/* =========================================================================
   程泓宁 · 宇宙E-bike — Masterclass-style design system
   Cinematic dark · near-black · bold geometric sans · industrial-amber accent
   ========================================================================= */

/* ---- Fonts ---- */
@import url('https://fonts.googleapis.com/css2?family=Manrope:wght@400;500;600;700;800&family=Noto+Sans+SC:wght@300;400;500;700;900&family=Space+Mono:wght@400;700&display=swap');

:root{
  /* palette */
  --bg:#090807;
  --bg-2:#0E0C0A;
  --surface:#15120E;
  --surface-2:#1E1913;
  --line:rgba(244,239,230,.10);
  --line-2:rgba(244,239,230,.20);
  --text:#F4EFE6;
  --text-dim:#B9B1A1;
  --text-mute:#857D6E;
  --clay:#E2552A;
  --clay-bright:#F36B3E;
  --amber:#D8A24A;
  --amber-dim:#A9853F;

  /* type — bold geometric sans throughout (MasterClass-style) */
  --serif:"Manrope","Noto Sans SC",-apple-system,"PingFang SC","Microsoft YaHei",sans-serif;
  --serif-cn:"Noto Sans SC","Manrope",sans-serif;
  --sans:"Manrope","Noto Sans SC",-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;
  --mono:"Space Mono",ui-monospace,SFMono-Regular,Menlo,monospace;

  --maxw:1280px;
  --pad:clamp(20px,5vw,64px);
}

*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body{
  font-family:var(--sans);
  background:var(--bg);
  color:var(--text);
  line-height:1.6;
  font-size:17px;
  font-weight:400;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
  overflow-x:hidden;
}
img{display:block;max-width:100%}
a{color:inherit;text-decoration:none}
::selection{background:var(--clay);color:#fff}

/* ---- Layout helpers ---- */
.wrap{max-width:var(--maxw);margin:0 auto;padding-inline:var(--pad)}
.wrap-wide{max-width:1480px;margin:0 auto;padding-inline:var(--pad)}
section{position:relative}
.pad-y{padding-block:clamp(72px,11vw,160px)}
.pad-y-sm{padding-block:clamp(56px,8vw,104px)}
.divider{height:1px;background:var(--line);border:0}

/* ---- Type ---- */
.serif{font-family:var(--serif)}
.display{
  font-family:var(--serif);
  font-weight:800;
  line-height:1.08;
  letter-spacing:-.022em;
  text-wrap:balance;
}
h1.display{font-size:clamp(2.6rem,6.4vw,5.4rem)}
h2.display{font-size:clamp(1.9rem,4.2vw,3.5rem)}
h3.display{font-size:clamp(1.45rem,2.6vw,2.1rem);font-weight:700}
.lead{font-size:clamp(1.05rem,1.5vw,1.3rem);color:var(--text-dim);line-height:1.7;font-weight:400;max-width:54ch;text-wrap:pretty}

/* eyebrow / kicker */
.eyebrow{
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:.34em;
  text-transform:uppercase;
  color:var(--amber);
  display:inline-flex;align-items:center;gap:.85em;
  font-weight:400;
}
.eyebrow::before{
  content:"";width:34px;height:1px;background:var(--amber);opacity:.7;
}
.eyebrow.no-rule::before{display:none}

.section-head{max-width:760px}
.section-head .eyebrow{margin-bottom:26px}
.section-head h2{margin-bottom:22px}

.accent{color:var(--clay-bright)}
.amber{color:var(--amber)}
.muted{color:var(--text-mute)}
.dim{color:var(--text-dim)}

