/* ============================================================
   Manuscript — Music ATAR Theory Trainer
   Visual language: Resend-style dark UI — near-black grounds,
   hairline borders, Inter + JetBrains Mono, white primary action.
   ============================================================ */

:root{
  --bg:#0a0a0a;
  --bg-1:#0f0f0f;
  --bg-2:#141414;
  --bg-3:#1a1a1a;
  --border:#242424;
  --border-strong:#333333;
  --text:#fafafa;
  --text-2:#a1a1a1;
  --text-3:#6e6e6e;
  --white:#ffffff;
  --success:#3ecf8e;
  --success-dim:rgba(62,207,142,.14);
  --danger:#f0736a;
  --danger-dim:rgba(240,115,106,.13);
  --accent:#7c8cff;
  --radius:8px;
  --radius-lg:12px;
  --radius-xl:16px;
  --font:"Inter",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  --mono:"JetBrains Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --sidebar-w:248px;
  --shadow:0 1px 2px rgba(0,0,0,.4),0 8px 32px rgba(0,0,0,.24);
}

*{box-sizing:border-box;margin:0;padding:0}
html{-webkit-text-size-adjust:100%}
body{
  background:var(--bg);
  color:var(--text);
  font-family:var(--font);
  font-size:15px;
  line-height:1.6;
  letter-spacing:-0.011em;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
body::before{
  content:"";position:fixed;inset:0;pointer-events:none;z-index:0;
  background:radial-gradient(680px 380px at 72% -8%,rgba(124,140,255,.10),transparent 70%);
}
a{color:inherit;text-decoration:none}
button{font-family:inherit;cursor:pointer;color:inherit;background:none;border:none}
select{font-family:inherit}
:focus-visible{outline:2px solid var(--accent);outline-offset:2px;border-radius:4px}
::selection{background:rgba(124,140,255,.32)}
@media (prefers-reduced-motion:reduce){*{animation-duration:.001ms!important;transition-duration:.001ms!important}}

/* ---------------- layout ---------------- */
.layout{display:grid;grid-template-columns:var(--sidebar-w) 1fr;min-height:100vh;position:relative;z-index:1}

.sidebar{border-right:1px solid var(--border);background:var(--bg);position:sticky;top:0;height:100vh}
.sidebar-inner{display:flex;flex-direction:column;height:100%;padding:18px 14px 16px}

.brand{display:flex;align-items:center;gap:9px;padding:8px 8px 18px}
.brand-mark{
  display:grid;place-items:center;width:26px;height:26px;border-radius:7px;
  background:var(--white);color:#0a0a0a;font-size:15px;line-height:1;
}
.brand-text{font-weight:600;font-size:15px;letter-spacing:-0.02em}
.brand-badge{
  margin-left:auto;font-family:var(--mono);font-size:10px;letter-spacing:.08em;
  color:var(--text-3);border:1px solid var(--border);border-radius:5px;padding:2px 6px;
}

.nav{display:flex;flex-direction:column;gap:1px;overflow-y:auto;flex:1;margin:0 -4px;padding:0 4px}
.nav-label{
  font-family:var(--mono);font-size:10.5px;letter-spacing:.12em;text-transform:uppercase;
  color:var(--text-3);padding:16px 8px 7px;
}
.nav-item{
  display:flex;align-items:center;gap:9px;width:100%;text-align:left;
  padding:7px 8px;border-radius:6px;font-size:13.5px;color:var(--text-2);
  transition:background .13s ease,color .13s ease;line-height:1.35;
}
.nav-item:hover{background:var(--bg-2);color:var(--text)}
.nav-item.active{background:var(--bg-3);color:var(--text)}
.nav-glyph{font-size:8px;color:var(--text-3);width:12px;text-align:center}
.nav-item.active .nav-glyph{color:var(--accent)}
.nav-item .nav-num{font-family:var(--mono);font-size:10.5px;color:var(--text-3);width:14px}
.nav-item .nav-dot{margin-left:auto;width:6px;height:6px;border-radius:50%;background:var(--border-strong);flex:none}
.nav-item .nav-dot.part{background:var(--accent)}
.nav-item .nav-dot.done{background:var(--success)}

.sidebar-foot{border-top:1px solid var(--border);padding-top:14px;margin-top:10px;display:flex;flex-direction:column;gap:8px}
.foot-stats{display:flex;gap:14px;font-family:var(--mono);font-size:11px;color:var(--text-2)}
.foot-stats b{color:var(--text);font-weight:500}
.link-muted{font-size:12px;color:var(--text-3);text-align:left;width:max-content;transition:color .13s}
.link-muted:hover{color:var(--danger)}
.foot-note{font-size:11px;color:var(--text-3);line-height:1.45}

