/* ============================================================
   宝马740娱线 — 共享样式 /assets/site.css
   碳黑底 · 深蓝银灰结构 · 电光青与熔岩橙赛季强调
   ============================================================ */

/* ---------- Reset ---------- */
*,
*::before,
*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body,h1,h2,h3,h4,h5,p,ul,ol,li,figure,blockquote,dl,dd{margin:0}
ul,ol{padding:0;list-style:none}
button{font:inherit;color:inherit;background:none;border:0}
a{color:inherit;text-decoration:none}
img,svg{display:block;max-width:100%}
img{height:auto}
table{border-collapse:collapse;width:100%}

/* ---------- Tokens ---------- */
:root{
  --ink-950:#04070b;
  --ink-900:#070c13;
  --ink-800:#0c141d;
  --ink-700:#121d29;

  --blue-900:#061527;
  --blue-800:#0a2340;
  --blue-700:#0f3157;
  --blue-600:#15507f;

  --silver-100:#eff4f9;
  --silver-200:#d5dee7;
  --silver-300:#a9b7c6;
  --silver-400:#7f8e9e;

  --cyan:#18e2d4;
  --cyan-soft:rgba(24,226,212,.12);
  --cyan-line:rgba(24,226,212,.34);
  --flame:#ff5a1f;
  --flame-soft:rgba(255,90,31,.10);

  --line:rgba(140,166,190,.18);
  --line-strong:rgba(140,166,190,.36);

  --text:#dbe4ee;
  --muted:#8e9dad;

  --radius-cap:999px;
  --radius-sharp:2px;
  --wrap:1280px;
  --header-offset:112px;

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

  --shadow-soft:0 18px 42px rgba(0,0,0,.45);
}

/* ---------- Base ---------- */
html,body{min-height:100%}
body{
  font-family:var(--font-sans);
  font-size:16px;
  line-height:1.75;
  color:var(--text);
  background-color:var(--ink-950);
  background-image:
    linear-gradient(rgba(140,166,190,.055) 1px,transparent 1px),
    linear-gradient(90deg,rgba(140,166,190,.055) 1px,transparent 1px),
    radial-gradient(1100px 620px at 10% -12%,rgba(24,226,212,.10),transparent 62%),
    radial-gradient(900px 520px at 100% 2%,rgba(255,90,31,.09),transparent 60%),
    linear-gradient(180deg,var(--ink-900),var(--ink-950) 62%);
  background-size:48px 48px,48px 48px,auto,auto,auto;
  background-attachment:fixed;
  padding-top:var(--header-offset);
  overflow-x:hidden;
}
::selection{background:var(--cyan);color:#04121a}

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

/* ---------- Type helpers ---------- */
h1,h2,h3,h4{font-weight:700;color:var(--silver-100);line-height:1.25;letter-spacing:.02em}
.eyebrow{
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.28em;
  text-transform:uppercase;
  color:var(--cyan);
  display:block;
  margin-bottom:10px;
}
.display{
  font-size:clamp(2rem,5.2vw,3.6rem);
  line-height:1.04;
  font-weight:800;
  letter-spacing:.03em;
  text-transform:uppercase;
  color:var(--silver-100);
}
.section-title{font-size:clamp(1.25rem,2.4vw,1.7rem);letter-spacing:.04em}
.lede{font-size:1.05rem;color:var(--silver-300);max-width:64ch}
.prose p{margin-bottom:1em;color:var(--silver-300)}
.prose p:last-child{margin-bottom:0}
.mono{font-family:var(--font-mono);letter-spacing:.04em}
.text-cyan{color:var(--cyan)}
.text-flame{color:var(--flame)}
.visually-hidden{
  position:absolute!important;width:1px;height:1px;padding:0;margin:-1px;
  overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0;
}

/* ---------- Skip link ---------- */
.skip-link{
  position:fixed;
  top:10px;left:20px;
  z-index:120;
  transform:translateY(-160%);
  padding:10px 18px;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.16em;
  color:#04121a;
  background:var(--cyan);
  border-radius:var(--radius-sharp);
  transition:transform .18s ease;
}
.skip-link:focus{transform:translateY(0)}

