/* =========================================================
   SQL Mentoring — shared design system (dark "tech" theme)
   Used by every topic page. Edit here → applies everywhere.
   ========================================================= */
:root{
  --bg:#080B12; --bg-2:#0C111C; --panel:rgba(255,255,255,.035);
  --panel-2:rgba(255,255,255,.06); --border:rgba(255,255,255,.09); --border-2:rgba(255,255,255,.16);
  --text:#EAF0F7; --muted:#93A1B5; --faint:#5b6b80;
  --accent:#22D3EE; --accent-2:#A78BFA; --accent-3:#F472B6;
  --ok:#34D399; --warn:#FBBF24; --bad:#F87171;
  --font:ui-sans-serif,system-ui,-apple-system,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  --mono:ui-monospace,"SF Mono","JetBrains Mono","Fira Code",Menlo,Consolas,monospace;
  --nav-h:60px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:calc(var(--nav-h) + 14px)}
body{
  margin:0;color:var(--text);font-family:var(--font);font-size:16px;line-height:1.65;
  -webkit-font-smoothing:antialiased;
  background:
    radial-gradient(1200px 700px at 85% -8%, rgba(34,211,238,.10), transparent 60%),
    radial-gradient(1000px 640px at -8% 8%, rgba(167,139,250,.10), transparent 55%),
    radial-gradient(900px 700px at 50% 108%, rgba(244,114,182,.07), transparent 60%),
    var(--bg);
}
body::before{content:"";position:fixed;inset:0;z-index:0;pointer-events:none;
  background-image:radial-gradient(rgba(255,255,255,.035) 1px,transparent 1px);background-size:38px 38px;
  mask-image:radial-gradient(circle at 50% 0%,#000,transparent 80%)}
a{color:inherit;text-decoration:none}
::selection{background:rgba(34,211,238,.3)}

/* ---------- scroll progress + top nav ---------- */
.scrollbar{position:fixed;top:0;left:0;height:3px;width:0;z-index:60;background:linear-gradient(90deg,var(--accent),var(--accent-2),var(--accent-3));box-shadow:0 0 12px rgba(34,211,238,.6)}
nav.top{position:fixed;top:0;left:0;right:0;height:var(--nav-h);z-index:50;display:flex;align-items:center;gap:16px;
  padding:0 clamp(14px,4vw,34px);background:rgba(8,11,18,.72);backdrop-filter:blur(14px);border-bottom:1px solid var(--border)}
.logo{display:flex;align-items:center;gap:9px;font-weight:800;letter-spacing:-.01em;white-space:nowrap;font-size:.98rem;color:var(--text)}
.logo .g{width:26px;height:26px;border-radius:8px;background:linear-gradient(135deg,var(--accent),var(--accent-2));display:grid;place-items:center;font-size:.9rem;box-shadow:0 4px 16px rgba(34,211,238,.35)}
.crumb{font-family:var(--mono);font-size:.76rem;color:var(--muted);white-space:nowrap}
.topnav{display:flex;gap:6px;margin-left:auto;align-items:center}
.topnav a{font-size:.82rem;color:var(--muted);padding:7px 12px;border-radius:9px;white-space:nowrap;transition:color .15s,background .15s;border:1px solid transparent}
.topnav a:hover{color:var(--text);background:var(--panel-2)}
.topnav a.disabled{opacity:.3;pointer-events:none}
.topnav a.all{border-color:var(--border)}
@media (max-width:680px){.crumb{display:none}}

/* ---------- layout ---------- */
.container{width:100%;max-width:1080px;margin:0 auto;padding:0 clamp(18px,5vw,32px)}
section{position:relative;z-index:1;padding:clamp(56px,8vw,96px) 0;border-bottom:1px solid rgba(255,255,255,.045)}
.eyebrow{font-family:var(--mono);font-size:.74rem;letter-spacing:.2em;text-transform:uppercase;color:var(--accent);display:inline-flex;align-items:center;gap:9px;margin:0 0 16px}
.eyebrow::before{content:"";width:22px;height:1px;background:linear-gradient(90deg,var(--accent),transparent)}
h1{font-size:clamp(2.3rem,6vw,4.2rem);line-height:1.03;margin:0 0 18px;font-weight:850;letter-spacing:-.03em;text-wrap:balance}
h2{font-size:clamp(1.7rem,3.8vw,2.7rem);line-height:1.08;margin:0 0 16px;font-weight:800;letter-spacing:-.02em;text-wrap:balance}
h3{font-size:1.12rem;margin:0 0 8px;font-weight:700}
.lead{font-size:clamp(1.02rem,1.5vw,1.18rem);color:var(--muted);max-width:66ch;margin:0 0 8px}
p{color:var(--muted);max-width:68ch}
.grad{background:linear-gradient(100deg,var(--accent),var(--accent-2) 55%,var(--accent-3));-webkit-background-clip:text;background-clip:text;color:transparent}
.mono{font-family:var(--mono)}

