/* ==========================================================================
   必威品牌 · 共享站点样式 /assets/site.css
   设计依据：深夜机场导航屏 —— 墨蓝基底 / 荧光青滑行道 / 暖金编号
   ========================================================================== */

/* 1. 变量 ---------------------------------------------------------------- */
:root {
  --ink: #0B1B2B;
  --ink-2: #12283D;
  --ink-3: #0E2134;
  --deep: #050A10;
  --cyan: #38E8C6;
  --gold: #F2B84B;
  --paper: #F6F1E7;
  --stone: #9AAAB5;
  --haze: #B8C7CE;
  --moss: #5F7A5A;
  --clay: #C46B4A;

  --line: rgba(154, 170, 181, 0.2);
  --line-strong: rgba(154, 170, 181, 0.4);
  --line-cyan: rgba(56, 232, 198, 0.42);

  --font-sans: "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Source Han Sans SC", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  --font-mono: ui-monospace, "SFMono-Regular", "JetBrains Mono", "Roboto Mono", Menlo, Consolas, "Liberation Mono", monospace;

  --wrap: 1180px;
  --header-h: 72px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --t: 180ms;
}

/* 2. Reset -------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--ink);
  color: var(--haze);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  margin: 0;
  font-weight: 400;
  line-height: 1.25;
  letter-spacing: 0.04em;
  color: var(--paper);
}

p { margin: 0 0 1em; }
p:last-child { margin-bottom: 0; }

a { color: inherit; }

ul, ol { margin: 0; padding: 0; list-style: none; }

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

button { font: inherit; color: inherit; }

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

::selection { background: var(--cyan); color: var(--deep); }

#main-content { padding-top: var(--header-h); }

/* 3. 通用容器与工具 ------------------------------------------------------ */
.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 24px;
}

.skip-link {
  position: absolute;
  left: 16px;
  top: -120px;
  z-index: 120;
  padding: 10px 18px;
  background: var(--cyan);
  color: var(--deep);
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.08em;
  text-decoration: none;
  border-radius: 2px;
  transition: top var(--t) var(--ease);
}
.skip-link:focus { top: 12px; }

.bw-rule {
  height: 1px;
  border: 0;
  margin: 0;
  background: linear-gradient(90deg, var(--line-strong), transparent 78%);
}

.bw-link {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(56, 232, 198, 0.35);
  padding-bottom: 1px;
  transition: border-color var(--t) var(--ease), color var(--t) var(--ease);
}
.bw-link:hover { border-bottom-color: var(--cyan); color: var(--paper); }

/* 4. 按钮 ---------------------------------------------------------------- */
.bw-btn {
  --btn-bg: transparent;
  --btn-fg: var(--paper);
  --btn-bd: var(--line-strong);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5em;
  padding: 10px 16px;
  border: 1px solid var(--btn-bd);
  border-radius: 2px;
  background: var(--btn-bg);
  color: var(--btn-fg);
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.08em;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: background var(--t) var(--ease), color var(--t) var(--ease),
              border-color var(--t) var(--ease), transform var(--t) var(--ease),
              box-shadow var(--t) var(--ease);
}
.bw-btn:hover {
  transform: translateY(-1px);
  border-color: var(--cyan);
  color: var(--cyan);
  background: rgba(56, 232, 198, 0.08);
}
.bw-btn:active { transform: translateY(0); }

.bw-btn--cyan {
  --btn-bg: var(--cyan);
  --btn-fg: var(--deep);
  --btn-bd: var(--cyan);
}
.bw-btn--cyan:hover {
  background: #4ff2d3;
  border-color: #4ff2d3;
  color: var(--deep);
  box-shadow: 0 6px 20px rgba(56, 232, 198, 0.24);
}

.bw-btn--gold {
  --btn-bg: transparent;
  --btn-fg: var(--gold);
  --btn-bd: rgba(242, 184, 75, 0.55);
}
.bw-btn--gold:hover {
  background: rgba(242, 184, 75, 0.14);
  border-color: var(--gold);
  color: var(--gold);
}

