/* ============================================================
   UX Hero · app.uxhero.design — design tokens + components
   Visual language: Vimeo (light, near-black ink, 12px radii,
   left-sidebar dashboard). Tokens extracted from vimeo.com.
   Font: ABC Repro (Vimeo, licensed) → Inter fallback.
   ============================================================ */
:root{
  /* surfaces */
  --bg:#F6F8FA;          /* app background */
  --surface:#FFFFFF;     /* cards, sidebar, bars */
  --surface-2:#EEF1F4;   /* hover / subtle fill / selected nav */
  --surface-3:#E3E7EB;   /* pressed */
  /* ink */
  --text:#0E1216;        /* primary near-black */
  --text-2:#5A6066;      /* secondary */
  --text-3:#8A9097;      /* faint / meta */
  --line:#E4E8EB;        /* borders */
  --line-2:#D3D9DE;
  /* brand / accents */
  --ink:#0E1216;         /* primary button bg */
  --ink-on:#F9FAFB;      /* text on primary */
  --purple:#875BE5;      /* Vimeo purple */
  --purple-ink:#FFFFFF;
  --blue:#1A8CFF;        /* links */
  --orange:#FF5C2B;      /* course accent (DE) */
  --green:#1BB66E;
  /* radii + shadow */
  --r:12px; --r-sm:8px; --r-xs:6px; --r-pill:100px;
  --shadow-sm:0 1px 2px rgba(14,18,22,.05);
  --shadow:0 4px 18px rgba(14,18,22,.08);
  --shadow-lg:0 18px 50px rgba(14,18,22,.16);
  --sidebar-w:240px;
  --font:'Inter',-apple-system,BlinkMacSystemFont,'Segoe UI','Helvetica Neue',Arial,sans-serif;
}
[data-theme="dark"]{
  --bg:#0E1216; --surface:#171B20; --surface-2:#21262C; --surface-3:#2A3036;
  --text:#F4F6F8; --text-2:#A4ABB2; --text-3:#767D84; --line:#272D33; --line-2:#323941;
  --ink:#FFFFFF; --ink-on:#0E1216; --shadow:0 4px 18px rgba(0,0,0,.4); --shadow-sm:0 1px 2px rgba(0,0,0,.3); --shadow-lg:0 18px 50px rgba(0,0,0,.6);
}
*{box-sizing:border-box;margin:0;padding:0}
html{background:var(--bg)}
body{background:var(--bg);color:var(--text);font-family:var(--font);line-height:1.5;-webkit-font-smoothing:antialiased;font-feature-settings:'cv11','ss01';letter-spacing:-.005em}
a{color:inherit;text-decoration:none}
.muted{color:var(--text-2)}
.hidden{display:none!important}
.wrap{max-width:1080px;margin:0 auto;padding:0 24px}

/* ---------- buttons ---------- */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;height:40px;padding:0 16px;border:1px solid var(--line-2);border-radius:var(--r);background:var(--surface);color:var(--text);font-family:inherit;font-size:14px;font-weight:600;cursor:pointer;white-space:nowrap;transition:background .15s,border-color .15s,transform .05s}
.btn:hover{background:var(--surface-2)}
.btn:active{transform:translateY(.5px)}
.btn.primary{background:var(--ink);color:var(--ink-on);border-color:var(--ink)}
.btn.primary:hover{opacity:.9;background:var(--ink)}
.btn.purple{background:var(--purple);color:var(--purple-ink);border-color:var(--purple)}
.btn.purple:hover{opacity:.92;background:var(--purple)}
.btn.ghost{background:transparent;border-color:transparent}
.btn.ghost:hover{background:var(--surface-2)}
.btn.sm{height:32px;padding:0 12px;font-size:13px}
.btn.lg{height:48px;padding:0 22px;font-size:15px}
.btn.block{width:100%}