/* ---- Buttons ---- */
.btn{
  display:inline-flex;align-items:center;gap:.6em;
  font-family:var(--sans);font-weight:500;font-size:.95rem;
  padding:15px 28px;border-radius:999px;
  transition:transform .25s ease,background .25s ease,color .25s ease,border-color .25s ease;
  cursor:pointer;border:1px solid transparent;white-space:nowrap;
}
.btn .arrow{transition:transform .25s ease}
.btn:hover .arrow{transform:translateX(4px)}
.btn-primary{background:var(--clay);color:#fff}
.btn-primary:hover{background:var(--clay-bright)}
.btn-ghost{background:transparent;color:var(--text);border-color:var(--line-2)}
.btn-ghost:hover{border-color:var(--text);background:rgba(244,239,230,.05)}
.btn-lg{padding:18px 34px;font-size:1.02rem}

/* text link */
.tlink{
  display:inline-flex;align-items:center;gap:.5em;
  font-family:var(--mono);font-size:.82rem;letter-spacing:.08em;
  color:var(--text);border-bottom:1px solid var(--line-2);
  padding-bottom:3px;transition:color .2s,border-color .2s;
}
.tlink:hover{color:var(--amber);border-color:var(--amber)}
.tlink .arrow{transition:transform .25s ease}
.tlink:hover .arrow{transform:translate(3px,-3px)}

/* ---- Placeholder (image stand-ins) ---- */
.ph{
  position:relative;overflow:hidden;
  background:
    repeating-linear-gradient(135deg,rgba(244,239,230,.045) 0 1px,transparent 1px 11px),
    linear-gradient(160deg,#1c1812,#121009);
  display:flex;align-items:center;justify-content:center;
}
.ph::after{
  content:attr(data-label);
  font-family:var(--mono);font-size:11px;letter-spacing:.16em;text-transform:uppercase;
  color:rgba(244,239,230,.38);text-align:center;line-height:1.7;padding:0 1.6em;max-width:90%;
}
.ph-amber{
  background:
    repeating-linear-gradient(135deg,rgba(216,162,74,.07) 0 1px,transparent 1px 11px),
    linear-gradient(160deg,#221a10,#15110a);
}

/* ---- Nav ---- */
.nav{
  position:fixed;top:0;left:0;right:0;z-index:80;
  display:flex;align-items:center;justify-content:space-between;
  padding:20px var(--pad);
  transition:background .35s ease,border-color .35s ease,padding .35s ease;
  border-bottom:1px solid transparent;
}
.nav.scrolled{background:rgba(12,10,7,.86);backdrop-filter:blur(14px);border-bottom-color:var(--line);padding-block:14px}
.brand{display:flex;align-items:center;gap:13px}
.brand-mark{
  width:42px;height:42px;border:1px solid var(--line-2);border-radius:50%;
  display:grid;place-items:center;font-family:var(--serif);font-size:20px;color:var(--text);
  flex:none;transition:border-color .3s,background .3s;
}
.brand:hover .brand-mark{border-color:var(--amber);background:rgba(216,162,74,.08)}
.brand-name{display:flex;flex-direction:column;line-height:1.15}
.brand-name b{font-weight:700;font-size:.98rem;letter-spacing:.01em}
.brand-name span{font-family:var(--mono);font-size:9.5px;letter-spacing:.28em;color:var(--text-mute);text-transform:uppercase}
.nav-links{display:flex;align-items:center;gap:26px}
.nav-links a{
  font-size:.9rem;color:var(--text-dim);font-weight:400;position:relative;transition:color .2s;white-space:nowrap;
}
.nav-links a:hover,.nav-links a.active{color:var(--text)}
.nav-links a.active::after{
  content:"";position:absolute;left:0;right:0;bottom:-7px;height:1px;background:var(--amber);
}
.nav-cta{margin-left:6px}
.nav-burger{display:none;flex-direction:column;gap:5px;background:none;border:0;cursor:pointer;padding:8px}
.nav-burger span{width:24px;height:1.5px;background:var(--text);transition:.3s}