.bw-btn--ghost {
  --btn-bg: rgba(184, 199, 206, 0.05);
  --btn-fg: var(--haze);
  --btn-bd: var(--line-strong);
}
.bw-btn--ghost:hover {
  background: rgba(184, 199, 206, 0.1);
  color: var(--paper);
  border-color: var(--haze);
}

.bw-btn--sm { padding: 7px 12px; font-size: 12px; }

/* 5. 头部 ---------------------------------------------------------------- */
.bw-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 90;
  color: var(--paper);
  background: linear-gradient(180deg, rgba(5, 10, 16, 0.9) 0%, rgba(5, 10, 16, 0.42) 62%, rgba(5, 10, 16, 0) 100%);
  border-bottom: 1px solid transparent;
  transition: background var(--t) var(--ease), border-color var(--t) var(--ease),
              box-shadow var(--t) var(--ease);
}
.bw-header[data-scrolled] {
  background: rgba(11, 27, 43, 0.96);
  border-bottom-color: var(--line);
  box-shadow: 0 14px 34px rgba(5, 10, 16, 0.5);
  backdrop-filter: blur(12px);
}

.bw-header__scan {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
  background: rgba(56, 232, 198, 0.12);
  overflow: hidden;
}
.bw-header__scan > span {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--cyan), var(--gold));
}

.bw-header__inner {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 24px;
  min-height: var(--header-h);
  display: flex;
  align-items: center;
  gap: clamp(10px, 2vw, 28px);
}

/* 品牌 */
.bw-brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  text-decoration: none;
  color: inherit;
  flex: none;
}
.bw-brand__mark {
  position: relative;
  width: 34px;
  height: 34px;
  flex: none;
  border: 1px solid var(--line-strong);
  border-radius: 2px;
  background: linear-gradient(140deg, rgba(56, 232, 198, 0.2), rgba(242, 184, 75, 0.08));
}
.bw-brand__mark i {
  position: absolute;
  left: 9px;
  height: 2px;
  background: var(--cyan);
}
.bw-brand__mark i:nth-child(1) { top: 10px; width: 16px; }
.bw-brand__mark i:nth-child(2) { top: 16px; width: 11px; background: var(--gold); }
.bw-brand__mark i:nth-child(3) { top: 22px; width: 6px; background: var(--haze); }
.bw-brand:hover .bw-brand__mark { border-color: var(--cyan); }

.bw-brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
}
.bw-brand__text strong {
  font-size: 17px;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--paper);
}
.bw-brand__sub {
  margin-top: 2px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.2em;
  color: var(--stone);
}

/* 导航 */
.bw-nav { margin-left: auto; }
.bw-nav__list {
  display: flex;
  align-items: center;
  gap: 2px;
}
.bw-nav__item { display: block; }
.bw-nav__link {
  position: relative;
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  padding: 10px 12px;
  border-radius: 2px;
  color: var(--haze);
  font-size: 14px;
  letter-spacing: 0.06em;
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--t) var(--ease), background var(--t) var(--ease);
}
.bw-nav__index {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0;
  color: var(--stone);
  transition: color var(--t) var(--ease);
}
.bw-nav__link:hover {
  color: var(--paper);
  background: rgba(56, 232, 198, 0.08);
}
.bw-nav__link:hover .bw-nav__index { color: var(--cyan); }
.bw-nav__link[aria-current="page"] { color: var(--paper); }
.bw-nav__link[aria-current="page"] .bw-nav__index { color: var(--gold); }
.bw-nav__link[aria-current="page"]::after {
  content: "";
  position: absolute;
  left: 12px;
  right: 12px;
  bottom: 3px;
  height: 2px;
  background: linear-gradient(90deg, var(--cyan), var(--gold));
}

/* 头部操作区与汉堡 */
.bw-header__actions {
  display: flex;
  align-items: center;
  gap: 8px;
  flex: none;
}

