/* =========================================================
   奔驰宝马开服 · 共享站点样式 /assets/site.css
   ========================================================= */

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
html.is-nav-open { overflow: hidden; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

body {
  margin: 0;
  background: var(--abyss-950);
  color: var(--silver-200);
  font-family: var(--font-display);
  font-size: 17px;
  line-height: 1.75;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4, h5, p, figure, blockquote, dl, dd { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; height: auto; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
strong, b { font-weight: 800; color: var(--silver-050); }
::selection { background: var(--benz-blue-500); color: #04121f; }

:root {
  --abyss-950: #070D18;
  --ink-900: #0C1626;
  --graphite-800: #16233A;
  --steel-600: #2A3A52;
  --silver-200: #C9D3DF;
  --silver-050: #F2F5F9;
  --benz-blue-500: #4EA8DE;
  --bmw-orange-500: #F08A3C;
  --cyan-glow-400: #3FE0C4;
  --mint-300: #7ED6A5;
  --muted-500: #7C8BA0;

  --rail-w: 84px;
  --rail-h: 62px;
  --container: 1280px;
  --radius-card: 26px;
  --radius-pill: 999px;
  --ease: cubic-bezier(0.2, 0.7, 0.3, 1);

  --font-display: "Source Han Sans SC", "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-serif: "Source Han Serif SC", "Noto Serif SC", "Songti SC", "SimSun", serif;
  --font-mono: "JetBrains Mono", "Roboto Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --font-condensed: "Barlow Condensed", "Oswald", "Arial Narrow", var(--font-display);
}

/* 桌面：内容让开左侧导轨 */
@media (min-width: 1024px) { body { padding-left: var(--rail-w); } }
/* 移动：内容让开顶部条 */
@media (max-width: 1023px) { body { padding-top: var(--rail-h); } }

:focus-visible {
  outline: 2px solid var(--cyan-glow-400);
  outline-offset: 3px;
  border-radius: 6px;
}

.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 200;
  padding: 11px 20px;
  border-radius: 12px;
  background: var(--cyan-glow-400);
  color: #04121f;
  font-weight: 800;
  font-size: 14px;
  letter-spacing: 0.04em;
  transform: translateY(-220%);
  transition: transform 0.2s var(--ease);
}
.skip-link:focus,
.skip-link:focus-visible { transform: translateY(0); }

/* =========================
   侧边导轨头部
   ========================= */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 60;
  width: var(--rail-w);
  height: 100vh;
  height: 100dvh;
}

.rail {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 14px;
  height: 100%;
  padding: 18px 0 20px;
  background:
    linear-gradient(180deg, #0A1424 0%, #070D18 52%, #0A1424 100%);
  border-right: 1px solid var(--steel-600);
}
.rail::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: 9px;
  width: 1px;
  background: repeating-linear-gradient(
    to bottom,
    var(--steel-600) 0 2px,
    transparent 2px 12px
  );
  opacity: 0.5;
  pointer-events: none;
}
.rail::after {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  right: 0;
  width: 1px;
  background: linear-gradient(180deg, transparent, var(--benz-blue-500), transparent);
  opacity: 0.35;
  pointer-events: none;
}

.rail__brand {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  padding: 4px 2px;
  color: var(--silver-050);
  border-radius: 16px;
  transition: color 0.24s var(--ease);
}
.rail__brand-mark {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--benz-blue-500), var(--cyan-glow-400));
  color: #04121f;
  font-family: var(--font-condensed);
  font-weight: 600;
  font-size: 15px;
  letter-spacing: 0.12em;
  line-height: 1;
}
.rail__brand-cn {
  writing-mode: vertical-rl;
  font-size: 14px;
  font-weight: 900;
  letter-spacing: 0.2em;
  line-height: 1;
}

.rail__toggle {
  display: none;
  align-items: center;
  gap: 9px;
  padding: 9px 15px;
  border: 1px solid var(--steel-600);
  border-radius: var(--radius-pill);
  background: var(--graphite-800);
  color: var(--silver-050);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  transition: border-color 0.24s var(--ease), color 0.24s var(--ease);
}
.rail__toggle:hover { border-color: var(--benz-blue-500); color: var(--benz-blue-500); }
.rail__toggle-icon { display: flex; flex-direction: column; gap: 3px; width: 16px; }
.rail__toggle-bar {
  display: block;
  height: 1.5px;
  width: 100%;
  border-radius: 2px;
  background: currentColor;
  transition: transform 0.26s var(--ease), opacity 0.26s var(--ease);
}
.site-header[data-open] .rail__toggle-bar:nth-child(1) { transform: translateY(4.5px) rotate(45deg); }
.site-header[data-open] .rail__toggle-bar:nth-child(2) { opacity: 0; }
.site-header[data-open] .rail__toggle-bar:nth-child(3) { transform: translateY(-4.5px) rotate(-45deg); }