/* mobile overlay menu */
.mobile-menu{
  position:fixed;inset:0;z-index:90;background:var(--bg-2);
  display:flex;flex-direction:column;justify-content:center;padding:var(--pad);
  transform:translateY(-100%);transition:transform .5s cubic-bezier(.6,0,.2,1),visibility 0s .5s;
  overflow:hidden;visibility:hidden;
}
.mobile-menu.open{visibility:visible;transition:transform .5s cubic-bezier(.6,0,.2,1),visibility 0s 0s}
.mobile-menu.open{transform:translateY(0)}
.mobile-menu .mclose{position:absolute;top:24px;right:var(--pad);background:none;border:0;color:var(--text);font-size:28px;cursor:pointer;line-height:1}
.mobile-menu a{
  font-family:var(--serif);font-size:clamp(1.8rem,7vw,2.6rem);font-weight:700;
  color:var(--text-dim);padding:11px 0;border-bottom:1px solid var(--line);transition:color .2s,padding-left .25s;
  display:flex;align-items:baseline;gap:16px;letter-spacing:-.01em;
}
.mobile-menu a:hover{color:var(--text);padding-left:10px}
.mobile-menu a i{font-family:var(--mono);font-size:.7rem;color:var(--amber);font-style:normal}

/* ---- Hero (page) ---- */
.page-hero{
  position:relative;min-height:64vh;display:flex;align-items:flex-end;
  padding-top:160px;padding-bottom:clamp(48px,7vw,90px);overflow:hidden;
}
.page-hero .ph-bg{position:absolute;inset:0;z-index:0}
.hero-scrim{position:absolute;inset:0;z-index:1;
  background:linear-gradient(180deg,rgba(12,10,7,.55) 0%,rgba(12,10,7,.2) 35%,rgba(12,10,7,.82) 100%),
             linear-gradient(90deg,rgba(12,10,7,.7),rgba(12,10,7,.1));
}
.page-hero .wrap{position:relative;z-index:2;width:100%}
.page-hero .eyebrow{margin-bottom:28px}
.page-hero h1{margin-bottom:30px;max-width:18ch}

/* ---- Cards ---- */
.card{
  display:flex;flex-direction:column;
  background:var(--surface);border:1px solid var(--line);
  border-radius:14px;overflow:hidden;
  transition:border-color .35s ease,transform .35s ease,background .35s ease;
}
.card:hover{border-color:var(--line-2);transform:translateY(-4px)}
.card .ph{aspect-ratio:16/10}
.card .ph img{width:100%;height:100%;object-fit:cover}
.card-img{overflow:hidden;position:relative;border-radius:14px}
.card-img .ph{transition:transform .6s cubic-bezier(.2,.6,.2,1);width:100%;height:100%}
.card:hover .card-img .ph{transform:scale(1.05)}
/* MasterClass-style media cards: rounded full-bleed image, text below on black, no box */
.card:has(.card-img){background:transparent;border:0;border-radius:0;overflow:visible}
.card:has(.card-img):hover{transform:translateY(-6px)}
.card:has(.card-img) .card-img{border:1px solid var(--line)}
.card:has(.card-img) .card-body{padding:18px 2px 0}
.card:has(.card-img) .card-meta{padding-top:12px}
.card-tag{
  position:absolute;top:14px;left:14px;z-index:2;
  font-family:var(--mono);font-size:10px;letter-spacing:.16em;text-transform:uppercase;
  background:rgba(9,8,7,.72);backdrop-filter:blur(6px);color:var(--text);
  padding:6px 11px;border-radius:6px;border:1px solid var(--line-2);
}
.card-tag.live{color:#fff;background:var(--clay);border-color:transparent}
.card-body{padding:24px 24px 28px;display:flex;flex-direction:column;gap:12px;flex:1}
.card-body h3{font-family:var(--serif);font-weight:700;font-size:1.28rem;line-height:1.22;letter-spacing:-.015em}
.card-body p{font-size:.94rem;color:var(--text-dim);line-height:1.6;font-weight:400}
.card-meta{margin-top:auto;display:flex;align-items:center;justify-content:space-between;padding-top:14px}
.card-meta .when{font-family:var(--mono);font-size:11px;letter-spacing:.1em;color:var(--text-mute)}

