/* ==========================================================================
   BASE — 重置 / 画布背景 / 通用排版元件
   ========================================================================== */

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

html,
body {
  margin: 0;
  padding: 0;
}

html {
  background: var(--bg-void);
  -webkit-text-size-adjust: 100%;
}

body {
  min-height: 100vh;
  color: var(--ink-1);
  font-family: var(--font-cn);
  font-size: 15px;
  line-height: 1.7;
  font-weight: 400;
  letter-spacing: 0.01em;
  background-color: var(--bg-void);
  /* 空间感：三层光晕 + 一层极淡网格，全部集中在页面上部 */
  background-image:
    radial-gradient(
      1100px 620px at 50% -8%,
      rgba(46, 80, 120, 0.55),
      transparent 62%
    ),
    radial-gradient(
      760px 460px at 6% 24%,
      rgba(34, 62, 98, 0.4),
      transparent 66%
    ),
    radial-gradient(
      820px 520px at 96% 18%,
      rgba(36, 56, 92, 0.36),
      transparent 68%
    ),
    linear-gradient(180deg, #0a1019 0%, #080d15 58%, #060910 100%);
  background-repeat: no-repeat;
  background-attachment: fixed;
  overflow-x: hidden;
}

/* 极细网格：营造"基地结构图"的底层质感，不抢内容 */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background-image:
    linear-gradient(to right, rgba(146, 178, 219, 0.05) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(146, 178, 219, 0.04) 1px, transparent 1px);
  background-size: 96px 96px, 96px 96px;
  mask-image: radial-gradient(
    130% 90% at 50% 0%,
    rgba(0, 0, 0, 0.85),
    transparent 78%
  );
}

/* 电影颗粒：极低不透明度，避免"塑料感" */
.grain {
  position: fixed;
  inset: -50%;
  pointer-events: none;
  z-index: 1;
  opacity: 0.055;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='160' height='160'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.86' numOctaves='3' stitchTiles='stitch'/></filter><rect width='160' height='160' filter='url(%23n)'/></svg>");
  mix-blend-mode: overlay;
}

main,
header.topbar,
footer.site-foot {
  position: relative;
  z-index: 2;
}

/* ---------------- 排版元件 ---------------- */

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-feature-settings: "tnum" 1;
}

/* 小标签：LABEL STYLE */
.tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 10.5px;
  font-weight: 500;
  line-height: 1;
  letter-spacing: var(--track-label);
  text-transform: uppercase;
  color: var(--ink-2);
}

/* 带短横线的小节标题 */
.sect-head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  margin-bottom: 18px;
}

.sect-head__rule {
  flex: 0 0 22px;
  height: 1px;
  background: var(--line-mid);
  transform: translateY(-4px);
}

.sect-head__cn {
  font-size: 13px;
  letter-spacing: 0.34em;
  color: var(--ink-1);
  font-weight: 400;
}

.sect-head__en {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: var(--track-label);
  color: var(--ink-3);
  text-transform: uppercase;
}

/* 细发光线（区域分隔） */
.hair {
  height: 1px;
  border: 0;
  margin: 0;
  background: linear-gradient(
    90deg,
    transparent,
    var(--line-mid) 18%,
    var(--line-mid) 82%,
    transparent
  );
}

/* ---------------- 按钮 ---------------- */

button {
  font-family: inherit;
  cursor: pointer;
  border: 0;
  background: none;
  color: inherit;
}

.ghost-btn {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-2);
  padding: 6px 12px;
  border: var(--hair) solid var(--line-mid);
  border-radius: 1px;
  transition: color 0.3s var(--ease-out), border-color 0.3s var(--ease-out),
    background-color 0.3s var(--ease-out);
}

.ghost-btn:hover {
  color: var(--ink-0);
  border-color: var(--line-hi);
  background: rgba(127, 178, 217, 0.06);
}

.ghost-btn:focus-visible,
a:focus-visible,
[tabindex]:focus-visible {
  outline: 1px solid var(--accent);
  outline-offset: 3px;
}

/* ---------------- 滚动条 ---------------- */

::-webkit-scrollbar {
  width: 9px;
  height: 9px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background: rgba(146, 178, 219, 0.16);
  border-radius: 9px;
}
::-webkit-scrollbar-thumb:hover {
  background: rgba(146, 178, 219, 0.28);
}

::selection {
  background: rgba(127, 178, 217, 0.24);
  color: #fff;
}

/* ---------------- 启动兜底提示 ---------------- */

#boot-fallback {
  position: fixed;
  inset: 0;
  z-index: 99;
  display: grid;
  place-content: center;
  gap: 10px;
  text-align: center;
  padding: 32px;
  background: var(--bg-void);
  color: var(--ink-2);
  font-size: 14px;
  letter-spacing: 0.06em;
}
#boot-fallback b {
  color: var(--accent);
  font-weight: 500;
}

.bf__box {
  max-width: 460px;
  display: grid;
  gap: 8px;
  padding: 26px clamp(20px, 4vw, 34px);
  border: var(--hair) solid var(--line-mid);
  background: rgba(8, 12, 19, 0.7);
  text-align: left;
  line-height: 1.8;
}

.bf__box strong {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--accent);
}

.bf__box p {
  margin: 0;
  font-size: 12.5px;
  color: var(--ink-2);
}

.bf__box p.mono {
  font-size: 11px;
  color: var(--ink-3);
  word-break: break-all;
}

/* ---------------- 可访问性 ---------------- */

.skip-link {
  position: absolute;
  top: -100px;
  left: var(--gutter);
  z-index: 100;
  padding: 8px 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--bg-void);
  background: var(--accent);
  text-decoration: none;
}

.skip-link:focus {
  top: 10px;
}

.noscript-note {
  position: relative;
  z-index: 2;
  margin: 0 var(--gutter);
  padding: 14px 18px;
  border: var(--hair) solid var(--line-mid);
  font-size: 13px;
  color: var(--ink-2);
}

/* ---------------- 减弱动效偏好 ---------------- */

/*
 * 系统开启「减少动态效果」时：
 * 只关掉过渡（悬停、展开这类跟随手指的动作），
 * 保留大厅扫描、刻度环、倒计时到点这些叙事性动效——
 * 它们很慢、没有大面积位移，是这个站的"在运转"感来源。
 */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition-duration: 0.001ms !important;
  }
}