/* ---------- theme toggle (animated sun/moon switch) ---------- */
.theme-toggle{border:none;background:transparent;padding:3px;cursor:pointer;display:inline-flex;border-radius:var(--r-pill);-webkit-tap-highlight-color:transparent}
.tt-track{position:relative;width:52px;height:28px;border-radius:var(--r-pill);background:var(--surface-2);border:1px solid var(--line);transition:background .3s ease,border-color .3s ease}
.tt-knob{position:absolute;top:2px;left:2px;width:22px;height:22px;border-radius:50%;background:var(--surface);box-shadow:0 2px 6px rgba(14,18,22,.22);transition:transform .36s cubic-bezier(.5,1.45,.5,1),background .3s ease}
.theme-toggle:active .tt-knob{transform:scale(.92)}
[data-theme="dark"] .tt-track{background:#2A3036;border-color:#323941}
[data-theme="dark"] .tt-knob{transform:translateX(24px);background:#0E1216}
[data-theme="dark"] .theme-toggle:active .tt-knob{transform:translateX(24px) scale(.92)}
.tt-ic{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;font-size:12.5px;line-height:1;transition:opacity .3s ease,transform .42s ease}
.tt-sun{color:#FF9500;opacity:1;transform:rotate(0) scale(1)}
.tt-moon{color:#DDE3E8;opacity:0;transform:rotate(-90deg) scale(.5)}
[data-theme="dark"] .tt-sun{opacity:0;transform:rotate(90deg) scale(.5)}
[data-theme="dark"] .tt-moon{opacity:1;transform:rotate(0) scale(1)}
.theme-fixed{position:fixed;top:18px;right:18px;z-index:40}

/* ---------- landing topbar ---------- */
.topbar{position:sticky;top:0;z-index:30;background:color-mix(in srgb,var(--surface) 80%,transparent);backdrop-filter:saturate(1.4) blur(14px);border-bottom:1px solid var(--line)}
.topbar .wrap{display:flex;align-items:center;justify-content:space-between;height:64px}
.logo{font-weight:800;font-size:20px;letter-spacing:-.04em}
.logo .dot{color:var(--purple)}
.topbar .actions{display:flex;align-items:center;gap:10px}

/* ---------- hero (guest) ---------- */
.hero{text-align:center;padding:72px 0 40px}
.hero h1{font-size:clamp(32px,5vw,52px);font-weight:800;letter-spacing:-.035em;line-height:1.05;max-width:14ch;margin:0 auto 18px}
.hero h1 em{font-style:normal;color:var(--purple)}
.hero p{font-size:18px;color:var(--text-2);max-width:560px;margin:0 auto 26px}
.section-h{display:flex;align-items:baseline;justify-content:space-between;margin:8px 0 16px}
.section-h h2{font-size:20px;font-weight:700;letter-spacing:-.02em}
.section-h .more{font-size:13px;color:var(--text-2)}

/* ---------- grids ---------- */
.grid{display:grid;gap:18px}
.grid.c3{grid-template-columns:repeat(3,1fr)}
.grid.c4{grid-template-columns:repeat(4,1fr)}
.grid.c2{grid-template-columns:repeat(2,1fr)}

/* ---------- generic card ---------- */
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);box-shadow:var(--shadow-sm)}
.card.pad{padding:22px}

/* ---------- course card (guest catalog) ---------- */
.course{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);box-shadow:var(--shadow-sm);overflow:hidden;display:flex;flex-direction:column;transition:box-shadow .18s,transform .18s}
.course:hover{box-shadow:var(--shadow);transform:translateY(-2px)}
.course .pad{padding:18px;display:flex;flex-direction:column;flex:1}
.course h3{font-size:17px;font-weight:700;letter-spacing:-.01em;margin-bottom:6px}
.course .desc{font-size:13.5px;color:var(--text-2);flex:1}
.course .row{display:flex;align-items:center;justify-content:space-between;margin-top:14px;gap:10px}
.course .price{font-size:18px;font-weight:700}
.course .price s{color:var(--text-3);font-weight:500;font-size:13px;margin-right:6px}

/* ---------- thumbnail (Vimeo-style, dark) ---------- */
.thumb{position:relative;aspect-ratio:16/9;background:#15181C;border-bottom:1px solid var(--line);display:flex;flex-direction:column;justify-content:center;padding:18px 20px;overflow:hidden}
.thumb::before{content:'';position:absolute;left:0;top:0;bottom:0;width:4px;background:var(--orange)}
.thumb .kicker{position:absolute;top:12px;right:14px;font-size:10px;font-weight:700;letter-spacing:.04em;color:#C9CDD2;background:rgba(255,255,255,.08);padding:3px 8px;border-radius:var(--r-pill)}
.thumb .num{font-size:30px;font-weight:800;color:#fff;letter-spacing:-.03em;line-height:1}
.thumb .ttl{font-size:18px;font-weight:700;color:#fff;margin-top:4px;letter-spacing:-.02em}
.thumb .wm{position:absolute;bottom:12px;left:20px;font-size:10px;color:rgba(255,255,255,.34);letter-spacing:.02em}
.thumb .dur{position:absolute;bottom:10px;right:12px;font-size:11px;font-weight:600;color:#fff;background:rgba(0,0,0,.6);padding:3px 7px;border-radius:var(--r-xs)}
.thumb.locked::after{content:'🔒';position:absolute;inset:0;display:flex;align-items:center;justify-content:center;font-size:26px;background:rgba(10,12,14,.55)}