.play-badge{
  position:absolute;inset:0;display:grid;place-items:center;z-index:2;
  opacity:0;transition:opacity .35s ease;
}
.card:hover .play-badge{opacity:1}
.play-badge i{
  width:60px;height:60px;border-radius:50%;border:1px solid rgba(244,239,230,.7);
  background:rgba(12,10,7,.35);backdrop-filter:blur(4px);
  display:grid;place-items:center;
}
.play-badge i::after{content:"";border-left:14px solid var(--text);border-top:9px solid transparent;border-bottom:9px solid transparent;margin-left:4px}

/* grid utilities */
.grid{display:grid;gap:clamp(16px,2vw,26px)}
.g-2{grid-template-columns:repeat(2,1fr)}
.g-3{grid-template-columns:repeat(3,1fr)}
.g-4{grid-template-columns:repeat(4,1fr)}

/* ---- Index tiles (explore) ---- */
.tile{
  position:relative;display:flex;flex-direction:column;justify-content:space-between;
  min-height:210px;padding:28px;border:1px solid var(--line);border-radius:14px;
  background:var(--surface);overflow:hidden;transition:.4s;
}
.tile::before{content:"";position:absolute;inset:0;background:linear-gradient(135deg,rgba(226,85,42,.0),rgba(226,85,42,.08));opacity:0;transition:.4s}
.tile:hover{border-color:var(--line-2);transform:translateY(-4px)}
.tile:hover::before{opacity:1}
.tile .num{font-family:var(--serif);font-size:2.2rem;color:var(--text-mute);font-weight:700;transition:color .4s}
.tile:hover .num{color:var(--amber)}
.tile .tname{font-family:var(--serif);font-size:1.4rem;font-weight:700;position:relative;z-index:1;letter-spacing:-.01em}
.tile .tdesc{font-size:.86rem;color:var(--text-mute);margin-top:6px;position:relative;z-index:1}
.tile .corner{position:absolute;top:24px;right:24px;color:var(--text-mute);transition:.4s}
.tile:hover .corner{color:var(--clay-bright);transform:translate(3px,-3px)}

/* ---- Quote / idea ---- */
.quote-big{
  font-family:var(--serif);font-weight:700;
  font-size:clamp(1.55rem,3.4vw,2.8rem);line-height:1.3;letter-spacing:-.02em;
  text-wrap:balance;
}
.quote-row{display:flex;gap:22px;align-items:flex-start;padding-block:clamp(34px,5vw,56px);border-bottom:1px solid var(--line)}
.quote-row .qmark{font-family:var(--serif);font-size:3rem;color:var(--clay);line-height:.7;flex:none}
.quote-row .qattr{font-family:var(--mono);font-size:11px;letter-spacing:.14em;text-transform:uppercase;color:var(--text-mute);margin-top:18px}

/* ---- Stats ---- */
.stat{display:flex;flex-direction:column;gap:8px}
.stat .n{font-family:var(--serif);font-size:clamp(2.6rem,5vw,4rem);font-weight:800;color:var(--amber);line-height:1;letter-spacing:-.02em}
.stat .l{font-size:.92rem;color:var(--text-dim)}

/* ---- Spec table ---- */
.spec{width:100%;border-collapse:collapse;font-size:.92rem}
.spec td{padding:13px 0;border-bottom:1px solid var(--line);vertical-align:top}
.spec td:first-child{font-family:var(--mono);font-size:11px;letter-spacing:.12em;text-transform:uppercase;color:var(--text-mute);width:34%;padding-right:16px}
.spec td:last-child{color:var(--text);font-weight:400}