/* ---------- Layout ---------- */
.wrap{width:100%;max-width:var(--wrap);margin:0 auto;padding:0 20px}
.section{padding:56px 0}
.section--tight{padding:30px 0}
.rule{height:1px;border:0;background:var(--line);margin:0}
.grid{display:grid;gap:18px}
.grid--2{grid-template-columns:repeat(2,minmax(0,1fr))}
.grid--3{grid-template-columns:repeat(3,minmax(0,1fr))}
.grid--4{grid-template-columns:repeat(4,minmax(0,1fr))}

/* ---------- Breadcrumb ---------- */
.breadcrumb{padding:18px 0 0}
.breadcrumb ol{
  display:flex;flex-wrap:wrap;align-items:center;gap:8px;
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.1em;
  color:var(--silver-400);
}
.breadcrumb li+li::before{content:"/";margin-right:8px;color:var(--silver-400);opacity:.6}
.breadcrumb a{color:var(--silver-300)}
.breadcrumb a:hover{color:var(--cyan)}
.breadcrumb [aria-current="page"]{color:var(--cyan)}

/* ---------- Buttons ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  padding:11px 20px;
  font-size:13.5px;font-weight:600;letter-spacing:.08em;
  color:var(--silver-100);
  background:rgba(18,29,41,.82);
  border:1px solid var(--line-strong);
  border-radius:var(--radius-sharp);
  cursor:pointer;
  transition:color .18s ease,background .18s ease,border-color .18s ease,box-shadow .18s ease,transform .18s ease;
}
.btn:hover{border-color:var(--cyan);color:var(--cyan)}
.btn:active{transform:translateY(1px)}
.btn--primary{
  color:#04121a;
  background:linear-gradient(135deg,var(--cyan),#0db2a6);
  border-color:transparent;
}
.btn--primary:hover{color:#04121a;filter:brightness(1.07);box-shadow:0 10px 26px rgba(24,226,212,.26)}
.btn--flame{
  color:#180601;
  background:linear-gradient(135deg,var(--flame),#d43f0a);
  border-color:transparent;
}
.btn--flame:hover{color:#180601;filter:brightness(1.06);box-shadow:0 10px 26px rgba(255,90,31,.26)}
.btn--ghost{background:transparent}
.btn--sm{padding:8px 14px;font-size:12px;letter-spacing:.1em}

/* ---------- Tags ---------- */
.tag{
  display:inline-flex;align-items:center;gap:6px;
  padding:4px 10px;
  font-family:var(--font-mono);
  font-size:10.5px;letter-spacing:.14em;text-transform:uppercase;
  color:var(--cyan);
  background:var(--cyan-soft);
  border:1px solid var(--cyan-line);
  border-radius:var(--radius-sharp);
}
.tag--flame{color:var(--flame);background:var(--flame-soft);border-color:rgba(255,90,31,.38)}
.tag--muted{color:var(--silver-400);background:transparent;border-color:var(--line)}

/* ---------- Cards / Panels ---------- */
.card{
  position:relative;
  padding:22px;
  background:linear-gradient(158deg,rgba(12,20,29,.96),rgba(7,12,19,.9));
  border:1px solid var(--line);
  border-radius:var(--radius-sharp);
  transition:border-color .18s ease,transform .18s ease,box-shadow .18s ease;
}
.card::before{
  content:"";position:absolute;top:0;left:0;width:44px;height:2px;background:var(--cyan);
}
.card:hover{border-color:var(--line-strong);transform:translateY(-2px);box-shadow:var(--shadow-soft)}
.card__meta{font-family:var(--font-mono);font-size:11px;letter-spacing:.18em;text-transform:uppercase;color:var(--silver-400)}
.card__title{margin-top:8px;font-size:1.14rem;font-weight:700;color:var(--silver-100);letter-spacing:.04em}
.card__body{margin-top:10px;font-size:.94rem;color:var(--silver-300)}
.card--flame::before{background:var(--flame)}

.panel{
  padding:26px;
  background:rgba(9,15,22,.72);
  border:1px solid var(--line);
  border-radius:var(--radius-sharp);
}
.panel--accent{border-left:2px solid var(--cyan)}
.panel--flame{border-left:2px solid var(--flame)}

/* ---------- Stats ---------- */
.stat{
  padding:14px 16px;
  background:rgba(10,16,23,.72);
  border:1px solid var(--line);
  border-radius:var(--radius-sharp);
}
.stat__value{
  display:block;
  font-family:var(--font-mono);
  font-size:1.45rem;font-weight:600;letter-spacing:.02em;
  color:var(--cyan);
}
.stat--flame .stat__value{color:var(--flame)}
.stat__label{
  display:block;margin-top:4px;
  font-size:11.5px;letter-spacing:.16em;text-transform:uppercase;color:var(--silver-400);
}