/* ---------- app shell (dashboard) ---------- */
.app{display:grid;grid-template-columns:var(--sidebar-w) 1fr;min-height:100vh}
.sidebar{position:sticky;top:0;align-self:start;height:100vh;background:var(--surface);border-right:1px solid var(--line);display:flex;flex-direction:column;padding:18px 14px;gap:4px}
.sidebar .logo{padding:6px 10px 14px}
.nav-i{display:flex;align-items:center;gap:12px;padding:10px 12px;border-radius:10px;font-size:14px;font-weight:600;color:var(--text-2);cursor:pointer;border:none;background:transparent;width:100%;text-align:left;font-family:inherit}
.nav-i:hover{background:var(--surface-2);color:var(--text)}
.nav-i.on{background:var(--surface-2);color:var(--text)}
.nav-i .ic{width:20px;text-align:center;font-size:16px}
.sidebar .spacer{flex:1}
.side-card{background:var(--surface-2);border-radius:var(--r);padding:14px;margin-top:8px}
.side-card .t{font-size:13px;font-weight:700;margin-bottom:8px}
.main{min-width:0;display:flex;flex-direction:column}
.appbar{position:sticky;top:0;z-index:20;background:color-mix(in srgb,var(--surface) 82%,transparent);backdrop-filter:blur(12px);border-bottom:1px solid var(--line);height:64px;display:flex;align-items:center;gap:14px;padding:0 28px}
.appbar .greet{font-size:14px;font-weight:600;color:var(--text-2)}
.appbar .right{margin-left:auto;display:flex;align-items:center;gap:12px}
.avatar{width:34px;height:34px;border-radius:50%;background:linear-gradient(135deg,var(--purple),#5B43EF);color:#fff;display:flex;align-items:center;justify-content:center;font-size:14px;font-weight:700}
.content{padding:26px 28px 60px;max-width:1120px}
.page-title{font-size:24px;font-weight:800;letter-spacing:-.03em;margin-bottom:4px}
.page-sub{color:var(--text-2);font-size:14px;margin-bottom:22px}
.h-row{display:flex;align-items:baseline;justify-content:space-between;margin:26px 0 14px}
.h-row h2{font-size:16px;font-weight:700;letter-spacing:-.01em}

/* ---------- course hero (dashboard home) ---------- */
.chero{display:flex;gap:22px;align-items:center;padding:20px;flex-wrap:wrap}
.chero .thumb{flex:0 0 280px;aspect-ratio:16/9;border-radius:var(--r-sm);border:none;cursor:pointer}
.chero .info{flex:1;min-width:240px}
.chero h3{font-size:20px;font-weight:800;letter-spacing:-.02em}
.chero .meta{font-size:13px;color:var(--text-2);margin-top:2px}
.prog{height:8px;background:var(--surface-2);border-radius:var(--r-pill);overflow:hidden;margin:14px 0 8px}
.prog>div{height:100%;background:var(--purple);border-radius:var(--r-pill);transition:width .5s}
.prog-l{font-size:12.5px;color:var(--text-2)}
.chero .cta{display:flex;gap:10px;margin-top:16px;flex-wrap:wrap}

/* lecture card */
.lcard{cursor:pointer;border:1px solid var(--line);border-radius:var(--r);overflow:hidden;background:var(--surface);box-shadow:var(--shadow-sm);transition:box-shadow .18s,transform .18s}
.lcard:hover{box-shadow:var(--shadow);transform:translateY(-2px)}
.lcard .thumb{aspect-ratio:16/9;border-bottom:none;border-radius:0}
.lcard .pad{padding:12px 14px}
.lcard .lt{font-size:14px;font-weight:600;letter-spacing:-.01em}
.lcard .lm{font-size:12px;color:var(--text-3);margin-top:3px}

/* ---------- workbook table of contents (course = workbook) ---------- */
.toc{padding:4px 0}
.toc-row{display:flex;align-items:center;gap:14px;padding:13px 18px;border-bottom:1px solid var(--line);cursor:pointer;transition:background .12s}
.toc-row:last-child{border-bottom:none}
.toc-row:hover{background:var(--surface-2)}
.toc-row.current{background:color-mix(in srgb,var(--purple) 7%,transparent)}
.toc-row .tnum{width:30px;height:30px;border-radius:8px;background:var(--surface-2);display:flex;align-items:center;justify-content:center;font-size:12.5px;font-weight:700;color:var(--text-2);flex:0 0 auto}
.toc-row.done .tnum{background:color-mix(in srgb,var(--green) 16%,transparent);color:var(--green)}
.toc-row.current .tnum{background:var(--ink);color:var(--ink-on)}
.toc-row .tt{font-size:14px;font-weight:600;letter-spacing:-.01em}
.toc-row .now{margin-left:auto;font-size:11px;font-weight:700;color:var(--purple)}
.toc-row .chev{margin-left:auto;color:var(--text-3);font-size:15px}