/* ---------- reveal on scroll ---------- */
.rv{opacity:0;transform:translateY(26px);transition:opacity .7s cubic-bezier(.2,.7,.2,1),transform .7s cubic-bezier(.2,.7,.2,1)}
.rv.in{opacity:1;transform:none}
.rv.d1{transition-delay:.08s}.rv.d2{transition-delay:.16s}.rv.d3{transition-delay:.24s}.rv.d4{transition-delay:.32s}.rv.d5{transition-delay:.4s}

/* ---------- cards / grid / split ---------- */
.card{background:var(--panel);backdrop-filter:blur(10px);border:1px solid var(--border);border-radius:18px;padding:22px;transition:transform .25s,border-color .25s,background .25s}
.card:hover{transform:translateY(-4px);border-color:var(--border-2);background:var(--panel-2)}
.grid{display:grid;gap:16px}
.g2{grid-template-columns:repeat(2,1fr)}.g3{grid-template-columns:repeat(3,1fr)}
.g4{grid-template-columns:repeat(auto-fit,minmax(180px,1fr))}
@media (max-width:820px){.g2,.g3{grid-template-columns:1fr}}
.split{display:grid;grid-template-columns:1.05fr 1fr;gap:32px;align-items:center}
.split.top{align-items:start}
@media (max-width:860px){.split{grid-template-columns:1fr;gap:24px}}

/* ---------- SQL block ---------- */
.sql{font-family:var(--mono);font-size:.9rem;line-height:1.7;background:linear-gradient(180deg,#0d1420,#0a0f18);border:1px solid var(--border-2);border-radius:14px;overflow:hidden;box-shadow:0 24px 60px -34px rgba(0,0,0,.8)}
.sql .bar{display:flex;gap:6px;align-items:center;padding:10px 13px;border-bottom:1px solid var(--border)}
.sql .bar i{width:11px;height:11px;border-radius:50%}
.sql .bar .r{background:#ff5f57}.sql .bar .y{background:#febc2e}.sql .bar .gg{background:#28c840}
.sql .bar span{margin-left:8px;font-size:.72rem;color:var(--faint)}
.sql pre{margin:0;padding:16px 18px;white-space:pre-wrap;overflow-x:auto}
.k{color:var(--accent-2);font-weight:600}.fn{color:var(--accent)}.str{color:#7ee787}.num{color:#f0883e}.com{color:var(--faint);font-style:italic}
/* line-by-line execution highlight (reusable) */
.sql .line{display:block;padding:1px 6px;margin:0 -6px;border-radius:5px;transition:background .3s,opacity .3s;opacity:.55}
.sql .line.active{opacity:1;background:rgba(34,211,238,.14)}
.sql .line.rb.active{background:rgba(251,191,36,.16)}

/* ---------- badges + callouts ---------- */
.badge{display:inline-flex;align-items:center;gap:7px;font-family:var(--mono);font-size:.74rem;padding:5px 11px;border-radius:999px;font-weight:600}
.badge.seq{background:rgba(248,113,113,.14);color:var(--bad);border:1px solid rgba(248,113,113,.3)}
.badge.idx{background:rgba(52,211,153,.14);color:var(--ok);border:1px solid rgba(52,211,153,.3)}
.badge.neutral{background:var(--panel-2);color:var(--muted);border:1px solid var(--border)}
.callout{border-radius:13px;padding:13px 16px;font-size:.9rem;border:1px solid var(--border);display:flex;gap:11px;align-items:flex-start}
.callout .lbl{font-family:var(--mono);font-size:.66rem;letter-spacing:.08em;text-transform:uppercase;font-weight:700;flex-shrink:0;padding-top:2px}
.callout p{margin:0;color:#c5d1e0}
.callout code{font-family:var(--mono);font-size:.85em;background:var(--panel-2);padding:1px 5px;border-radius:5px}
.callout.analogy{background:rgba(34,211,238,.06);border-color:rgba(34,211,238,.22)} .callout.analogy .lbl{color:var(--accent)}
.callout.mistake{background:rgba(248,113,113,.06);border-color:rgba(248,113,113,.22)} .callout.mistake .lbl{color:var(--bad)}
.callout.tip{background:rgba(167,139,250,.06);border-color:rgba(167,139,250,.22)} .callout.tip .lbl{color:var(--accent-2)}
.note-row{display:grid;gap:10px;margin-top:18px}

