/* ==========================================================================
   博业赛场 · 共享站点样式 / assets/site.css
   夜间转播指挥台：深墨绿底屏 + 冷白数据卡 + 青柠状态线 + 电光橙提醒
   ========================================================================== */

/* ---------- 1. Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

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

body, h1, h2, h3, h4, h5, p, ul, ol, li, figure, figcaption, blockquote, dl, dd {
  margin: 0;
}

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

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

button, input, select, textarea {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
}

a { color: inherit; }

table { border-collapse: collapse; width: 100%; }

:where(a, button, summary, [tabindex]):focus-visible {
  outline: 2px solid var(--by-lime);
  outline-offset: 3px;
}

/* ---------- 2. 变量 ---------- */
:root {
  --by-ink: #061E17;
  --by-ink-2: #0B2C22;
  --by-ink-3: #04140F;
  --by-paper: #F3F7F2;
  --by-lime: #C7FF3F;
  --by-orange: #FF6C2F;
  --by-mist: #93A99E;
  --by-line: #020906;
  --by-pale: #DCE6DF;
  --by-cool: #AEBDB5;
  --by-alert: #E94B2C;

  --by-hair: rgba(147, 169, 158, 0.22);
  --by-hair-strong: rgba(147, 169, 158, 0.42);
  --by-hair-lime: rgba(199, 255, 63, 0.38);
  --by-veil: rgba(199, 255, 63, 0.10);

  --by-shell: 1320px;
  --by-gutter: clamp(16px, 4vw, 56px);
  --by-ease: cubic-bezier(0.2, 0.7, 0.3, 1);
  --by-shadow: 0 18px 44px rgba(2, 9, 6, 0.42);

  --by-font-sans: "HarmonyOS Sans SC", "Source Han Sans SC", "Noto Sans SC",
    "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", sans-serif;
  --by-font-mono: "JetBrains Mono", "IBM Plex Mono", "SFMono-Regular", ui-monospace,
    Menlo, Consolas, "Courier New", monospace;
}

/* ---------- 3. 基础排版 ---------- */
@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}

body {
  background-color: var(--by-ink);
  color: var(--by-pale);
  font-family: var(--by-font-sans);
  font-size: 16px;
  line-height: 1.8;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

@media (min-width: 768px) {
  body { font-size: 17px; }
}

::selection {
  background: var(--by-lime);
  color: var(--by-ink);
}

h1, h2, h3, h4, h5 {
  font-weight: 900;
  line-height: 1.16;
  color: var(--by-paper);
}

a { text-decoration-thickness: 1px; }

/* ---------- 4. 跳转链接 ---------- */
.by-skip {
  position: fixed;
  top: -120px;
  left: 10px;
  z-index: 400;
  display: inline-block;
  padding: 12px 18px;
  background: var(--by-lime);
  color: var(--by-ink);
  font-weight: 800;
  font-size: 14px;
  letter-spacing: 0.04em;
  text-decoration: none;
  border: 1px solid var(--by-line);
  transition: top 0.2s var(--by-ease);
}

.by-skip:focus,
.by-skip:focus-visible {
  top: 10px;
}

/* ---------- 5. 页头 ---------- */
.by-header {
  position: sticky;
  top: 0;
  z-index: 200;
  background: rgba(6, 30, 23, 0.95);
  border-bottom: 1px solid var(--by-hair);
  color: var(--by-pale);
  backdrop-filter: blur(10px) saturate(120%);
  -webkit-backdrop-filter: blur(10px) saturate(120%);
}

/* 5.1 顶部转播数据条 */
.by-header__meter {
  border-bottom: 1px solid var(--by-hair);
  background-image: linear-gradient(90deg, rgba(199, 255, 63, 0.12), rgba(6, 30, 23, 0) 58%);
}

.by-header__meterinner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding-block: 7px;
}

.by-meter__label {
  min-width: 0;
  font-family: var(--by-font-mono);
  font-size: 10px;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--by-mist);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.by-meter__status {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  flex: 0 0 auto;
  font-family: var(--by-font-mono);
  font-size: 10px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--by-lime);
}

.by-dot {
  width: 6px;
  height: 6px;
  background: var(--by-lime);
  box-shadow: 0 0 0 0 rgba(199, 255, 63, 0.55);
  animation: by-pulse 2.6s var(--by-ease) infinite;
}