/* ---- List (course bullets) ---- */
.checklist{display:flex;flex-direction:column;gap:2px}
.checklist li{display:flex;gap:16px;align-items:flex-start;padding:16px 0;border-bottom:1px solid var(--line);list-style:none}
.checklist li .ix{font-family:var(--mono);font-size:11px;color:var(--amber);flex:none;margin-top:5px;letter-spacing:.1em}
.checklist li span{font-size:1.04rem;color:var(--text);font-weight:400;line-height:1.5}

/* ---- Timeline ---- */
.timeline{position:relative;padding-left:30px}
.timeline::before{content:"";position:absolute;left:4px;top:8px;bottom:8px;width:1px;background:var(--line-2)}
.tl-item{position:relative;padding-bottom:42px}
.tl-item:last-child{padding-bottom:0}
.tl-item::before{content:"";position:absolute;left:-30px;top:7px;width:9px;height:9px;border-radius:50%;background:var(--bg);border:1px solid var(--amber)}
.tl-item .yr{font-family:var(--mono);font-size:11px;letter-spacing:.14em;color:var(--amber);text-transform:uppercase}
.tl-item h4{font-family:var(--serif);font-size:1.3rem;font-weight:700;margin:8px 0 8px;letter-spacing:-.01em}
.tl-item p{font-size:.95rem;color:var(--text-dim);font-weight:400;max-width:60ch}

/* ---- Media links (video / audio per course) ---- */
.links-row{display:flex;flex-wrap:wrap;gap:10px;margin-top:auto;padding-top:14px}
.media-link{
  display:inline-flex;align-items:center;gap:8px;
  font-family:var(--mono);font-size:11px;letter-spacing:.06em;
  padding:9px 13px;border:1px solid var(--line-2);border-radius:9px;
  color:var(--text-dim);transition:border-color .2s,color .2s,background .2s;
}
.media-link:hover{border-color:var(--amber);color:var(--amber);background:rgba(216,162,74,.06)}
.media-link.pending{color:var(--text-mute);opacity:.75}
.media-link .ic{width:13px;height:13px;flex:none;display:inline-grid;place-items:center}
.media-link .ic.video::before{content:"";border-left:9px solid currentColor;border-top:6px solid transparent;border-bottom:6px solid transparent}
.media-link .ic.audio{position:relative}
.media-link .ic.audio::before{content:"";width:11px;height:11px;border:1.5px solid currentColor;border-radius:50%;box-sizing:border-box}
.media-link .ic.audio::after{content:"";position:absolute;width:3px;height:3px;border-radius:50%;background:currentColor}

/* ---- Short-video clips (vertical 9:16) ---- */
.clips{display:grid;grid-template-columns:repeat(5,1fr);gap:clamp(14px,1.6vw,22px)}
.clip{display:flex;flex-direction:column;gap:12px}
.clip .clip-img{position:relative;overflow:hidden;border-radius:14px;border:1px solid var(--line)}
.clip .clip-img .ph{aspect-ratio:9/16;width:100%;transition:transform .6s cubic-bezier(.2,.6,.2,1)}
.clip:hover .clip-img .ph{transform:scale(1.05)}
.clip h4{font-family:var(--serif);font-size:1.02rem;font-weight:700;line-height:1.25;letter-spacing:-.01em}
.clip p{font-size:.85rem;color:var(--text-mute);line-height:1.5;font-weight:400}
.clip .play-badge i{width:46px;height:46px}
@media (max-width:980px){.clips{grid-template-columns:repeat(3,1fr)}}
@media (max-width:560px){.clips{grid-template-columns:repeat(2,1fr)}}

/* ---- CTA band ---- */
.cta-band{position:relative;overflow:hidden}
.cta-band .ph-bg{position:absolute;inset:0;z-index:0;opacity:.5}
.cta-band .scrim{position:absolute;inset:0;z-index:1;background:linear-gradient(180deg,rgba(12,10,7,.85),rgba(12,10,7,.95))}
.cta-band .wrap{position:relative;z-index:2;text-align:center;display:flex;flex-direction:column;align-items:center;gap:30px}
.cta-band h2{max-width:20ch}
.cta-band .lead{text-align:center;margin-inline:auto}