/* ---------- buttons ---------- */
.btn{font-family:var(--font);font-size:.9rem;font-weight:650;color:#04222a;background:linear-gradient(180deg,#26d3ee,#12a7c6);border:none;border-radius:11px;padding:11px 18px;cursor:pointer;transition:filter .15s,transform .1s;box-shadow:0 8px 24px -10px rgba(34,211,238,.6)}
.btn:hover{filter:brightness(1.07)}.btn:active{transform:translateY(1px)}
.btn.ghost{background:var(--panel-2);color:var(--text);border:1px solid var(--border-2);box-shadow:none}
.btn:disabled{opacity:.4;cursor:not-allowed}
.btnrow{display:flex;gap:10px;flex-wrap:wrap;margin-top:16px}
.btn:focus-visible,button:focus-visible,a:focus-visible{outline:2px solid var(--accent);outline-offset:2px}

/* ---------- page hero (per topic) ---------- */
.page-hero{padding-top:calc(var(--nav-h) + 66px);border-bottom:1px solid rgba(255,255,255,.06)}
.page-hero .kicker{display:inline-flex;align-items:center;gap:8px;font-family:var(--mono);font-size:.76rem;color:var(--muted);background:var(--panel);border:1px solid var(--border);border-radius:999px;padding:6px 14px;margin-bottom:22px}
.page-hero .kicker .n{color:var(--accent);font-weight:700}
.outcomes{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:14px;margin-top:38px}
.outcome{display:flex;gap:13px;align-items:flex-start}
.outcome .ck{width:26px;height:26px;border-radius:8px;flex-shrink:0;display:grid;place-items:center;background:rgba(52,211,153,.14);color:var(--ok);border:1px solid rgba(52,211,153,.3);font-weight:800;font-size:.85rem}
.outcome b{color:var(--text);font-size:.95rem;font-weight:650}
.outcome span{display:block;color:var(--muted);font-size:.82rem}

/* ---------- generic flow diagram ---------- */
.flow{display:flex;flex-direction:column;align-items:center;gap:0}
.flow.h{flex-direction:row;flex-wrap:wrap;justify-content:center;gap:0}
.fstep{font-family:var(--mono);font-size:.86rem;padding:12px 18px;border-radius:12px;background:var(--panel);border:1px solid var(--border);color:var(--muted);text-align:center;min-width:170px;opacity:.4;transform:scale(.97);transition:all .4s}
.fstep.lit{opacity:1;transform:scale(1);color:var(--text);border-color:var(--accent);background:rgba(34,211,238,.1);box-shadow:0 0 22px -6px rgba(34,211,238,.5)}
.fstep.good.lit{border-color:var(--ok);background:rgba(52,211,153,.12);box-shadow:0 0 22px -6px rgba(52,211,153,.5)}
.fstep.bad.lit{border-color:var(--bad);background:rgba(248,113,113,.12);box-shadow:0 0 22px -6px rgba(248,113,113,.5)}
.fstep.warn.lit{border-color:var(--warn);background:rgba(251,191,36,.12);box-shadow:0 0 22px -6px rgba(251,191,36,.5)}
.fconn{width:2px;height:22px;background:var(--border-2);opacity:.4;transition:opacity .4s,background .4s}
.fconn.lit{opacity:1;background:linear-gradient(var(--accent),var(--accent-2))}
.fbranch{display:flex;gap:12px;flex-wrap:wrap;justify-content:center}

/* ---------- counters (performance panels) ---------- */
.perf{display:grid;grid-template-columns:1fr 1fr;gap:18px}
@media (max-width:720px){.perf{grid-template-columns:1fr}}
.perf-card{border-radius:18px;padding:26px;border:1px solid var(--border);position:relative;overflow:hidden}
.perf-card.bad{background:linear-gradient(180deg,rgba(248,113,113,.09),transparent);border-color:rgba(248,113,113,.28)}
.perf-card.good{background:linear-gradient(180deg,rgba(52,211,153,.09),transparent);border-color:rgba(52,211,153,.28)}
.perf-card .t{font-family:var(--mono);font-size:.76rem;letter-spacing:.06em;text-transform:uppercase;color:var(--muted);margin-bottom:14px;display:flex;align-items:center;gap:8px}
.metric{margin-bottom:16px}.metric:last-child{margin-bottom:0}
.metric .lab{font-size:.78rem;color:var(--muted)}
.metric .val{font-family:var(--mono);font-size:2.3rem;font-weight:800;letter-spacing:-.02em;line-height:1.1;font-variant-numeric:tabular-nums}
.perf-card.bad .val{color:var(--bad)} .perf-card.good .val{color:var(--ok)}