@keyframes by-pulse {
  0%   { box-shadow: 0 0 0 0 rgba(199, 255, 63, 0.55); }
  60%  { box-shadow: 0 0 0 7px rgba(199, 255, 63, 0); }
  100% { box-shadow: 0 0 0 0 rgba(199, 255, 63, 0); }
}

/* 5.2 主栏：品牌 · 导航 */
.by-header__bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: clamp(16px, 3vw, 40px);
  padding-block: 13px;
}

.by-brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--by-paper);
  flex: 0 0 auto;
}

.by-brand__mark {
  position: relative;
  width: 30px;
  height: 30px;
  flex: 0 0 auto;
  background: var(--by-lime);
  clip-path: polygon(0 0, 100% 0, 100% 68%, 68% 100%, 0 100%);
  transition: background-color 0.2s var(--by-ease), transform 0.2s var(--by-ease);
}

.by-brand__mark::after {
  content: "";
  position: absolute;
  left: 6px;
  bottom: 7px;
  width: 17px;
  height: 2px;
  background: var(--by-ink);
  transform: skewX(-24deg);
}

.by-brand:hover .by-brand__mark,
.by-brand:focus-visible .by-brand__mark {
  background: var(--by-orange);
  transform: translateY(-1px);
}

.by-brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.06;
}

.by-brand__name {
  font-size: clamp(17px, 1.6vw, 20px);
  font-weight: 900;
  letter-spacing: 0.06em;
}

.by-brand__tag {
  margin-top: 4px;
  font-family: var(--by-font-mono);
  font-size: 9.5px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--by-mist);
}

/* 5.3 导航 */
.by-nav {
  display: flex;
  align-items: center;
  gap: clamp(12px, 1.8vw, 26px);
}

.by-nav__list {
  display: flex;
  align-items: center;
  gap: clamp(12px, 1.8vw, 26px);
}

.by-nav__item { position: relative; }

.by-nav__link {
  position: relative;
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  padding-block: 8px;
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--by-pale);
  text-decoration: none;
  transition: color 0.18s var(--by-ease);
}

.by-nav__link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 2px;
  height: 2px;
  background: var(--by-lime);
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform 0.24s var(--by-ease);
}

.by-nav__idx {
  font-family: var(--by-font-mono);
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.08em;
  color: var(--by-mist);
  transition: color 0.18s var(--by-ease);
}

.by-nav__label { white-space: nowrap; }

.by-nav__link:hover,
.by-nav__link:focus-visible {
  color: var(--by-lime);
}

.by-nav__link:hover::after,
.by-nav__link:focus-visible::after {
  transform: scaleX(1);
}

.by-nav__link:hover .by-nav__idx { color: var(--by-mist); }

.by-nav__link[aria-current="page"] { color: var(--by-lime); }

.by-nav__link[aria-current="page"]::after {
  transform: scaleX(1);
  background: var(--by-lime);
  box-shadow: 0 0 10px rgba(199, 255, 63, 0.45);
}

.by-nav__link[aria-current="page"] .by-nav__idx { color: var(--by-orange); }

/* 5.4 页头行动按钮 */
.by-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 18px;
  background: var(--by-lime);
  border: 1px solid var(--by-lime);
  color: var(--by-ink);
  font-size: 14px;
  font-weight: 800;
  letter-spacing: 0.04em;
  text-decoration: none;
  white-space: nowrap;
  box-shadow: 4px 4px 0 0 rgba(2, 9, 6, 0.7);
  transition: background-color 0.18s var(--by-ease), color 0.18s var(--by-ease),
    border-color 0.18s var(--by-ease), box-shadow 0.18s var(--by-ease),
    transform 0.14s var(--by-ease);
}

.by-cta:hover,
.by-cta:focus-visible {
  background: var(--by-orange);
  border-color: var(--by-orange);
  color: #140800;
  box-shadow: 4px 4px 0 0 rgba(199, 255, 63, 0.55);
}

.by-cta:active {
  transform: translate(1px, 1px);
  box-shadow: 2px 2px 0 0 rgba(199, 255, 63, 0.55);
}