.rail__nav {
  display: flex;
  flex: 1;
  min-height: 0;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 6px;
  width: 100%;
  padding-block: 8px;
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-width: none;
}
.rail__nav::-webkit-scrollbar { display: none; }

.rail__list {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  width: 100%;
}
.rail__item { display: block; }

.rail__link {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 9px 8px;
  border-radius: 16px;
  color: var(--silver-200);
  transition: color 0.24s var(--ease), background-color 0.24s var(--ease);
}
.rail__link:hover { color: var(--silver-050); background: rgba(78, 168, 222, 0.12); }
.rail__link[aria-current="page"] {
  background: var(--benz-blue-500);
  color: #04121f;
}
.rail__link[aria-current="page"] .rail__no { color: rgba(4, 18, 31, 0.62); }

.rail__no {
  display: none;
  font-family: var(--font-mono);
  font-size: 9px;
  letter-spacing: 0.1em;
  line-height: 1;
  color: var(--muted-500);
}
.rail__label {
  writing-mode: vertical-rl;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.16em;
  line-height: 1;
}

.rail__utility {
  display: none;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  width: 56px;
  margin-top: 8px;
  padding-top: 12px;
  border-top: 1px solid var(--steel-600);
}
.rail__utility-link {
  writing-mode: vertical-rl;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  line-height: 1.2;
  color: var(--muted-500);
  transition: color 0.22s var(--ease);
}
.rail__utility-link:hover { color: var(--benz-blue-500); }

.rail__cta {
  writing-mode: vertical-rl;
  padding-block: 9px;
  padding-inline: 18px;
  border-radius: var(--radius-pill);
  background: var(--bmw-orange-500);
  color: #180a01;
  font-size: 12px;
  font-weight: 900;
  letter-spacing: 0.14em;
  line-height: 1;
  transition: background-color 0.24s var(--ease), transform 0.24s var(--ease);
}
.rail__cta:hover { background: #ffa25c; transform: translateY(-2px); }

.rail__scrim { display: none; }

/* =========================
   页脚
   ========================= */
.site-footer {
  position: relative;
  margin-top: clamp(56px, 8vw, 120px);
  background: linear-gradient(180deg, var(--ink-900) 0%, var(--abyss-950) 74%);
  overflow: hidden;
}
.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent 0%, var(--benz-blue-500) 28%, var(--bmw-orange-500) 72%, transparent 100%);
  opacity: 0.55;
}
.site-footer::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(
    to right,
    rgba(42, 58, 82, 0.55) 0 1px,
    transparent 1px 34px
  );
  opacity: 0.22;
  pointer-events: none;
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.7), transparent 46%);
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.7), transparent 46%);
}

.footer__inner {
  position: relative;
  z-index: 1;
  max-width: var(--container);
  margin-inline: auto;
  padding: clamp(44px, 6vw, 80px) clamp(20px, 4vw, 56px) 0;
}

.footer__top { display: grid; gap: clamp(28px, 4vw, 56px); }

.footer__brand { display: flex; flex-direction: column; gap: 16px; }
.footer__brand-link {
  display: flex;
  align-items: center;
  gap: 14px;
  border-radius: 14px;
}
.footer__brand-mark {
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  width: 40px;
  height: 40px;
  border-radius: 13px;
  background: linear-gradient(135deg, var(--benz-blue-500), var(--cyan-glow-400));
  color: #04121f;
  font-family: var(--font-condensed);
  font-size: 17px;
  font-weight: 600;
  letter-spacing: 0.1em;
  line-height: 1;
}
.footer__brand-line {
  font-size: clamp(15px, 1.6vw, 18px);
  font-weight: 800;
  letter-spacing: 0.01em;
  color: var(--silver-050);
}
.footer__note {
  max-width: 34ch;
  font-size: 14px;
  line-height: 1.75;
  color: var(--muted-500);
}

.footer__cols {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(96px, 1fr));
  gap: 24px 26px;
}
.footer__col { min-width: 0; }
.footer__col-title {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 400;
  letter-spacing: 0.16em;
  line-height: 1;
  color: var(--benz-blue-500);
}
.footer__list { display: flex; flex-direction: column; gap: 10px; }