.bw-nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  flex: none;
  padding: 0;
  border: 1px solid var(--line-strong);
  border-radius: 2px;
  background: rgba(18, 40, 61, 0.7);
  color: var(--paper);
  cursor: pointer;
  transition: border-color var(--t) var(--ease), background var(--t) var(--ease);
}
.bw-nav-toggle:hover { border-color: var(--cyan); color: var(--cyan); }
.bw-nav-toggle__bars {
  position: relative;
  display: block;
  width: 18px;
  height: 12px;
  margin: 0 auto;
}
.bw-nav-toggle__bars i {
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
  background: currentColor;
  transition: transform var(--t) var(--ease), opacity var(--t) var(--ease);
}
.bw-nav-toggle__bars i:nth-child(1) { top: 0; }
.bw-nav-toggle__bars i:nth-child(2) { top: 5px; }
.bw-nav-toggle__bars i:nth-child(3) { top: 10px; }
.bw-header[data-open] .bw-nav-toggle__bars i:nth-child(1) { transform: translateY(5px) rotate(45deg); }
.bw-header[data-open] .bw-nav-toggle__bars i:nth-child(2) { opacity: 0; }
.bw-header[data-open] .bw-nav-toggle__bars i:nth-child(3) { transform: translateY(-5px) rotate(-45deg); }

/* 6. 面包屑 -------------------------------------------------------------- */
.bw-crumb {
  padding: 24px 0 0;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
}
.bw-crumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  color: var(--stone);
}
.bw-crumb__item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.bw-crumb__item + .bw-crumb__item::before {
  content: "/";
  color: rgba(154, 170, 181, 0.45);
}
.bw-crumb__link {
  color: var(--haze);
  text-decoration: none;
  transition: color var(--t) var(--ease);
}
.bw-crumb__link:hover { color: var(--cyan); }

/* 7. 章节骨架 ------------------------------------------------------------ */
.bw-section { padding: clamp(52px, 7vw, 104px) 0; }

.bw-section__head {
  display: grid;
  grid-template-columns: minmax(0, 200px) minmax(0, 1fr);
  gap: clamp(14px, 4vw, 56px);
  align-items: start;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}
.bw-num {
  font-family: var(--font-mono);
  font-size: clamp(38px, 6.4vw, 68px);
  font-weight: 300;
  line-height: 0.9;
  letter-spacing: -0.02em;
  color: rgba(242, 184, 75, 0.78);
}
.bw-eyebrow {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--cyan);
}
.bw-title {
  margin: 0 0 14px;
  font-size: clamp(28px, 3.6vw, 48px);
  font-weight: 300;
  line-height: 1.18;
  letter-spacing: 0.04em;
  text-wrap: balance;
}
.bw-lede {
  max-width: 58ch;
  margin: 0;
  font-size: 17px;
  line-height: 1.78;
  color: var(--haze);
}

/* 8. 网格与卡片 ---------------------------------------------------------- */
.bw-grid {
  display: grid;
  gap: clamp(14px, 1.6vw, 22px);
}
.bw-grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.bw-grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.bw-grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.bw-grid--index { grid-template-columns: repeat(auto-fill, minmax(224px, 1fr)); }

.bw-card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 11px;
  padding: clamp(18px, 2.1vw, 26px);
  background: linear-gradient(158deg, rgba(18, 40, 61, 0.94), rgba(11, 27, 43, 0.94));
  border: 1px solid var(--line);
  border-radius: 2px;
  box-shadow: 6px 6px 0 rgba(5, 10, 16, 0.5);
  transition: transform var(--t) var(--ease), box-shadow var(--t) var(--ease),
              border-color var(--t) var(--ease);
}
.bw-card:hover {
  transform: translate(-3px, -3px);
  border-color: var(--line-cyan);
  box-shadow: 9px 9px 0 rgba(5, 10, 16, 0.55), inset 0 0 0 1px rgba(56, 232, 198, 0.16);
}
.bw-card__label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--cyan);
}
.bw-card__title {
  margin: 0;
  font-size: 20px;
  font-weight: 400;
  line-height: 1.35;
  letter-spacing: 0.03em;
  color: var(--paper);
}
.bw-card__title a {
  text-decoration: none;
  color: inherit;
}
.bw-card__title a:hover { color: var(--cyan); }
.bw-card__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--haze);
}
.bw-card__meta {
  margin-top: auto;
  padding-top: 10px;
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--stone);
}