/* ---------- Timeline (赛季轴) ---------- */
.timeline{position:relative;padding-left:22px;border-left:1px solid var(--line)}
.timeline__item{position:relative;padding-bottom:22px}
.timeline__item:last-child{padding-bottom:0}
.timeline__item::before{
  content:"";position:absolute;left:-27px;top:8px;
  width:9px;height:9px;
  background:var(--ink-950);
  border:1px solid var(--cyan);
  border-radius:50%;
}
.timeline__item[aria-current="true"]::before{
  background:var(--flame);border-color:var(--flame);
  box-shadow:0 0 10px rgba(255,90,31,.6);
}
.timeline__label{display:block;font-family:var(--font-mono);font-size:11px;letter-spacing:.16em;color:var(--cyan)}
.timeline__title{display:block;font-size:.98rem;font-weight:600;color:var(--silver-100)}

/* ---------- Accordion (可展开内容组) ---------- */
.accordion{border-top:1px solid var(--line)}
.accordion__item{border-bottom:1px solid var(--line)}
.accordion__trigger{
  display:flex;width:100%;align-items:center;justify-content:space-between;gap:16px;
  padding:18px 4px;
  font-size:1rem;font-weight:600;color:var(--silver-100);text-align:left;
  cursor:pointer;
  transition:color .18s ease;
}
.accordion__trigger:hover{color:var(--cyan)}
.accordion__icon{position:relative;flex:0 0 auto;width:14px;height:14px;color:var(--cyan)}
.accordion__icon::before,
.accordion__icon::after{content:"";position:absolute;background:currentColor}
.accordion__icon::before{left:0;right:0;top:6px;height:1.5px}
.accordion__icon::after{top:0;bottom:0;left:6px;width:1.5px;transition:transform .2s ease}
.accordion__trigger[aria-expanded="true"] .accordion__icon::after{transform:scaleY(0)}
.accordion__panel{padding:0 4px 20px;font-size:.95rem;color:var(--silver-300)}
.accordion__panel[hidden]{display:none}

/* ---------- Media (图片容器基础规则) ---------- */
.media{
  position:relative;overflow:hidden;
  aspect-ratio:16/10;
  background:linear-gradient(150deg,var(--blue-900),var(--ink-900));
  border:1px solid var(--line);
  border-radius:var(--radius-sharp);
}
.media img{width:100%;height:100%;object-fit:cover}
.media::after{
  content:"";position:absolute;inset:0;pointer-events:none;
  background-image:
    linear-gradient(rgba(140,166,190,.14) 1px,transparent 1px),
    linear-gradient(90deg,rgba(140,166,190,.14) 1px,transparent 1px);
  background-size:36px 36px;
  opacity:.42;
}
.media--wide{aspect-ratio:21/9}
.media--square{aspect-ratio:1/1}
.media--tall{aspect-ratio:3/4}
.media__caption{
  position:absolute;left:0;bottom:0;z-index:2;
  padding:8px 12px;
  font-family:var(--font-mono);font-size:10.5px;letter-spacing:.16em;
  color:var(--silver-200);
  background:rgba(4,7,11,.74);
}
.media--ph{
  display:grid;place-items:center;
  font-family:var(--font-mono);font-size:11px;letter-spacing:.2em;color:var(--silver-400);
}

/* ---------- Scroll progress ---------- */
.scroll-progress{
  position:fixed;top:0;left:0;z-index:110;
  width:100%;height:2px;
  transform:scaleX(0);transform-origin:0 50%;
  background:linear-gradient(90deg,var(--cyan),var(--flame));
  pointer-events:none;
}

/* ---------- Reveal ---------- */
html.js [data-reveal]{opacity:0;transform:translateY(14px)}
html.js [data-reveal].is-visible{
  opacity:1;transform:none;
  transition:opacity .5s ease,transform .5s ease;
}