/* ---- Footer ---- */
.footer{background:var(--bg-2);border-top:1px solid var(--line);padding-block:clamp(56px,7vw,88px)}
.footer-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr;gap:48px}
.footer .brand{margin-bottom:22px}
.footer-tag{color:var(--text-dim);font-weight:400;max-width:34ch;line-height:1.7}
.footer-tag b{color:var(--text);font-weight:700}
.footcol h5{font-family:var(--mono);font-size:11px;letter-spacing:.2em;text-transform:uppercase;color:var(--text-mute);margin-bottom:18px}
.footcol a{display:block;color:var(--text-dim);font-size:.95rem;padding:6px 0;font-weight:400;transition:color .2s}
.footcol a:hover{color:var(--text)}
.footer-bottom{display:flex;justify-content:space-between;align-items:center;gap:20px;flex-wrap:wrap;
  margin-top:56px;padding-top:28px;border-top:1px solid var(--line);
  font-family:var(--mono);font-size:11px;letter-spacing:.08em;color:var(--text-mute)}

/* ---- Form ---- */
.field{margin-bottom:22px}
.field label{display:block;font-family:var(--mono);font-size:11px;letter-spacing:.14em;text-transform:uppercase;color:var(--text-mute);margin-bottom:10px}
.field input,.field textarea,.field select{
  width:100%;background:var(--surface);border:1px solid var(--line);border-radius:4px;
  padding:14px 16px;color:var(--text);font-family:var(--sans);font-size:1rem;font-weight:300;
  transition:border-color .2s,background .2s;
}
.field input:focus,.field textarea:focus,.field select:focus{outline:none;border-color:var(--amber);background:var(--surface-2)}
.field textarea{resize:vertical;min-height:140px}

/* ---- Reveal animation ---- */
@media (prefers-reduced-motion:no-preference){
  .js-ready [data-reveal]{opacity:0;transform:translateY(26px);transition:opacity .9s cubic-bezier(.2,.6,.2,1),transform .9s cubic-bezier(.2,.6,.2,1)}
  .js-ready [data-reveal].in{opacity:1;transform:none}
  .js-ready [data-reveal][data-delay="1"]{transition-delay:.08s}
  .js-ready [data-reveal][data-delay="2"]{transition-delay:.16s}
  .js-ready [data-reveal][data-delay="3"]{transition-delay:.24s}
  .js-ready [data-reveal][data-delay="4"]{transition-delay:.32s}
}
/* snap to final state (fires after entrance; also rescues frozen-transition contexts) */
.reveal-snap [data-reveal]{opacity:1!important;transform:none!important;transition:none!important}

/* ---- Responsive ---- */
@media (max-width:980px){
  .footer-grid{grid-template-columns:1fr 1fr;gap:40px}
  .footer-grid .footcol-brand{grid-column:1/-1}
  .g-4{grid-template-columns:repeat(2,1fr)}
}
@media (max-width:820px){
  .nav-links{display:none}
  .nav-burger{display:flex}
  .g-3{grid-template-columns:repeat(2,1fr)}
  .split{grid-template-columns:1fr!important}
}
@media (max-width:560px){
  body{font-size:16px}
  .g-2,.g-3,.g-4{grid-template-columns:1fr}
  .footer-grid{grid-template-columns:1fr}
  .footer-bottom{flex-direction:column;align-items:flex-start;gap:10px}
}

/* split helper */
.split{display:grid;grid-template-columns:1fr 1fr;gap:clamp(36px,6vw,84px);align-items:center}
.split-asym{display:grid;grid-template-columns:1.15fr .85fr;gap:clamp(36px,6vw,80px);align-items:center}
@media (max-width:820px){.split-asym{grid-template-columns:1fr}}