.shell{min-width:0;display:flex;flex-direction:column}
.topbar{
  position:sticky;top:0;z-index:20;display:flex;align-items:center;gap:12px;
  height:52px;padding:0 clamp(16px,4vw,40px);
  background:rgba(10,10,10,.72);backdrop-filter:blur(10px);
  border-bottom:1px solid var(--border);
}
.icon-btn{display:none;font-size:16px;color:var(--text-2);padding:6px;border-radius:6px}
.icon-btn:hover{background:var(--bg-2);color:var(--text)}
.topbar-title{font-size:13px;font-weight:500;color:var(--text-2)}
.topbar-src{margin-left:auto;font-family:var(--mono);font-size:11.5px;color:var(--text-3);transition:color .13s}
.topbar-src:hover{color:var(--text)}

.content{padding:clamp(28px,5vw,52px) clamp(16px,4vw,40px) 120px;max-width:840px;width:100%}
.view{animation:fade .32s ease}
@keyframes fade{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}

/* ---------------- typography ---------------- */
.eyebrow{
  font-family:var(--mono);font-size:11px;letter-spacing:.13em;text-transform:uppercase;
  color:var(--accent);margin-bottom:14px;display:flex;align-items:center;gap:8px;
}
h1{font-size:clamp(24px,4vw,30px);font-weight:600;letter-spacing:-0.03em;line-height:1.15;text-wrap:balance;margin-bottom:12px}
h2.sec{font-size:18px;font-weight:600;letter-spacing:-0.02em;margin-bottom:4px}
.subtitle{font-size:15.5px;color:var(--text-2);max-width:62ch;margin-bottom:34px;line-height:1.62}
.divider{height:1px;background:var(--border);margin:38px 0}

/* ---------------- buttons ---------------- */
.btn{
  display:inline-flex;align-items:center;gap:7px;
  font-size:13px;font-weight:500;letter-spacing:-0.01em;
  padding:8px 14px;border-radius:var(--radius);transition:background .13s,border-color .13s,opacity .13s;
  border:1px solid transparent;white-space:nowrap;
}
.btn-primary{background:var(--white);color:#0a0a0a}
.btn-primary:hover{opacity:.86}
.btn-ghost{border-color:var(--border);color:var(--text-2)}
.btn-ghost:hover{border-color:var(--border-strong);color:var(--text)}
.btn-row{display:flex;gap:10px;flex-wrap:wrap}

/* ---------------- overview ---------------- */
.hero-grid{display:grid;grid-template-columns:auto 1fr;gap:28px;align-items:center;margin-bottom:8px}
.ring{position:relative;width:116px;height:116px;border-radius:50%;flex:none;
  background:conic-gradient(var(--white) calc(var(--v,0)*1%),var(--bg-3) 0);transition:background .8s ease}
.ring::after{content:"";position:absolute;inset:7px;border-radius:50%;background:var(--bg)}
.ring span{position:relative;z-index:1;display:grid;place-items:center;height:100%;font-size:24px;font-weight:600;letter-spacing:-0.03em}
.hero-copy h1{margin-bottom:6px}
.hero-copy p{color:var(--text-2);font-size:14px}

.tiles{display:grid;grid-template-columns:repeat(4,1fr);gap:10px;margin:26px 0 8px}
.tile{border:1px solid var(--border);border-radius:var(--radius-lg);background:var(--bg-1);padding:14px 15px}
.tile .t-label{font-family:var(--mono);font-size:10.5px;letter-spacing:.06em;text-transform:uppercase;color:var(--text-3);margin-bottom:7px}
.tile .t-value{font-size:22px;font-weight:600;letter-spacing:-0.03em;font-variant-numeric:tabular-nums}
.tile .t-value small{font-size:13px;color:var(--text-3);font-weight:400}

/* module rows */
.rows{border:1px solid var(--border);border-radius:var(--radius-lg);overflow:hidden;background:var(--bg-1)}
.row{
  display:grid;grid-template-columns:26px 1fr auto;gap:14px;align-items:center;
  width:100%;text-align:left;padding:15px 16px;border-top:1px solid var(--border);
  transition:background .12s ease;
}
.row:first-child{border-top:none}
.row:hover{background:var(--bg-2)}
.row .r-num{font-family:var(--mono);font-size:11px;color:var(--text-3)}
.row .r-title{font-size:14px;font-weight:500;letter-spacing:-0.01em}
.row .r-meta{font-family:var(--mono);font-size:11px;color:var(--text-3);margin-top:2px}
.row .r-right{display:flex;align-items:center;gap:14px}
.row .r-check{font-size:11px;color:var(--success);font-family:var(--mono)}
.mini-bar{width:96px;height:4px;border-radius:3px;background:var(--bg-3);overflow:hidden}
.mini-bar i{display:block;height:100%;background:var(--white);border-radius:3px;transition:width .5s ease}
.row .chev{color:var(--text-3);font-size:12px}