/* 9. 标签 / 状态 / 数据 -------------------------------------------------- */
.bw-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  border: 1px solid var(--line-strong);
  border-radius: 2px;
  background: rgba(184, 199, 206, 0.06);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--haze);
}
.bw-tag--cyan {
  color: var(--cyan);
  border-color: var(--line-cyan);
  background: rgba(56, 232, 198, 0.09);
}
.bw-tag--gold {
  color: var(--gold);
  border-color: rgba(242, 184, 75, 0.5);
  background: rgba(242, 184, 75, 0.1);
}
.bw-tag--clay {
  color: #E8996F;
  border-color: rgba(196, 107, 74, 0.55);
  background: rgba(196, 107, 74, 0.14);
}
.bw-tag--moss {
  color: #9DBE95;
  border-color: rgba(95, 122, 90, 0.65);
  background: rgba(95, 122, 90, 0.18);
}

.bw-stat {
  padding: 14px 0 14px 16px;
  border-left: 2px solid var(--cyan);
  background: linear-gradient(90deg, rgba(56, 232, 198, 0.07), transparent 72%);
}
.bw-stat--gold {
  border-left-color: var(--gold);
  background: linear-gradient(90deg, rgba(242, 184, 75, 0.08), transparent 72%);
}
.bw-stat__value {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(20px, 2.4vw, 28px);
  font-weight: 400;
  line-height: 1.2;
  letter-spacing: 0.01em;
  color: var(--paper);
}
.bw-stat__key {
  display: block;
  margin-top: 4px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--stone);
}

/* 10. 图片容器（页面阶段放置图片） -------------------------------------- */
.bw-media {
  position: relative;
  display: block;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 2px;
  aspect-ratio: 16 / 9;
  background:
    linear-gradient(118deg, transparent 42%, rgba(56, 232, 198, 0.16) 50%, transparent 58%),
    linear-gradient(150deg, #16324C 0%, #0B1B2B 55%, #050A10 100%);
}
.bw-media > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 420ms var(--ease);
}
.bw-media:hover > img { transform: scale(1.03); }
.bw-media::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: repeating-linear-gradient(0deg, rgba(184, 199, 206, 0.05) 0 1px, transparent 1px 4px);
}
.bw-media__caption {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  padding: 12px 14px 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--haze);
  background: linear-gradient(180deg, transparent, rgba(5, 10, 16, 0.88));
}
.bw-media--wide { aspect-ratio: 21 / 9; }
.bw-media--tall { aspect-ratio: 3 / 4; }
.bw-media--square { aspect-ratio: 1 / 1; }

/* 11. 正文 -------------------------------------------------------------- */
.bw-prose {
  max-width: 68ch;
  color: var(--haze);
  font-size: 16.5px;
  line-height: 1.85;
}
.bw-prose > * + * { margin-top: 1.05em; }
.bw-prose h2 {
  margin-top: 1.9em;
  padding-top: 0.9em;
  border-top: 1px solid var(--line);
  font-size: clamp(22px, 2.6vw, 30px);
  font-weight: 400;
}
.bw-prose h2:first-child {
  margin-top: 0;
  padding-top: 0;
  border-top: 0;
}
.bw-prose h3 {
  margin-top: 1.6em;
  font-size: 19px;
  font-weight: 500;
}
.bw-prose strong { color: var(--paper); font-weight: 500; }
.bw-prose a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(56, 232, 198, 0.4);
}
.bw-prose a:hover { border-bottom-color: var(--cyan); }
.bw-prose ul li {
  position: relative;
  padding-left: 20px;
}
.bw-prose ul li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.78em;
  width: 9px;
  height: 1px;
  background: var(--gold);
}
.bw-prose ol { counter-reset: bw-item; }
.bw-prose ol li {
  position: relative;
  padding-left: 34px;
  counter-increment: bw-item;
}
.bw-prose ol li::before {
  content: counter(bw-item, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 0.1em;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--gold);
}

