2 { grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(290px, 1fr)); }
.grid-4 { grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }

.stack { display: flex; flex-direction: column; }
.cluster { display: flex; flex-wrap: wrap; align-items: center; }

/* ---------- 氛围层：网格地平线 + 渐变辉光 + 扫描线 + 颗粒 ---------- */
.atmosphere {
  position: fixed;
  inset: 0;
  z-index: -2;
  pointer-events: none;
  background:
    radial-gradient(58rem 40rem at 8% -8%, rgba(34, 211, 238, 0.13), transparent 62%),
    radial-gradient(46rem 36rem at 96% 4%, rgba(99, 102, 241, 0.12), transparent 58%),
    radial-gradient(52rem 42rem at 50% 108%, rgba(255, 122, 24, 0.07), transparent 60%),
    var(--color-bg);
}

/* 蓝图网格：科技感的基底纹理，向上淡出形成"地平线" */
.atmosphere::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(34, 211, 238, 0.055) 1px, transparent 1px),
    linear-gradient(90deg, rgba(34, 211, 238, 0.055) 1px, transparent 1px);
  background-size: 64px 64px;
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.9) 0%, rgba(0, 0, 0, 0.25) 55%, transparent 92%);
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.9) 0%, rgba(0, 0, 0, 0.25) 55%, transparent 92%);
}

/* CRT 扫描线：极低透明度，只在暗部可感 */
.atmosphere::after {
  content: '';
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(
    180deg,
    rgba(255, 255, 255, 0.016) 0px,
    rgba(255, 255, 255, 0.016) 1px,
    transparent 1px,
    transparent 3px
  );
}

/* 颗粒噪点：消除大面积渐变的塑料感 */
.grain {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  opacity: 0.05;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%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");
}

/* 区块顶部发丝线 + 四角装饰，建立"仪表盘"秩序感 */
.rule {
  position: relative;
  padding-top: var(--space-7);
}

.rule::before {
  content: '';
  position: absolute;
  inset-inline: 0;
  top: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--color-border-strong) 22%, var(--color-border-strong) 78%, transparent);
}

/* ---------- 焦点可见性：键盘可达 ---------- */
:focus { outline: none; }

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
  border-radius: var(--radius-xs);
}

::selection {
  background: var(--color-primary);
  color: var(--color-bg);
}

/* ---------- 滚动条 ---------- */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: var(--color-bg); }
::-webkit-scrollbar-thumb {
  background: var(--color-surface-3);
  border: 2px solid var(--color-bg);
  border-radius: var(--radius-pill);
}
::-webkit-scrollbar-thumb:hover { background: var(--color-primary-dim); }

/* ---------- 无障碍工具类 ---------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  top: -100px;
  left: var(--space-4);
  z-index: var(--z-modal);
  padding: var(--space-3) var(--space-5);
  background: var(--color-primary);
  color: var(--color-bg);
  font-weight: 700;
  border-radius: var(--radius-sm);
  transition: top var(--dur-base) var(--ease-out);
}

.skip-link:focus { top: var(--space-4); }

/* ---------- 滚动揭示 ---------- */
.reveal {
  opacity: 0;
  transform: translate3d(0, 26px, 0);
  transition:
    opacity var(--dur-slow) var(--ease-out),
    transform var(--dur-slow) var(--ease-out);
  will-change: opacity, transform;
}

.reveal.is-visible {
  opacity: 1;
  transform: none;
  will-change: auto;
}

/* 编排好的错峰入场：一次序列胜过零散微交互 */
.reveal[data-delay='1'] { transition-delay: 80ms; }
.reveal[data-delay='2'] { transition-delay: 160ms; }
.reveal[data-delay='3'] { transition-delay: 240ms; }
.reveal[data-delay='4'] { transition-delay: 320ms; }
.reveal[data-delay='5'] { transition-delay: 400ms; }

/* 注：此前此处有 @media (prefers-reduced-motion: reduce) 降级块，
   会把循环动画压到 0.001ms 并冻结 WebGL 循环。
   按需求「动效默认直接启用并持续运行」，该块已整体移除：
   地球自转、光点闪烁、跑马灯滚动现在无条件生效，
   不再受操作系统「减少动画」设置影响。 */