/* 5.5 移动导航按钮 */
.by-navtoggle {
  display: none;
  align-items: center;
  gap: 10px;
  padding: 8px 12px;
  border: 1px solid var(--by-hair-lime);
  color: var(--by-lime);
  font-family: var(--by-font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  cursor: pointer;
  transition: background-color 0.18s var(--by-ease), border-color 0.18s var(--by-ease);
}

.by-navtoggle:hover { background: var(--by-veil); }

.by-navtoggle__bars {
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.by-navtoggle__bars i {
  display: block;
  width: 16px;
  height: 2px;
  background: currentColor;
  transition: transform 0.22s var(--by-ease), opacity 0.22s var(--by-ease);
}

.by-navtoggle[aria-expanded="true"] .by-navtoggle__bars i:nth-child(1) {
  transform: translateY(5px) rotate(45deg);
}

.by-navtoggle[aria-expanded="true"] .by-navtoggle__bars i:nth-child(2) {
  opacity: 0;
}

.by-navtoggle[aria-expanded="true"] .by-navtoggle__bars i:nth-child(3) {
  transform: translateY(-5px) rotate(-45deg);
}

/* 5.6 阅读进度条 */
.by-header__progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
  background-image: linear-gradient(90deg, var(--by-lime), var(--by-orange));
  transform: scaleX(0);
  transform-origin: 0 50%;
  will-change: transform;
}

/* ---------- 6. 页脚 ---------- */
.by-footer {
  position: relative;
  margin-top: clamp(40px, 6vw, 92px);
  background: var(--by-ink-2);
  border-top: 1px solid var(--by-hair-lime);
  color: var(--by-pale);
}

.by-footer__rule {
  height: 2px;
  background-image: linear-gradient(90deg, var(--by-lime), rgba(199, 255, 63, 0.06) 58%, var(--by-orange));
}

.by-footer__inner {
  padding-block: clamp(34px, 5vw, 68px) clamp(18px, 3vw, 28px);
}

.by-footer__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(22px, 4vw, 36px);
}

.by-footer__col { min-width: 0; }

.by-footer__sign {
  font-size: clamp(20px, 2.2vw, 26px);
  font-weight: 900;
  letter-spacing: 0.05em;
  color: var(--by-paper);
  line-height: 1.2;
}

.by-footer__tag {
  margin-top: 8px;
  font-family: var(--by-font-mono);
  font-size: 10.5px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--by-lime);
}

.by-footer__note {
  margin-top: 14px;
  max-width: 34ch;
  font-size: 13.5px;
  line-height: 1.75;
  color: var(--by-cool);
}

.by-footer__title {
  margin-bottom: 14px;
  font-family: var(--by-font-mono);
  font-size: 10.5px;
  font-weight: 500;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--by-mist);
}

.by-footer__list {
  display: flex;
  flex-direction: column;
  gap: 9px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--by-cool);
}

.by-footer__list li {
  min-width: 0;
  overflow-wrap: anywhere;
}

.by-footer__list a {
  position: relative;
  display: inline-block;
  padding-bottom: 2px;
  color: var(--by-pale);
  text-decoration: none;
  background-image: linear-gradient(var(--by-lime), var(--by-lime));
  background-repeat: no-repeat;
  background-position: 0 100%;
  background-size: 0 1px;
  transition: background-size 0.24s var(--by-ease), color 0.18s var(--by-ease);
}

.by-footer__list a:hover,
.by-footer__list a:focus-visible {
  color: var(--by-lime);
  background-size: 100% 1px;
}

.by-footer__legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 24px;
  margin-top: clamp(24px, 4vw, 44px);
  padding-top: 18px;
  border-top: 1px solid var(--by-hair);
  font-family: var(--by-font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--by-mist);
}

.by-footer__copy { color: var(--by-pale); }
.by-footer__icp { color: var(--by-mist); }
.by-footer__stamp { color: var(--by-cool); }

/* ---------- 7. 通用结构组件 ---------- */
.by-shell {
  width: 100%;
  max-width: var(--by-shell);
  margin-inline: auto;
  padding-inline: var(--by-gutter);
}

.by-section { padding-block: clamp(40px, 6vw, 88px); }
.by-section--tight { padding-block: clamp(24px, 3vw, 44px); }

.by-rule {
  height: 1px;
  border: 0;
  background: var(--by-hair);
}

/* 7.1 章节带 */
.by-band {
  background: var(--by-ink-2);
  border-top: 1px solid var(--by-hair-lime);
  border-bottom: 1px solid var(--by-hair);
}

