:root{
  --bg:#EEF1F4; --surface:#FFFFFF; --sunk:#E3E8ED; --ink:#18232E; --muted:#56636F; --line:#D0D8E0;
  --accent:#2446C6; --accent-ink:#FFFFFF; --keep:#1F7A4D; --drop:#B83A3A; --hl:#F2B632;
  --g1:#DCE6FF; --g2:#FCE7C0; --g3:#D4EEDF;
  --code-bg:#17212B; --code-ink:#DDE5EE; --kw:#8FB0FF; --fn:#F2C46B; --str:#8FD6A8; --num:#F29B8F; --cm:#7D8B99;
  --radius-s:6px; --radius-m:10px;
  color-scheme: light;
  box-sizing:border-box;
  padding-top:env(safe-area-inset-top,0px);
  padding-bottom:env(safe-area-inset-bottom,0px);
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --bg:#10161D; --surface:#18212B; --sunk:#0C1117; --ink:#E6ECF2; --muted:#95A3B1; --line:#2B3744;
    --accent:#7C9BFF; --accent-ink:#0C1117; --keep:#5BC38E; --drop:#F07A7A; --hl:#F2B632;
    --g1:#23325E; --g2:#4A3A17; --g3:#1C3F2D;
    --code-bg:#0B1016; color-scheme: dark;
  }
}
:root[data-theme="dark"]{
  --bg:#10161D; --surface:#18212B; --sunk:#0C1117; --ink:#E6ECF2; --muted:#95A3B1; --line:#2B3744;
  --accent:#7C9BFF; --accent-ink:#0C1117; --keep:#5BC38E; --drop:#F07A7A; --hl:#F2B632;
  --g1:#23325E; --g2:#4A3A17; --g3:#1C3F2D;
  --code-bg:#0B1016; color-scheme: dark;
}
html{scroll-padding-top:calc(env(safe-area-inset-top,0px) + 72px);scroll-behavior:smooth}
@media (prefers-reduced-motion: reduce){html{scroll-behavior:auto}*{transition:none!important;animation:none!important}}
*,*::before,*::after{box-sizing:inherit}
body{margin:0;background:var(--bg);color:var(--ink);font:400 17px/1.6 "Atkinson Hyperlegible",system-ui,-apple-system,"Segoe UI",sans-serif}
body::before{content:"";position:fixed;inset:0 0 auto;height:env(safe-area-inset-top,0px);z-index:10;background:var(--surface)}
h1,h2,h3{font-family:"Bricolage Grotesque","Atkinson Hyperlegible",system-ui,sans-serif;line-height:1.15;margin:0}
h2{font-size:clamp(1.6rem,3.2vw,2.1rem);font-weight:800;letter-spacing:-.01em}
h3{font-size:1.2rem;font-weight:700}
p{margin:.6em 0}
a{color:var(--accent)}
code,pre,.mono{font-family:"JetBrains Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,monospace}
:focus-visible{outline:3px solid var(--hl);outline-offset:2px;border-radius:4px}

/* top bar */
.top{position:sticky;top:env(safe-area-inset-top,0px);z-index:20;background:var(--surface);border-bottom:1px solid var(--line)}
.top-inner{display:flex;align-items:center;gap:16px;padding:12px 20px;max-width:1240px;margin:0 auto}
.brand{font-family:"Bricolage Grotesque",sans-serif;font-weight:800;font-size:1.25rem;text-decoration:none;color:var(--ink);white-space:nowrap}
.brand span{display:inline-block;background:var(--ink);color:var(--surface);padding:0 6px;border-radius:4px;margin-right:2px}
.progress-pill{margin-left:auto;display:flex;align-items:center;gap:10px;font-size:.9rem;color:var(--muted);white-space:nowrap}
.bar{width:120px;height:8px;background:var(--sunk);border-radius:99px;overflow:hidden}
.bar i{display:block;height:100%;background:var(--keep);width:0;transition:width .4s}
.mobile-nav{display:none;overflow-x:auto;gap:6px;padding:0 16px 10px;scrollbar-width:none}
.mobile-nav::-webkit-scrollbar{display:none}
.mobile-nav a{flex:none;font-size:.88rem;padding:5px 12px;border-radius:99px;background:var(--sunk);color:var(--ink);text-decoration:none}