.footer__link {
  position: relative;
  display: inline-block;
  font-size: 15px;
  color: var(--silver-200);
  transition: color 0.22s var(--ease);
}
.footer__link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -3px;
  width: 100%;
  height: 1px;
  background: var(--benz-blue-500);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.26s var(--ease);
}
.footer__link:hover { color: var(--silver-050); }
.footer__link:hover::after { transform: scaleX(1); }

.footer__contact { min-width: 0; }
.footer__contact-item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  align-items: baseline;
  gap: 4px 12px;
  font-size: 14px;
}
.footer__contact-label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  line-height: 1.6;
  color: var(--muted-500);
  white-space: nowrap;
}
.footer__contact-value {
  color: var(--silver-200);
  line-height: 1.6;
  overflow-wrap: anywhere;
}

.footer__base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 24px;
  margin-top: clamp(28px, 4vw, 48px);
  padding-block: 20px 26px;
  border-top: 1px solid var(--steel-600);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--muted-500);
}
.footer__icp,
.footer__copy { line-height: 1.6; }

@media (min-width: 720px) {
  .footer__top { grid-template-columns: minmax(0, 1fr) minmax(0, 1.35fr); }
  .footer__contact { grid-column: 1 / -1; }
}
@media (min-width: 1080px) {
  .footer__top { grid-template-columns: minmax(0, 1.05fr) minmax(0, 1.4fr) minmax(0, 1fr); }
  .footer__contact { grid-column: auto; }
}

/* =========================
   通用排版与内容容器
   ========================= */
#main-content { display: block; }

.wrap {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: clamp(18px, 4vw, 48px);
}

.display {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(44px, 8vw, 120px);
  line-height: 0.95;
  letter-spacing: -0.04em;
  color: var(--silver-050);
}

.kicker {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: clamp(20px, 3vw, 34px);
  line-height: 1.3;
  letter-spacing: 0.01em;
  color: var(--silver-050);
}

.mono-note {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  line-height: 1.7;
  color: var(--muted-500);
}

.link-underline {
  position: relative;
  display: inline-block;
  color: var(--benz-blue-500);
}
.link-underline::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 100%;
  height: 1px;
  background: currentColor;
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.24s var(--ease);
}
.link-underline:hover::after { transform: scaleX(1); }

/* 章节 */
.section { padding-block: clamp(40px, 6vw, 88px); }
.section__no {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.16em;
  line-height: 1;
  color: var(--benz-blue-500);
}

/* 面包屑 */
.breadcrumbs { padding-top: clamp(16px, 3vw, 28px); }
.breadcrumbs__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--muted-500);
}
.breadcrumbs__item { display: inline-flex; align-items: center; gap: 8px; }
.breadcrumbs__item + .breadcrumbs__item::before {
  content: "/";
  color: var(--steel-600);
}
.breadcrumbs__link {
  color: var(--silver-200);
  transition: color 0.2s var(--ease);
}
.breadcrumbs__link:hover { color: var(--benz-blue-500); }
.breadcrumbs__current { color: var(--silver-050); }

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 13px 24px;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.04em;
  line-height: 1.2;
  transition: transform 0.22s var(--ease), background-color 0.22s var(--ease),
    border-color 0.22s var(--ease), color 0.22s var(--ease);
}
.btn:hover { transform: translateY(-2px); }
.btn--primary { background: var(--benz-blue-500); color: #04121f; }
.btn--primary:hover { background: #69bae7; }
.btn--ghost { background: transparent; color: var(--silver-050); border-color: var(--steel-600); }
.btn--ghost:hover { border-color: var(--benz-blue-500); color: var(--benz-blue-500); }

/* 胶囊标签 */
.pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 12px;
  border: 1px solid var(--steel-600);
  border-radius: var(--radius-pill);
  background: rgba(22, 35, 58, 0.62);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  line-height: 1.5;
  color: var(--silver-200);
}
.pill--blue { color: var(--benz-blue-500); border-color: rgba(78, 168, 222, 0.45); }
.pill--orange { color: var(--bmw-orange-500); border-color: rgba(240, 138, 60, 0.45); }
.pill--mint { color: var(--mint-300); border-color: rgba(126, 214, 165, 0.45); }

/* 卡片 */
.card {
  padding: clamp(20px, 3vw, 32px);
  border: 1px solid var(--steel-600);
  border-radius: var(--radius-card);
  background: var(--graphite-800);
  transition: transform 0.24s var(--ease), border-color 0.24s var(--ease);
}
.card:hover { transform: translateY(-2px); border-color: var(--benz-blue-500); }