/* 12. 折叠面板 ----------------------------------------------------------- */
.bw-panel { border-bottom: 1px solid var(--line); }
.bw-panel:first-of-type { border-top: 1px solid var(--line); }
.bw-panel__trigger {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  width: 100%;
  padding: 20px 0;
  background: none;
  border: 0;
  color: var(--paper);
  font-size: 17px;
  letter-spacing: 0.02em;
  text-align: left;
  cursor: pointer;
  transition: color var(--t) var(--ease);
}
.bw-panel__trigger:hover { color: var(--cyan); }
.bw-panel__icon {
  position: relative;
  flex: none;
  width: 14px;
  height: 14px;
  color: currentColor;
}
.bw-panel__icon::before,
.bw-panel__icon::after {
  content: "";
  position: absolute;
  background: currentColor;
  transition: transform var(--t) var(--ease), opacity var(--t) var(--ease);
}
.bw-panel__icon::before { left: 0; right: 0; top: 6px; height: 1px; }
.bw-panel__icon::after { top: 0; bottom: 0; left: 6px; width: 1px; }
.bw-panel[data-open] .bw-panel__icon::after { transform: scaleY(0); opacity: 0; }
.bw-panel__body {
  display: none;
  max-width: 72ch;
  padding: 0 0 22px;
  font-size: 15.5px;
  line-height: 1.82;
  color: var(--haze);
}
.bw-panel[data-open] .bw-panel__body { display: block; }

/* 13. 标签页 ------------------------------------------------------------- */
.bw-tabs__list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 0 0 24px;
  padding: 0 0 14px;
  border-bottom: 1px solid var(--line);
}
.bw-tab {
  appearance: none;
  padding: 8px 14px;
  border: 1px solid transparent;
  border-radius: 2px;
  background: transparent;
  color: var(--stone);
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.12em;
  cursor: pointer;
  transition: color var(--t) var(--ease), background var(--t) var(--ease),
              border-color var(--t) var(--ease);
}
.bw-tab:hover {
  color: var(--paper);
  background: rgba(56, 232, 198, 0.07);
}
.bw-tab[aria-selected="true"] {
  color: var(--deep);
  background: var(--cyan);
  border-color: var(--cyan);
  font-weight: 500;
}
.bw-tabpanel[hidden] { display: none; }

/* 14. 渐显 --------------------------------------------------------------- */
.bw-reveal { opacity: 1; }
.has-js .bw-reveal {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 420ms var(--ease), transform 420ms var(--ease);
}
.has-js .bw-reveal[data-in] {
  opacity: 1;
  transform: none;
}

/* 15. 页脚 --------------------------------------------------------------- */
.bw-footer {
  position: relative;
  overflow: hidden;
  margin-top: clamp(64px, 8vw, 110px);
  border-top: 1px solid var(--line);
  background: linear-gradient(180deg, #0D2035 0%, #050A10 78%);
  color: var(--haze);
  font-size: 14px;
}
.bw-footer::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  height: 1px;
  background: linear-gradient(90deg, var(--cyan), var(--gold) 42%, transparent 88%);
  opacity: 0.7;
}
.bw-footer::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: repeating-linear-gradient(90deg, rgba(154, 170, 181, 0.055) 0 1px, transparent 1px 88px);
}
.bw-footer > .wrap {
  position: relative;
  z-index: 1;
}

.bw-footer__lead {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 24px;
  padding: clamp(38px, 5vw, 64px) 0 clamp(28px, 3vw, 42px);
  border-bottom: 1px solid var(--line);
}
.bw-footer__eyebrow {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.22em;
  color: var(--cyan);
}
.bw-footer__claim {
  margin: 0;
  max-width: 40ch;
  font-size: clamp(19px, 2.4vw, 26px);
  font-weight: 300;
  line-height: 1.45;
  letter-spacing: 0.02em;
  color: var(--paper);
}