/* ---------------- lessons / prose ---------------- */
.card{border:1px solid var(--border);border-radius:var(--radius-lg);background:var(--bg-1);padding:20px 22px;margin-bottom:12px}
.card h3{font-size:15.5px;font-weight:600;letter-spacing:-0.02em;margin-bottom:10px;display:flex;align-items:center;gap:10px}
.card h3 .n{
  font-family:var(--mono);font-size:10.5px;color:var(--text-2);
  border:1px solid var(--border);border-radius:5px;padding:2px 6px;flex:none;
}
.prose p{margin:9px 0;color:var(--text-2)}
.prose p:first-child{margin-top:0}
.prose ul,.prose ol{margin:9px 0 9px 20px;color:var(--text-2)}
.prose li{margin:4px 0}
.prose b,.prose .term{color:var(--text);font-weight:600}
.prose code,.gly{
  font-family:var(--mono);font-size:.86em;background:var(--bg-3);border:1px solid var(--border);
  border-radius:5px;padding:1px 5px;color:var(--text);
}
.callout{
  border:1px solid var(--border);border-left:2px solid var(--accent);
  background:var(--bg-2);border-radius:0 8px 8px 0;padding:10px 14px;margin:14px 0;
  font-size:13.5px;color:var(--text-2);
}
.callout b{color:var(--text)}

.scroll-x{overflow-x:auto;margin:12px 0;border:1px solid var(--border);border-radius:8px}
table.tbl{width:100%;border-collapse:collapse;font-size:13px}
table.tbl th,table.tbl td{padding:8px 12px;text-align:left;border-bottom:1px solid var(--border);color:var(--text-2)}
table.tbl tr:last-child td{border-bottom:none}
table.tbl th{
  background:var(--bg-2);color:var(--text-3);font-family:var(--mono);font-weight:500;
  font-size:10.5px;letter-spacing:.05em;text-transform:uppercase;white-space:nowrap;
}
table.tbl td b,table.tbl td .term{color:var(--text)}

.mark-btn{
  display:inline-flex;align-items:center;gap:7px;margin-top:16px;
  font-size:12.5px;font-weight:500;padding:7px 13px;border-radius:var(--radius);
  border:1px solid var(--border);color:var(--text-2);transition:border-color .13s,color .13s,background .13s;
}
.mark-btn:hover{border-color:var(--border-strong);color:var(--text)}
.mark-btn.done{border-color:var(--success);color:var(--success);background:var(--success-dim)}

/* ---------------- quiz ---------------- */
.q{border:1px solid var(--border);border-radius:var(--radius-lg);background:var(--bg-1);padding:18px 20px;margin-bottom:12px}
.q-head{font-family:var(--mono);font-size:10.5px;letter-spacing:.05em;text-transform:uppercase;color:var(--text-3);margin-bottom:9px;display:flex;gap:8px;align-items:center}
.q-head .ok{color:var(--success)}
.q-text{font-size:14.5px;margin-bottom:13px;color:var(--text);letter-spacing:-0.01em}
.choice{
  display:flex;gap:10px;width:100%;text-align:left;align-items:baseline;
  border:1px solid var(--border);border-radius:8px;padding:10px 13px;margin:7px 0;
  font-size:13.5px;color:var(--text-2);transition:border-color .12s,background .12s,color .12s;
}
.choice:hover:not(:disabled){border-color:var(--border-strong);color:var(--text)}
.choice:disabled{cursor:default}
.choice .key{font-family:var(--mono);font-size:11px;color:var(--text-3);flex:none;width:12px}
.choice.correct{border-color:var(--success);background:var(--success-dim);color:var(--text)}
.choice.correct .key{color:var(--success)}
.choice.wrong{border-color:var(--danger);background:var(--danger-dim);color:var(--text)}
.choice.wrong .key{color:var(--danger)}
.choice.chosen{border-color:var(--border-strong);background:var(--bg-2);color:var(--text)}
.rationale{margin-top:12px;padding-top:11px;border-top:1px solid var(--border);font-size:13px;color:var(--text-2)}
.rationale b{color:var(--success);font-weight:600}