.by-band__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px clamp(12px, 3vw, 32px);
  padding-block: clamp(16px, 2.4vw, 26px);
}

.by-band__index {
  font-family: var(--by-font-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--by-lime);
  white-space: nowrap;
}

.by-band__title {
  font-size: clamp(18px, 2vw, 24px);
  font-weight: 800;
  letter-spacing: 0.02em;
  color: var(--by-paper);
}

.by-band__meta {
  font-family: var(--by-font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--by-mist);
  margin-left: auto;
}

/* 7.2 文本层级 */
.by-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--by-font-mono);
  font-size: 11px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--by-mist);
}

.by-eyebrow::before {
  content: "";
  width: 22px;
  height: 2px;
  background: var(--by-lime);
  flex: 0 0 auto;
}

.by-title {
  font-size: clamp(28px, 4vw, 56px);
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: -0.01em;
  color: var(--by-paper);
  text-wrap: balance;
}

.by-title--slant {
  display: inline-block;
  transform: skewX(-4deg);
  transform-origin: left bottom;
}

.by-lead {
  max-width: 62ch;
  font-size: clamp(16px, 1.4vw, 19px);
  line-height: 1.85;
  color: var(--by-pale);
}

.by-prose {
  max-width: 68ch;
  color: var(--by-pale);
  line-height: 1.85;
}

.by-prose > * + * { margin-top: 1em; }
.by-prose strong { color: var(--by-paper); font-weight: 800; }
.by-prose a { color: var(--by-lime); }

.by-data {
  font-family: var(--by-font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
}

/* 7.3 网格 */
.by-grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: clamp(14px, 2vw, 28px);
}

.by-span-4 { grid-column: span 4; }
.by-span-5 { grid-column: span 5; }
.by-span-6 { grid-column: span 6; }
.by-span-7 { grid-column: span 7; }
.by-span-8 { grid-column: span 8; }
.by-span-12 { grid-column: span 12; }

/* 7.4 按钮 */
.by-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 20px;
  background: var(--by-lime);
  border: 1px solid var(--by-lime);
  color: var(--by-ink);
  font-size: 15px;
  font-weight: 800;
  letter-spacing: 0.04em;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.18s var(--by-ease), color 0.18s var(--by-ease),
    border-color 0.18s var(--by-ease), transform 0.14s var(--by-ease);
}

.by-btn:hover,
.by-btn:focus-visible {
  background: var(--by-orange);
  border-color: var(--by-orange);
  color: #140800;
}

.by-btn:active { transform: translate(1px, 1px); }

.by-btn--ghost {
  background: transparent;
  border-color: var(--by-hair-lime);
  color: var(--by-lime);
}

.by-btn--ghost:hover,
.by-btn--ghost:focus-visible {
  background: var(--by-veil);
  border-color: var(--by-lime);
  color: var(--by-lime);
}

/* 7.5 卡片 */
.by-card {
  position: relative;
  padding: clamp(18px, 2.4vw, 28px);
  background: var(--by-ink-2);
  border: 1px solid var(--by-hair);
  color: var(--by-pale);
  transition: border-color 0.2s var(--by-ease), transform 0.2s var(--by-ease),
    background-color 0.2s var(--by-ease);
}

.by-card:hover,
.by-card:focus-within {
  border-color: var(--by-lime);
  transform: translateY(-2px);
}

.by-card--paper {
  background: var(--by-paper);
  border-color: var(--by-line);
  color: var(--by-line);
}

.by-card--paper:hover,
.by-card--paper:focus-within {
  border-color: var(--by-orange);
}

.by-card--paper h2,
.by-card--paper h3,
.by-card--paper h4 { color: var(--by-line); }

/* 7.6 标签与筛选 */
.by-tag {
  display: inline-block;
  padding: 3px 8px;
  font-family: var(--by-font-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--by-lime);
  background: var(--by-veil);
  border: 1px solid var(--by-hair-lime);
  white-space: nowrap;
}

.by-tag--orange {
  color: var(--by-orange);
  background: rgba(255, 108, 47, 0.14);
  border-color: rgba(255, 108, 47, 0.42);
}