/* ---------- pager (Prev / Next between topics) ---------- */
.pager{max-width:1080px;margin:0 auto;padding:40px clamp(18px,5vw,32px) 30px;display:grid;grid-template-columns:1fr 1fr;gap:16px}
.pager a{display:flex;flex-direction:column;gap:3px;padding:18px 20px;border-radius:16px;border:1px solid var(--border);background:var(--panel);transition:transform .2s,border-color .2s,background .2s}
.pager a:hover{transform:translateY(-3px);border-color:var(--border-2);background:var(--panel-2)}
.pager .dir{font-family:var(--mono);font-size:.74rem;color:var(--muted);letter-spacing:.04em}
.pager b{color:var(--text);font-size:1.02rem}
.pager .next{text-align:right;align-items:flex-end}
.pager a.empty{visibility:hidden}
@media (max-width:600px){.pager{grid-template-columns:1fr}}
.footer{text-align:center;padding:24px 20px 60px;color:var(--faint);font-size:.85rem}

/* ---------- landing (index.html) ---------- */
.hub-hero{padding-top:calc(var(--nav-h) + 80px);text-align:center}
.hub-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:16px;margin:44px 0 30px}
.tcard{display:flex;flex-direction:column;gap:6px;padding:20px;border-radius:16px;border:1px solid var(--border);background:var(--panel);transition:transform .2s,border-color .2s,background .2s;position:relative;min-height:132px}
.tcard:hover{transform:translateY(-4px);border-color:var(--border-2);background:var(--panel-2)}
.tcard .no{font-family:var(--mono);font-size:.74rem;color:var(--accent)}
.tcard h3{margin:2px 0 0;font-size:1.05rem}
.tcard p{margin:0;font-size:.84rem;color:var(--muted)}
.tcard .tag{position:absolute;top:16px;right:16px;font-family:var(--mono);font-size:.62rem;padding:3px 8px;border-radius:999px}
.tcard .tag.live{background:rgba(52,211,153,.16);color:var(--ok)}
.tcard .tag.soon{background:var(--panel-2);color:var(--faint)}
.tcard.soon{opacity:.55;pointer-events:none}
.bucket-label{font-family:var(--mono);font-size:.72rem;letter-spacing:.14em;text-transform:uppercase;color:var(--faint);margin:26px 0 2px;grid-column:1/-1}

/* ---------- timeline (reusable) ---------- */
.timeline{position:relative;padding-left:34px;margin-top:20px}
.timeline::before{content:"";position:absolute;left:11px;top:6px;bottom:6px;width:2px;background:linear-gradient(var(--accent),var(--accent-2),var(--accent-3))}
.tl-item{position:relative;margin-bottom:20px}
.tl-item .dot{position:absolute;left:-28px;top:3px;width:16px;height:16px;border-radius:50%;background:var(--bg);border:2px solid var(--accent);box-shadow:0 0 0 4px rgba(34,211,238,.12)}
.tl-item b{color:var(--text)}.tl-item p{margin:2px 0 0;font-size:.9rem}

/* ---------- comparison table (reusable) ---------- */
.cmptable{border:1px solid var(--border);border-radius:14px;overflow:hidden;background:var(--panel)}
.cmphead,.cmprow{display:grid;grid-template-columns:1.1fr 1fr 1fr}
.cmphead{background:var(--panel-2);font-family:var(--mono);font-size:.72rem;letter-spacing:.04em;color:var(--muted)}
.cmphead div{padding:12px 14px;border-bottom:1px solid var(--border)}
.cmphead .h-v{color:var(--accent)} .cmphead .h-mv{color:var(--accent-2)}
.cmprow{opacity:0;transform:translateY(10px);transition:opacity .5s,transform .5s}
.cmprow.lit{opacity:1;transform:none}
.cmprow div{padding:12px 14px;border-bottom:1px solid rgba(255,255,255,.05);font-size:.88rem}
.cmprow:last-child div{border-bottom:none}
.cmprow .attr{color:var(--muted);font-family:var(--mono);font-size:.8rem}
.cmprow .good{color:var(--ok)} .cmprow .bad{color:var(--bad)} .cmprow .warn{color:var(--warn)}
@media (max-width:640px){.cmphead,.cmprow{grid-template-columns:1fr}.cmphead div:first-child{display:none}}