/* ---------------- flashcards ---------------- */
.deck-controls{display:flex;align-items:center;gap:10px;margin-bottom:22px;flex-wrap:wrap}
.select{
  font-size:13px;padding:7px 11px;border:1px solid var(--border);border-radius:var(--radius);
  background:var(--bg-1);color:var(--text);transition:border-color .13s;
}
.select:hover{border-color:var(--border-strong)}
.deck-wrap{display:flex;flex-direction:column;align-items:center;gap:18px}
.deck-meta{font-family:var(--mono);font-size:11px;color:var(--text-3)}
.flash{width:min(480px,100%);min-height:236px;perspective:1500px;cursor:pointer}
.flash-inner{position:relative;width:100%;min-height:236px;transition:transform .5s ease;transform-style:preserve-3d}
.flash.flipped .flash-inner{transform:rotateY(180deg)}
.face{
  position:absolute;inset:0;backface-visibility:hidden;display:grid;place-items:center;text-align:center;
  border:1px solid var(--border);border-radius:var(--radius-xl);background:var(--bg-1);padding:34px 30px;
}
.face.back{transform:rotateY(180deg);background:var(--bg-2)}
.face .lbl{position:absolute;top:14px;left:16px;font-family:var(--mono);font-size:10px;letter-spacing:.12em;text-transform:uppercase;color:var(--text-3)}
.face .term{font-size:20px;font-weight:600;letter-spacing:-0.02em}
.face .def{font-size:14.5px;color:var(--text-2);line-height:1.6}
.rate{display:flex;gap:9px}
.rate button{font-size:12.5px;font-weight:500;padding:8px 16px;border-radius:var(--radius);border:1px solid var(--border);color:var(--text-2);transition:border-color .13s,color .13s,background .13s}
.rate .again:hover{border-color:var(--danger);color:var(--danger);background:var(--danger-dim)}
.rate .good:hover{border-color:var(--accent);color:var(--text)}
.rate .easy:hover{border-color:var(--success);color:var(--success);background:var(--success-dim)}
.deck-done{border:1px solid var(--border);border-radius:var(--radius-xl);background:var(--bg-1);padding:34px;text-align:center;width:min(480px,100%)}
.deck-done .term{font-size:18px;font-weight:600;margin-bottom:6px}
.deck-done p{color:var(--text-2);font-size:13.5px;margin-bottom:16px}

/* ---------------- exam ---------------- */
.exam-bar{
  position:sticky;top:52px;z-index:15;display:flex;justify-content:space-between;align-items:center;
  padding:12px 0;margin-bottom:18px;background:var(--bg);border-bottom:1px solid var(--border);
}
.exam-bar strong{font-size:14px;font-weight:600;letter-spacing:-0.02em}
.exam-progress{font-family:var(--mono);font-size:11px;color:var(--text-3)}
.result-big{font-size:clamp(26px,5vw,34px);font-weight:600;letter-spacing:-0.03em;font-variant-numeric:tabular-nums;margin-bottom:10px}

/* ---------------- toast + scrim ---------------- */
.toast{
  position:fixed;left:50%;bottom:24px;transform:translateX(-50%) translateY(150%);
  background:var(--bg-3);border:1px solid var(--border-strong);color:var(--text);
  font-size:13px;font-weight:500;padding:10px 16px;border-radius:var(--radius);
  box-shadow:var(--shadow);z-index:60;transition:transform .32s ease;
}
.toast.show{transform:translateX(-50%) translateY(0)}
.toast .xp{font-family:var(--mono);color:var(--success);margin-left:8px}
.scrim{position:fixed;inset:0;background:rgba(0,0,0,.5);z-index:29;opacity:0;pointer-events:none;transition:opacity .2s}
.scrim.show{opacity:1;pointer-events:auto}

/* ---------------- responsive ---------------- */
@media (max-width:900px){
  .tiles{grid-template-columns:repeat(2,1fr)}
}
@media (max-width:820px){
  .layout{grid-template-columns:1fr}
  .sidebar{
    position:fixed;left:0;top:0;height:100dvh;width:var(--sidebar-w);z-index:30;
    transform:translateX(-100%);transition:transform .24s ease;
  }
  .sidebar.open{transform:none}
  .icon-btn{display:block}
  .hero-grid{grid-template-columns:1fr;justify-items:start;gap:18px}
}
@media (max-width:560px){
  .tiles{grid-template-columns:1fr 1fr}
  .row{grid-template-columns:22px 1fr;gap:10px}
  .row .r-right{grid-column:2;justify-content:flex-start;margin-top:8px}
  .mini-bar{width:120px}
}