.by-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 14px;
  background: transparent;
  border: 1px solid var(--by-hair);
  color: var(--by-pale);
  font-family: var(--by-font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  cursor: pointer;
  transition: background-color 0.18s var(--by-ease), color 0.18s var(--by-ease),
    border-color 0.18s var(--by-ease);
}

.by-chip:hover,
.by-chip:focus-visible {
  border-color: var(--by-lime);
  color: var(--by-lime);
}

.by-chip[aria-pressed="true"],
.by-chip.is-active {
  background: var(--by-lime);
  border-color: var(--by-lime);
  color: var(--by-ink);
}

/* 7.7 横向轨道 */
.by-rail {
  display: flex;
  gap: clamp(12px, 1.6vw, 20px);
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  padding-bottom: 8px;
  scrollbar-width: none;
  -ms-overflow-style: none;
  cursor: grab;
  touch-action: pan-x pan-y;
}

.by-rail::-webkit-scrollbar { display: none; }

.by-rail[data-dragging="true"] {
  cursor: grabbing;
  scroll-snap-type: none;
}

.by-rail__item {
  flex: 0 0 clamp(240px, 32vw, 360px);
  scroll-snap-align: start;
  min-width: 0;
}

/* 7.8 堆叠折叠卡 */
.by-stack {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.by-stack__item {
  background: var(--by-ink-2);
  border: 1px solid var(--by-hair);
  transition: border-color 0.2s var(--by-ease), background-color 0.2s var(--by-ease);
}

.by-stack__item:hover { border-color: var(--by-hair-lime); }

.by-stack__item[data-open="true"] {
  border-color: var(--by-hair-lime);
  background-image: linear-gradient(180deg, rgba(199, 255, 63, 0.07), rgba(11, 44, 34, 0));
}

.by-stack__head {
  display: flex;
  align-items: center;
  gap: 14px;
  width: 100%;
  padding: 16px 18px;
  color: var(--by-paper);
  font-size: 16px;
  font-weight: 700;
  text-align: left;
  cursor: pointer;
}

.by-stack__num {
  flex: 0 0 auto;
  font-family: var(--by-font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.16em;
  color: var(--by-lime);
}

.by-stack__sign {
  position: relative;
  flex: 0 0 auto;
  margin-left: auto;
  width: 14px;
  height: 14px;
}

.by-stack__sign::before,
.by-stack__sign::after {
  content: "";
  position: absolute;
  background: var(--by-lime);
  transition: transform 0.22s var(--by-ease), background-color 0.2s var(--by-ease);
}

.by-stack__sign::before { left: 0; top: 6px; width: 14px; height: 2px; }
.by-stack__sign::after { left: 6px; top: 0; width: 2px; height: 14px; }

.by-stack__item[data-open="true"] .by-stack__sign::after { transform: scaleY(0); }
.by-stack__item[data-open="true"] .by-stack__sign::before { background: var(--by-orange); }

.by-stack__body {
  padding: 0 18px 18px;
  font-size: 15.5px;
  line-height: 1.85;
  color: var(--by-pale);
}

.by-stack__body[hidden] { display: none; }

/* 7.9 技能树步骤节点 */
.by-steps {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.by-steps__node {
  position: relative;
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 14px 16px;
  background: var(--by-ink-2);
  border: 1px solid var(--by-hair);
  color: var(--by-pale);
  text-align: left;
  cursor: pointer;
  transition: border-color 0.2s var(--by-ease), background-color 0.2s var(--by-ease);
}

.by-steps__node:hover { border-color: var(--by-hair-lime); }

.by-steps__node + .by-steps__node::before {
  content: "";
  position: absolute;
  left: 27px;
  top: -14px;
  width: 1px;
  height: 14px;
  background: var(--by-hair-strong);
}

.by-steps__node[aria-current="true"],
.by-steps__node.is-active {
  border-color: var(--by-lime);
  background-image: linear-gradient(90deg, rgba(199, 255, 63, 0.10), rgba(11, 44, 34, 0));
}

.by-steps__num {
  flex: 0 0 auto;
  padding-top: 3px;
  font-family: var(--by-font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--by-lime);
}

.by-steps__title {
  display: block;
  font-size: 16px;
  font-weight: 800;
  color: var(--by-paper);
}

.by-steps__text {
  display: block;
  margin-top: 4px;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--by-mist);
}