/* quick action card */
.qcard{display:flex;align-items:center;gap:14px;padding:16px;background:var(--surface);border:1px solid var(--line);border-radius:var(--r);box-shadow:var(--shadow-sm);cursor:pointer;transition:background .15s}
.qcard:hover{background:var(--surface-2)}
.qcard .qic{width:42px;height:42px;border-radius:10px;background:var(--surface-2);display:flex;align-items:center;justify-content:center;font-size:20px;flex:0 0 auto}
.qcard .qt{font-size:14px;font-weight:700}
.qcard .qs{font-size:12px;color:var(--text-2)}

/* ---------- links list ---------- */
.links{display:flex;flex-direction:column}
.lnk{display:flex;align-items:center;gap:14px;padding:15px 8px;border-bottom:1px solid var(--line)}
.lnk:last-child{border-bottom:none}
.lnk:hover{background:var(--surface-2);border-radius:10px}
.lnk .ic{width:26px;text-align:center;font-size:19px}
.lnk .t{font-size:14.5px;font-weight:600}.lnk .h{font-size:12.5px;color:var(--text-2)}
.lnk .ar{margin-left:auto;color:var(--text-3)}

/* ---------- profile ---------- */
.pf{display:flex;align-items:center;gap:16px;margin-bottom:8px}
.pf .av{width:60px;height:60px;border-radius:50%;background:linear-gradient(135deg,var(--purple),#5B43EF);color:#fff;display:flex;align-items:center;justify-content:center;font-size:24px;font-weight:700}
.kv{display:flex;justify-content:space-between;gap:14px;font-size:14px;padding:13px 0;border-top:1px solid var(--line)}
.kv .k{color:var(--text-2)}

/* ---------- auth (login.html) ---------- */
.auth{min-height:100vh;display:flex;align-items:center;justify-content:center;padding:24px}
.auth-card{width:min(400px,100%);background:var(--surface);border:1px solid var(--line);border-radius:18px;box-shadow:var(--shadow-lg);padding:34px 30px}
.auth-card .logo{text-align:center;margin-bottom:18px;display:block}
.auth-card h1{font-size:21px;font-weight:800;letter-spacing:-.02em;text-align:center;margin-bottom:6px}
.auth-card p{font-size:13.5px;color:var(--text-2);text-align:center;margin-bottom:20px;line-height:1.5}
.field{width:100%;height:48px;border:1px solid var(--line-2);border-radius:var(--r);background:var(--bg);padding:0 16px;font-family:inherit;font-size:16px;color:var(--text);outline:none;transition:border-color .15s,box-shadow .15s}
.field:focus{border-color:var(--purple);box-shadow:0 0 0 3px color-mix(in srgb,var(--purple) 22%,transparent)}
.field.code{text-align:center;letter-spacing:10px;font-size:24px;font-weight:700;padding:0}
.auth-err{color:#E5484D;font-size:13px;min-height:18px;margin-top:8px;text-align:center}
.auth-foot{text-align:center;margin-top:16px;font-size:12.5px;color:var(--text-3)}
.auth-foot a{color:var(--blue)}
.linkbtn{background:none;border:none;color:var(--text-2);font-family:inherit;font-size:13px;cursor:pointer;text-decoration:underline;margin-top:14px}

.foot{padding:30px 0;text-align:center;font-size:12.5px;color:var(--text-3)}

/* ---------- responsive ---------- */
@media(max-width:900px){
  .grid.c3,.grid.c4{grid-template-columns:repeat(2,1fr)}
  .app{grid-template-columns:1fr}
  .sidebar{position:fixed;left:0;top:0;bottom:0;width:240px;transform:translateX(-100%);transition:transform .25s;z-index:60;box-shadow:var(--shadow-lg)}
  .sidebar.open{transform:none}
  .menu-btn{display:inline-flex!important}
  .scrim{position:fixed;inset:0;background:rgba(0,0,0,.4);z-index:55}
}
@media(min-width:901px){.menu-btn{display:none}}
@media(max-width:600px){
  .grid.c3,.grid.c4,.grid.c2{grid-template-columns:1fr}
  .hero{padding:48px 0 28px}
}
.menu-btn{display:none}