/* ============================================================
 * Base — Reset + 全局排版 + 背景层
 * ============================================================ */
*, *::before, *::after { box-sizing: border-box; }

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

html {
  font-size: var(--fs-base);
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--f-body);
  color: var(--c-text-0);
  background: var(--c-bg-0);
  line-height: 1.6;
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
}

/* 全局背景层：网格 + 扫描线 + 辉光球 */
body::before {
  content: "";
  position: fixed; inset: 0;
  pointer-events: none;
  z-index: 0;
  background:
    radial-gradient(circle at 80% -10%, rgba(177, 75, 255, 0.18) 0%, transparent 45%),
    radial-gradient(circle at 10% 110%, rgba(0, 229, 255, 0.16) 0%, transparent 50%),
    radial-gradient(circle at 50% 50%, rgba(11, 14, 26, 0.4) 0%, var(--c-bg-0) 80%);
}
body::after {
  content: "";
  position: fixed; inset: 0;
  pointer-events: none;
  z-index: 0;
  background-image:
    linear-gradient(rgba(26, 34, 56, 0.5) 1px, transparent 1px),
    linear-gradient(90deg, rgba(26, 34, 56, 0.5) 1px, transparent 1px);
  background-size: 56px 56px;
  background-position: -1px -1px;
  mask-image: radial-gradient(ellipse at center, black 30%, transparent 80%);
  -webkit-mask-image: radial-gradient(ellipse at center, black 30%, transparent 80%);
  opacity: 0.6;
}

/* 顶部扫描线 */
.scanline {
  position: fixed; top: 0; left: 0; right: 0; height: 2px;
  z-index: 100;
  background: var(--g-mask);
  animation: scan 7s linear infinite;
  pointer-events: none;
}
@keyframes scan {
  0%   { transform: translateY(0);    opacity: 0; }
  8%   { opacity: 1; }
  92%  { opacity: 1; }
  100% { transform: translateY(100vh); opacity: 0; }
}

/* 链接 */
a { color: var(--c-cyan); text-decoration: none; transition: color var(--t-fast); }
a:hover { color: #fff; }

/* 排版 */
h1, h2, h3, h4, h5, h6 { font-family: var(--f-display); font-weight: 700; line-height: 1.15; margin: 0; letter-spacing: 0.02em; }
h1 { font-size: var(--fs-3xl); }
h2 { font-size: var(--fs-2xl); }
h3 { font-size: var(--fs-xl); }
h4 { font-size: var(--fs-lg); }
p { margin: 0 0 var(--sp-4); }

code, pre, kbd { font-family: var(--f-mono); font-size: 0.92em; }
code {
  background: rgba(0, 229, 255, 0.08);
  border: 1px solid var(--c-line-soft);
  padding: 1px 6px;
  border-radius: var(--r-xs);
  color: var(--c-cyan);
}

::selection { background: var(--c-cyan); color: var(--c-bg-0); }

/* 滚动条 */
::-webkit-scrollbar { width: 8px; height: 8px; }
::-webkit-scrollbar-track { background: var(--c-bg-0); }
::-webkit-scrollbar-thumb { background: var(--c-line); border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: var(--c-cyan); }

/* 容器 */
.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 var(--sp-5);
  position: relative;
  z-index: 1;
}

/* 通用工具 */
.mono { font-family: var(--f-mono); }
.num  { font-family: var(--f-num); font-variant-numeric: tabular-nums; }
.muted { color: var(--c-text-1); }
.dim   { color: var(--c-text-2); }
.glow  { text-shadow: var(--glow-cyan); }
.upper { text-transform: uppercase; letter-spacing: 0.12em; }

.label {
  display: inline-block;
  font-family: var(--f-mono);
  font-size: var(--fs-xs);
  text-transform: uppercase;
  letter-spacing: 0.16em;
  color: var(--c-cyan);
  padding: 4px 10px;
  border: 1px solid var(--c-line-soft);
  background: var(--c-cyan-soft);
  border-radius: var(--r-xs);
  position: relative;
}
.label::before {
  content: "//";
  margin-right: 6px;
  color: var(--c-text-2);
}

/* 通用段标题 */
.section-head {
  display: flex; align-items: baseline; gap: var(--sp-4);
  margin-bottom: var(--sp-6);
}
.section-head .tag {
  font-family: var(--f-mono);
  font-size: var(--fs-xs);
  color: var(--c-text-2);
  letter-spacing: 0.18em;
  text-transform: uppercase;
}
.section-head h2 {
  font-size: var(--fs-xl);
  color: var(--c-text-0);
}
.section-head .line {
  flex: 1; height: 1px;
  background: linear-gradient(90deg, var(--c-line-soft) 0%, transparent 100%);
}

/* 通用 enter 动画 */
@keyframes fade-up {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}
.fade-up { animation: fade-up 0.8s cubic-bezier(0.2, 0.8, 0.2, 1) backwards; }
.delay-1 { animation-delay: 0.08s; }
.delay-2 { animation-delay: 0.16s; }
.delay-3 { animation-delay: 0.24s; }
.delay-4 { animation-delay: 0.32s; }
.delay-5 { animation-delay: 0.40s; }
.delay-6 { animation-delay: 0.48s; }