/* layout */
.layout{display:grid;grid-template-columns:210px minmax(0,1fr);gap:40px;max-width:1240px;margin:0 auto;padding:28px 20px 80px}
.side{position:sticky;top:calc(env(safe-area-inset-top,0px) + 80px);align-self:start}
.side ol{list-style:none;margin:0;padding:0;counter-reset:s}
.side li{counter-increment:s}
.side a{display:flex;gap:10px;padding:7px 10px;border-radius:var(--radius-s);color:var(--muted);text-decoration:none;font-size:.95rem}
.side a::before{content:counter(s);font-family:"JetBrains Mono",monospace;font-size:.8rem;width:1.2em;padding-top:2px;color:var(--muted)}
.side a:hover{background:var(--sunk);color:var(--ink)}
.side a.active{background:var(--ink);color:var(--surface)}
.side a.active::before{color:var(--hl)}
main{min-width:0}
section{padding:8px 0 56px;border-bottom:1px solid var(--line);margin-bottom:48px}
section:last-of-type{border-bottom:0}
.lead{font-size:1.1rem;color:var(--muted);max-width:68ch}
.prose{max-width:70ch}
@media (max-width:900px){
  html{scroll-padding-top:calc(env(safe-area-inset-top,0px) + 116px)}
  .layout{grid-template-columns:1fr;padding-top:18px}
  .side{display:none}
  .mobile-nav{display:flex}
  .bar{width:70px}
}

/* hero */
.hero h1{font-size:clamp(2.2rem,5.4vw,3.6rem);font-weight:800;letter-spacing:-.025em;max-width:16ch}
.hero .lead{margin-top:12px}
.stepper{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.1fr);gap:20px;margin-top:28px}
@media (max-width:760px){.stepper{grid-template-columns:minmax(0,1fr)}}
.query{background:var(--code-bg);color:var(--code-ink);border-radius:var(--radius-m);padding:16px 0;font-size:.92rem;align-self:start}
.qline{display:grid;grid-template-columns:44px 1fr;align-items:center;padding:4px 14px 4px 0;cursor:pointer;border-left:4px solid transparent;transition:background .2s}
.qline:hover{background:rgba(255,255,255,.04)}
.qline .ord{justify-self:center;font-size:.75rem;width:22px;height:22px;display:grid;place-items:center;border-radius:50%;border:1px solid var(--cm);color:var(--cm)}
.qline.done .ord{border-color:var(--str);color:var(--str)}
.qline.on{background:rgba(242,182,50,.13);border-left-color:var(--hl)}
.qline.on .ord{background:var(--hl);border-color:var(--hl);color:#17212B;font-weight:600}
.qline code{white-space:pre}
.stage{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius-m);padding:18px;min-height:360px;display:flex;flex-direction:column}
.stage h3{margin-bottom:4px}
.stage .note{color:var(--muted);font-size:.97rem;margin:0 0 12px}
.why{margin-top:auto;padding:10px 12px;background:var(--sunk);border-radius:var(--radius-s);font-size:.93rem}
.why b{color:var(--ink)}
.controls{display:flex;gap:8px;margin-top:14px;align-items:center}
.btn{font:inherit;font-size:.95rem;border:1px solid var(--line);background:var(--surface);color:var(--ink);padding:7px 14px;border-radius:var(--radius-s);cursor:pointer}
.btn:hover{border-color:var(--ink)}
.btn.primary{background:var(--accent);border-color:var(--accent);color:var(--accent-ink)}
.btn[disabled]{opacity:.4;cursor:default}
.controls .count{margin-left:auto;color:var(--muted);font-size:.88rem}