/* 7.10 图像容器基础 */
.by-media {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 10;
  border: 1px solid var(--by-hair);
  color: var(--by-mist);
  background-color: var(--by-ink-3);
  background-image:
    repeating-linear-gradient(90deg, rgba(147, 169, 158, 0.13) 0 1px, transparent 1px 64px),
    repeating-linear-gradient(0deg, rgba(147, 169, 158, 0.13) 0 1px, transparent 1px 64px),
    linear-gradient(150deg, #0B2C22 0%, #061E17 58%, #02100B 100%);
}

.by-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(0.92) contrast(1.06) brightness(0.92);
  transition: transform 0.5s var(--by-ease), filter 0.4s var(--by-ease);
}

.by-media::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image: linear-gradient(180deg, rgba(6, 30, 23, 0) 42%, rgba(6, 30, 23, 0.74) 100%);
}

.by-media--wide { aspect-ratio: 21 / 9; }
.by-media--tall { aspect-ratio: 3 / 4; }
.by-media--square { aspect-ratio: 1 / 1; }

.by-media:hover img { transform: scale(1.03); }

.by-figure {
  display: flex;
  flex-direction: column;
  gap: 10px;
  min-width: 0;
}

.by-figure__cap {
  font-family: var(--by-font-mono);
  font-size: 10.5px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--by-mist);
}

/* 7.11 面包屑 */
.by-crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-family: var(--by-font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--by-mist);
}

.by-crumbs ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.by-crumbs li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--by-cool);
}

.by-crumbs a {
  color: var(--by-pale);
  text-decoration: none;
  transition: color 0.18s var(--by-ease);
}

.by-crumbs a:hover,
.by-crumbs a:focus-visible { color: var(--by-lime); }

.by-crumbs [aria-current="page"] { color: var(--by-lime); }

/* ---------- 8. 响应式 ---------- */
@media (max-width: 1023px) {
  .by-navtoggle { display: inline-flex; }

  .by-header__bar {
    flex-wrap: wrap;
    padding-block: 12px;
    gap: 10px;
  }

  .by-nav {
    order: 3;
    flex: 1 0 100%;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    margin-top: 10px;
    padding-top: 8px;
    border-top: 1px solid var(--by-hair);
  }

  .by-nav[data-open] { display: flex; }

  .by-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    width: 100%;
  }

  .by-nav__item { border-bottom: 1px solid var(--by-hair); }

  .by-nav__link {
    display: flex;
    width: 100%;
    gap: 12px;
    padding-block: 13px;
    font-size: 16px;
  }

  .by-nav__link::after {
    left: 0;
    right: auto;
    bottom: 6px;
    width: 32px;
  }

  .by-nav__link:hover::after,
  .by-nav__link:focus-visible::after { transform: scaleX(1); }

  .by-cta {
    width: 100%;
    margin-top: 14px;
    padding-block: 13px;
  }

  .by-footer__grid { grid-template-columns: 1fr; }
}

@media (min-width: 640px) and (max-width: 1023px) {
  .by-footer__grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 639px) {
  .by-brand__tag { display: none; }
  .by-meter__label { letter-spacing: 0.14em; }
  .by-meter__status { letter-spacing: 0.12em; }
  .by-span-4, .by-span-5, .by-span-6, .by-span-7, .by-span-8 { grid-column: span 12; }
  .by-band__meta { margin-left: 0; flex: 1 0 100%; }
}

@media (max-width: 899px) {
  .by-span-4, .by-span-5, .by-span-6, .by-span-7, .by-span-8 { grid-column: span 12; }
}

@media (min-width: 1024px) {
  .by-footer__grid {
    grid-template-columns: 1.4fr 0.9fr 1.5fr 0.8fr;
    gap: clamp(20px, 3vw, 48px);
  }

  .by-footer__col--brand { padding-top: 6px; }
  .by-footer__col:nth-child(2) { padding-top: 26px; }
  .by-footer__col:nth-child(3) { padding-top: 12px; }
  .by-footer__col:nth-child(4) { padding-top: 34px; }
}

@media (min-width: 720px) {
  .by-footer__stamp { margin-left: auto; }
}

/* ---------- 9. 动效降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }

  .by-dot { animation: none; }

  .by-header__progress { transition: none; }
}