.bw-footer__grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: clamp(24px, 3vw, 44px);
  padding: clamp(32px, 4vw, 50px) 0;
}
.bw-footer__title {
  margin: 0 0 14px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 400;
  letter-spacing: 0.18em;
  color: var(--stone);
}
.bw-footer__list { display: flex; flex-direction: column; }
.bw-footer__list > li { padding: 0; }
.bw-footer__link {
  display: inline-block;
  padding: 6px 0;
  color: var(--haze);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--t) var(--ease), transform var(--t) var(--ease),
              border-color var(--t) var(--ease);
}
.bw-footer__link:hover {
  color: var(--cyan);
  border-bottom-color: var(--line-cyan);
  transform: translateX(3px);
}
.bw-footer__list--plain > li {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 6px 0;
}
.bw-footer__k {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--stone);
}
.bw-footer__v {
  font-size: 14.5px;
  line-height: 1.55;
  letter-spacing: 0.01em;
  color: var(--paper);
  overflow-wrap: break-word;
  word-break: break-word;
}

.bw-footer__meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 24px;
  padding: 22px 0 30px;
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--stone);
}
.bw-footer__meta p { margin: 0; }
.bw-footer__icp { color: var(--haze); }
.bw-footer__note { color: rgba(154, 170, 181, 0.7); }

/* 返回顶部 */
.bw-to-top {
  position: fixed;
  right: 20px;
  bottom: 20px;
  z-index: 70;
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  padding: 0;
  border: 1px solid var(--line-strong);
  border-radius: 2px;
  background: rgba(11, 27, 43, 0.94);
  color: var(--cyan);
  font-size: 16px;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity var(--t) var(--ease), visibility var(--t) var(--ease),
              transform var(--t) var(--ease), border-color var(--t) var(--ease);
}
.bw-to-top[data-visible] {
  opacity: 1;
  visibility: visible;
  transform: none;
}
.bw-to-top:hover { border-color: var(--cyan); }

/* 16. 响应式 ------------------------------------------------------------- */
@media (max-width: 1080px) {
  .bw-nav__link { padding: 10px 9px; font-size: 13.5px; }
  .bw-grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .bw-footer__grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 960px) {
  .bw-header {
    background: rgba(8, 20, 33, 0.97);
    border-bottom-color: var(--line);
    backdrop-filter: blur(12px);
  }
  .bw-header__inner {
    flex-wrap: wrap;
    min-height: var(--header-h);
    padding: 0 18px;
    gap: 0;
  }
  .bw-brand { margin-right: auto; }
  .bw-nav-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    order: 2;
  }
  .bw-nav {
    order: 3;
    flex: 1 0 100%;
    display: none;
    margin: 0;
    padding: 4px 0 8px;
  }
  .bw-header[data-open] .bw-nav { display: block; }
  .bw-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }
  .bw-nav__link {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 14px 2px;
    font-size: 16px;
    border-bottom: 1px solid var(--line);
    border-radius: 0;
  }
  .bw-nav__link:hover {
    background: transparent;
    color: var(--cyan);
  }
  .bw-nav__link[aria-current="page"] { color: var(--cyan); }
  .bw-nav__link[aria-current="page"]::after { display: none; }
  .bw-header__actions {
    order: 4;
    flex: 1 0 100%;
    display: none;
    gap: 10px;
    padding: 4px 0 20px;
  }
  .bw-header[data-open] .bw-header__actions { display: flex; }
  .bw-header__actions .bw-btn { flex: 1 1 auto; }

  .bw-section__head { grid-template-columns: minmax(0, 1fr); }
  .bw-num { font-size: clamp(34px, 11vw, 54px); }
  .bw-grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 640px) {
  :root { --header-h: 64px; }
  .wrap { padding: 0 18px; }
  .bw-grid--2,
  .bw-grid--3,
  .bw-grid--4,
  .bw-grid--index { grid-template-columns: minmax(0, 1fr); }
  .bw-footer__grid { grid-template-columns: minmax(0, 1fr); }
  .bw-footer__lead { align-items: flex-start; }
  .bw-footer__lead .bw-btn { width: 100%; }
  .bw-footer__meta { flex-direction: column; align-items: flex-start; }
  .bw-prose { font-size: 16px; }
  .bw-to-top { right: 14px; bottom: 14px; }
}

/* 17. 减弱动效 ----------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
  .has-js .bw-reveal { opacity: 1; transform: none; }
  .bw-media:hover > img { transform: none; }
  .bw-card:hover { transform: none; }
}