/* ---------- AlgoViz step-controller (reusable) ---------- */
.av-explain{min-height:2.7em;text-align:center;color:#cbd6e4;font-size:1rem;max-width:60ch;margin:18px auto 12px;line-height:1.5;transition:opacity .2s}
.av-explain b{color:var(--text)} .av-explain .hot{color:var(--accent)} .av-explain .warn{color:var(--warn)} .av-explain .ok{color:var(--ok)}
.av-bar{display:flex;align-items:center;justify-content:center;gap:8px;flex-wrap:wrap;background:var(--panel);border:1px solid var(--border);border-radius:14px;padding:11px 13px;backdrop-filter:blur(10px)}
.av-btn{font-family:var(--font);font-size:.85rem;font-weight:600;color:var(--text);background:var(--panel-2);border:1px solid var(--border-2);border-radius:10px;height:38px;min-width:38px;padding:0 12px;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;gap:6px;transition:background .15s,transform .1s}
.av-btn:hover{background:#22344f}.av-btn:active{transform:translateY(1px)}
.av-btn.play{background:linear-gradient(180deg,#26d3ee,#12a7c6);border-color:#26c9e6;color:#04222a;min-width:96px}
.av-btn:disabled{opacity:.38;cursor:not-allowed}
.av-btn:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
.av-step{font-family:var(--mono);font-size:.78rem;color:var(--muted);min-width:78px;text-align:center;font-variant-numeric:tabular-nums}
.av-sep{width:1px;height:24px;background:var(--border-2);margin:0 2px}
.av-speed{display:flex;align-items:center;gap:7px;font-family:var(--mono);font-size:.72rem;color:var(--muted)}
.av-speed input[type=range]{width:88px;accent-color:var(--accent)}
.av-toggle{display:inline-flex;align-items:center;gap:6px;font-family:var(--mono);font-size:.72rem;color:var(--muted);cursor:pointer;user-select:none}
.av-toggle input{accent-color:var(--accent-2);width:15px;height:15px}
.av-toggles{display:flex;gap:14px;flex-wrap:wrap;justify-content:center;margin-top:10px}

/* ---------- interview accordion (reusable) ---------- */
.acc{border:1px solid var(--border);border-radius:13px;margin-bottom:10px;overflow:hidden;background:var(--panel);transition:border-color .2s}
.acc[open]{border-color:var(--border-2)}
.acc summary{list-style:none;cursor:pointer;padding:15px 18px;display:flex;align-items:center;gap:12px;font-weight:600;font-size:.96rem}
.acc summary::-webkit-details-marker{display:none}
.acc summary .q{font-family:var(--mono);color:var(--accent);font-size:.8rem;flex-shrink:0}
.acc summary .plus{margin-left:auto;color:var(--muted);transition:transform .25s;font-size:1.2rem;line-height:1;flex-shrink:0}
.acc[open] summary .plus{transform:rotate(45deg)}
.acc .ans{padding:0 18px 16px;color:var(--muted);font-size:.92rem;max-width:72ch}
.acc .ans code{font-family:var(--mono);font-size:.85em;background:var(--panel-2);padding:1px 5px;border-radius:5px;color:var(--accent)}

/* ---------- terminal output block (reusable) ---------- */
.term{background:#0a0f18;border:1px solid var(--border-2);border-radius:12px;overflow:hidden;font-family:var(--mono);margin-top:12px}
.term .tbar{display:flex;align-items:center;gap:7px;padding:8px 12px;background:rgba(255,255,255,.03);border-bottom:1px solid var(--border-2)}
.term .tbar i{width:11px;height:11px;border-radius:50%;display:inline-block}
.term .tbar .r{background:#ff5f57} .term .tbar .y{background:#febc2e} .term .tbar .gg{background:#28c840}
.term .tbar span{margin-left:6px;font-size:.68rem;color:var(--faint);letter-spacing:.04em}
.term pre{margin:0;padding:13px 15px;font-size:.8rem;line-height:1.6;overflow-x:auto;white-space:pre-wrap;word-break:break-word}
.term .cmd{color:var(--faint)} .term .cmd::before{content:"$ ";color:var(--accent)}
.term .out{color:#cbd5e1} .term .comm{color:#5b6b82;font-style:italic}
.term .hi{color:#7ee787} .term .em{color:var(--accent-2)}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .rv{opacity:1!important;transform:none!important;transition:none!important}
}