/* 非对称双栏 */
.split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 4vw, 56px);
}
@media (min-width: 900px) {
  .split { grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); }
  .split--wide { grid-template-columns: minmax(0, 8fr) minmax(0, 4fr); }
}

/* 响应式图片容器 */
.media {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--steel-600);
  border-radius: var(--radius-card);
  background: linear-gradient(140deg, var(--graphite-800), var(--ink-900));
  aspect-ratio: 16 / 10;
}
.media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.32s var(--ease);
}
.media:hover img { transform: scale(1.02); }
.media--wide { aspect-ratio: 21 / 9; }
.media--tall { aspect-ratio: 4 / 5; }
.media--square { aspect-ratio: 1 / 1; }
.media__caption {
  position: absolute;
  left: 14px;
  bottom: 14px;
  padding: 5px 12px;
  border-radius: var(--radius-pill);
  background: rgba(7, 13, 24, 0.78);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--silver-200);
}

/* 进入视口显现 */
[data-reveal] {
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.32s var(--ease), transform 0.32s var(--ease);
}
[data-reveal].is-revealed { opacity: 1; transform: none; }

/* =========================
   移动端：抽屉导航
   ========================= */
@media (max-width: 1023px) {
  .site-header {
    top: 0;
    left: 0;
    right: 0;
    bottom: auto;
    width: 100%;
    height: var(--rail-h);
  }
  .rail {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    height: var(--rail-h);
    padding: 0 16px;
    border-right: 0;
    border-bottom: 1px solid var(--steel-600);
  }
  .rail::before,
  .rail::after { display: none; }

  .rail__brand {
    flex-direction: row;
    align-items: center;
    gap: 10px;
    padding: 0;
  }
  .rail__brand-mark { width: 28px; height: 28px; border-radius: 9px; font-size: 13px; }
  .rail__brand-cn { writing-mode: horizontal-tb; font-size: 14px; letter-spacing: 0.02em; }

  .rail__toggle { display: flex; }

  .rail__nav {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    z-index: 2;
    flex: none;
    justify-content: flex-start;
    align-items: stretch;
    gap: 4px;
    width: min(84vw, 330px);
    height: 100vh;
    height: 100dvh;
    padding: calc(var(--rail-h) + 18px) 20px 28px;
    background: linear-gradient(160deg, #0C1626 0%, #070D18 72%);
    border-right: 1px solid var(--steel-600);
    overflow-y: auto;
    overscroll-behavior: contain;
    transform: translateX(-102%);
    transition: transform 0.3s var(--ease);
  }
  .site-header[data-open] .rail__nav { transform: translateX(0); }

  .rail__list { align-items: stretch; gap: 4px; }
  .rail__link {
    flex-direction: row;
    justify-content: flex-start;
    gap: 14px;
    padding: 14px 16px;
    border-radius: 16px;
  }
  .rail__no { display: block; font-size: 11px; }
  .rail__label { writing-mode: horizontal-tb; font-size: 16px; letter-spacing: 0.05em; }

  .rail__utility {
    display: flex;
    flex-direction: row;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
    width: auto;
    margin-top: 18px;
    padding-top: 18px;
    border-top: 1px solid var(--steel-600);
  }
  .rail__utility-link {
    writing-mode: horizontal-tb;
    padding: 7px 12px;
    border: 1px solid var(--steel-600);
    border-radius: var(--radius-pill);
    font-size: 11px;
    line-height: 1.2;
  }

  .rail__cta {
    writing-mode: horizontal-tb;
    display: block;
    margin-top: auto;
    padding: 15px 18px;
    text-align: center;
    font-size: 14px;
    letter-spacing: 0.08em;
  }

  .rail__scrim {
    display: block;
    position: fixed;
    inset: 0;
    z-index: 1;
    background: rgba(3, 7, 14, 0.72);
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.28s var(--ease), visibility 0.28s var(--ease);
  }
  .site-header[data-open] .rail__scrim { opacity: 1; visibility: visible; }
}

@media (min-width: 1024px) {
  .rail__toggle { display: none; }
}

/* 矮屏桌面：导轨内容从头排列，避免裁切 */
@media (min-width: 1024px) and (max-height: 800px) {
  .rail__nav { justify-content: flex-start; }
}

@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;
  }
  [data-reveal] { opacity: 1 !important; transform: none !important; }
  .btn:hover, .card:hover, .rail__cta:hover, .media:hover img { transform: none; }
}