/* ============================================================
   Header
   ============================================================ */
.site-header{
  position:fixed;top:0;left:0;right:0;z-index:100;
  padding:14px 20px;
  pointer-events:none;
}
.header-inner{
  pointer-events:auto;
  position:relative;
  display:grid;
  grid-template-columns:auto 1fr auto;
  align-items:center;
  gap:18px;
  max-width:var(--wrap);
  margin:0 auto;
  padding:8px 10px 8px 18px;
  background:rgba(7,12,19,.88);
  border:1px solid var(--line-strong);
  border-radius:var(--radius-cap);
  backdrop-filter:blur(14px) saturate(140%);
  -webkit-backdrop-filter:blur(14px) saturate(140%);
  box-shadow:var(--shadow-soft),inset 0 1px 0 rgba(255,255,255,.05);
}

/* 品牌 */
.brand{
  display:inline-flex;align-items:center;gap:10px;
  padding:4px 6px;
  border-radius:var(--radius-sharp);
}
.brand__mark{
  position:relative;
  flex:0 0 auto;
  width:30px;height:30px;
  display:grid;place-items:center;
  border:1px solid var(--line-strong);
  border-radius:50%;
  background:linear-gradient(135deg,var(--blue-800),var(--ink-900));
}
.brand__mark::before{
  content:"";width:13px;height:13px;border-radius:50%;
  border:2px solid var(--cyan);border-right-color:var(--flame);
}
.brand__text{display:flex;flex-direction:column;line-height:1.15}
.brand__name{font-size:15px;font-weight:700;letter-spacing:.12em;color:var(--silver-100)}
.brand__sub{
  font-family:var(--font-mono);
  font-size:9px;letter-spacing:.28em;text-transform:uppercase;
  color:var(--cyan);
}
.brand:hover .brand__name{color:var(--cyan)}

/* 导航 */
.site-nav{display:flex;justify-content:center;min-width:0}
.nav-list{display:flex;align-items:center;gap:2px}
.nav-link{
  display:inline-block;
  padding:9px 13px;
  font-size:13.5px;letter-spacing:.06em;
  color:var(--silver-300);
  border:1px solid transparent;
  border-radius:var(--radius-sharp);
  transition:color .18s ease,background .18s ease,border-color .18s ease;
}
.nav-link:hover{color:var(--silver-100);background:var(--cyan-soft);border-color:var(--cyan-line)}
.nav-link[aria-current="page"]{
  color:#04121a;font-weight:600;
  background:linear-gradient(180deg,var(--cyan),#0fb9ae);
  border-color:rgba(24,226,212,.9);
  box-shadow:0 8px 18px rgba(24,226,212,.22);
}

/* 头部右侧 */
.header-actions{display:flex;align-items:center;gap:10px;justify-self:end}
.season-chip{
  display:inline-flex;align-items:center;gap:7px;
  padding:6px 12px;
  font-family:var(--font-mono);font-size:10.5px;letter-spacing:.16em;
  color:var(--silver-300);
  background:rgba(12,20,29,.72);
  border:1px solid var(--line);
  border-radius:var(--radius-cap);
  white-space:nowrap;
}
.season-chip__dot{
  width:6px;height:6px;border-radius:50%;
  background:var(--cyan);box-shadow:0 0 8px var(--cyan);
}

/* 移动导航按钮 */
.nav-toggle{
  display:none;align-items:center;gap:8px;
  padding:8px 12px;
  font-size:12px;letter-spacing:.1em;
  color:var(--silver-200);
  background:rgba(12,20,29,.9);
  border:1px solid var(--line-strong);
  border-radius:var(--radius-cap);
  cursor:pointer;
  transition:color .18s ease,border-color .18s ease;
}
.nav-toggle:hover{border-color:var(--cyan);color:var(--cyan)}
.nav-toggle__bars{display:grid;gap:3px;width:16px}
.nav-toggle__bars span{
  display:block;height:1.5px;background:currentColor;
  transition:transform .2s ease,opacity .2s ease;
}
.nav-toggle__label{white-space:nowrap}
.nav-toggle[aria-expanded="true"]{border-color:var(--cyan);color:var(--cyan)}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(1){transform:translateY(4.5px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(2){opacity:0}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(3){transform:translateY(-4.5px) rotate(-45deg)}

/* ============================================================
   Footer
   ============================================================ */
.site-footer{
  position:relative;
  margin-top:80px;
  border-top:1px solid var(--line-strong);
  background:linear-gradient(180deg,rgba(6,21,39,.78),rgba(4,7,11,.99) 70%);
}
.site-footer::before{
  content:"";position:absolute;inset:0;pointer-events:none;
  background-image:
    linear-gradient(rgba(140,166,190,.07) 1px,transparent 1px),
    linear-gradient(90deg,rgba(140,166,190,.07) 1px,transparent 1px);
  background-size:60px 60px;
}
.footer-inner{position:relative;max-width:var(--wrap);margin:0 auto;padding:52px 20px 0}
.footer-grid{
  display:grid;
  grid-template-columns:1.5fr 1fr 1fr 1.3fr;
  gap:34px;
}
.footer-col{min-width:0}
.brand--footer{padding:0;margin-bottom:14px}
.brand--footer .brand__name{font-size:14px}
.footer-title{
  margin-bottom:14px;
  font-family:var(--font-mono);
  font-size:11px;letter-spacing:.24em;text-transform:uppercase;
  color:var(--cyan);
  font-weight:600;
}
.footer-note{font-size:13px;color:var(--silver-400);max-width:36ch;margin-bottom:10px}
.footer-note--quiet{color:var(--silver-400);opacity:.78;font-size:12.5px}
.footer-list{display:grid;gap:9px}
.footer-list a{
  display:inline-block;
  font-size:13.5px;color:var(--silver-300);
  transition:color .18s ease,transform .18s ease;
}
.footer-list a:hover{color:var(--cyan);transform:translateX(3px)}
.footer-list--plain li{
  display:grid;gap:2px;
  font-size:13px;
  padding-bottom:8px;
  border-bottom:1px solid rgba(140,166,190,.12);
}
.footer-list--plain li:last-child{border-bottom:0;padding-bottom:0}
.footer-key{
  font-family:var(--font-mono);font-size:10.5px;letter-spacing:.2em;
  text-transform:uppercase;color:var(--silver-400);
}
.footer-value{color:var(--silver-100);word-break:break-all}
.footer-cta{margin-top:16px}
.footer-bottom{
  display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:12px;
  margin-top:44px;
  padding:18px 0 26px;
  border-top:1px solid var(--line);
  font-family:var(--font-mono);
  font-size:11.5px;letter-spacing:.08em;
  color:var(--silver-400);
}
.footer-legal{white-space:nowrap}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width:1080px){
  .grid--4{grid-template-columns:repeat(2,minmax(0,1fr))}
  .grid--3{grid-template-columns:repeat(2,minmax(0,1fr))}
  .footer-grid{grid-template-columns:1.4fr 1fr 1fr;gap:28px}
  .footer-col--brand{grid-column:1/-1}
  .season-chip{display:none}
}

@media (max-width:980px){
  :root{--header-offset:104px}
  .site-header{padding:10px 12px}
  .header-inner{
    grid-template-columns:1fr auto;
    padding:10px 14px;
    border-radius:22px;
  }
  .nav-toggle{display:inline-flex}
  .header-actions .btn--sm{display:none}
  .site-nav{
    position:absolute;
    top:calc(100% + 10px);
    left:0;right:0;
    display:none;
    padding:10px;
    background:rgba(4,7,11,.97);
    border:1px solid var(--line-strong);
    border-radius:16px;
    box-shadow:var(--shadow-soft);
    backdrop-filter:blur(14px);
    -webkit-backdrop-filter:blur(14px);
  }
  .site-nav[data-open]{display:block}
  .nav-list{flex-direction:column;align-items:stretch;gap:2px}
  .nav-link{
    display:block;
    padding:13px 14px;
    border-bottom:1px solid rgba(140,166,190,.1);
  }
  .nav-list li:last-child .nav-link{border-bottom:0}
  .nav-link[aria-current="page"]{
    border-bottom-color:transparent;
    box-shadow:none;
  }
}

@media (max-width:680px){
  body{padding-top:100px;background-attachment:scroll}
  .wrap{padding:0 16px}
  .section{padding:40px 0}
  .grid--2,.grid--3,.grid--4{grid-template-columns:1fr}
  .footer-grid{grid-template-columns:1fr;gap:26px}
  .footer-inner{padding:42px 16px 0}
  .footer-bottom{font-size:11px;gap:8px}
  .footer-legal{white-space:normal}
  .brand__sub{letter-spacing:.2em}
}

/* ============================================================
   Motion preferences
   ============================================================ */
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{
    animation-duration:.001ms!important;
    animation-iteration-count:1!important;
    transition-duration:.001ms!important;
  }
  html.js [data-reveal]{opacity:1;transform:none}
  .card:hover{transform:none}
  .footer-list a:hover{transform:none}
}