/* data tables */
.tw{overflow-x:auto;max-width:100%}
table.data{border-collapse:collapse;font-size:.9rem;font-family:"JetBrains Mono",monospace;min-width:100%}
table.data th{text-align:left;font-weight:600;color:var(--muted);border-bottom:2px solid var(--line);padding:5px 10px;white-space:nowrap}
table.data td{padding:5px 10px;border-bottom:1px solid var(--line);white-space:nowrap;transition:opacity .3s,background .3s}
table.data tr.drop td{opacity:.35;text-decoration:line-through;text-decoration-color:var(--drop)}
table.data tr.drop td:last-child{text-decoration:none;opacity:1;color:var(--drop);font-family:"Atkinson Hyperlegible",sans-serif;font-size:.82rem}
table.data tr.gA td{background:var(--g1)} table.data tr.gB td{background:var(--g2)} table.data tr.gC td{background:var(--g3)}
table.data tr.ghead td{font-family:"Atkinson Hyperlegible",sans-serif;font-weight:700;font-size:.85rem;border-bottom:0;padding-top:10px}
table.data td.null{color:var(--muted);font-style:italic}
table.data td.new{color:var(--accent);font-weight:600}

/* generic blocks */
.cols{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:18px;margin-top:20px}
.panel{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius-m);padding:18px}
.panel h3{margin-bottom:6px}
pre.code{background:var(--code-bg);color:var(--code-ink);border-radius:var(--radius-s);padding:12px 14px;font-size:.85rem;line-height:1.55;overflow-x:auto;margin:10px 0 0;position:relative}
.kw{color:var(--kw);font-weight:600}.fn{color:var(--fn)}.str{color:var(--str)}.num{color:var(--num)}.cm{color:var(--cm);font-style:italic}
.copy{position:absolute;top:6px;right:6px;font:600 .72rem "Atkinson Hyperlegible",sans-serif;background:rgba(255,255,255,.1);color:var(--code-ink);border:0;border-radius:4px;padding:3px 8px;cursor:pointer}
.copy:hover{background:rgba(255,255,255,.2)}

/* decode */
.five{counter-reset:q;list-style:none;padding:0;margin:20px 0 0;display:grid;gap:10px;max-width:72ch}
.five li{counter-increment:q;display:grid;grid-template-columns:40px 1fr;gap:12px;align-items:start;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius-m);padding:14px 16px}
.five li::before{content:counter(q);font:800 1.5rem/1 "Bricolage Grotesque",sans-serif;color:var(--accent)}
.five b{display:block}
.five span{color:var(--muted);font-size:.96rem}
.practice{margin-top:28px}
.seg{display:inline-flex;flex-wrap:wrap;gap:4px;background:var(--sunk);padding:4px;border-radius:var(--radius-m)}
.seg button{font:inherit;font-size:.9rem;border:0;background:transparent;color:var(--ink);padding:6px 12px;border-radius:var(--radius-s);cursor:pointer}
.seg button[aria-pressed="true"]{background:var(--surface);box-shadow:0 0 0 1px var(--line);font-weight:700}
.reveal-list{list-style:none;padding:0;margin:14px 0 0;display:grid;gap:8px}
.reveal-list li{border:1px solid var(--line);border-radius:var(--radius-s);background:var(--surface)}
.reveal-list button{all:unset;box-sizing:border-box;display:flex;gap:10px;width:100%;padding:10px 14px;cursor:pointer;font-weight:700}
.reveal-list button:focus-visible{outline:3px solid var(--hl)}
.reveal-list button::after{content:"Reveal";margin-left:auto;font-weight:400;font-size:.85rem;color:var(--accent)}
.reveal-list li.open button::after{content:""}
.reveal-list .ans{display:none;padding:0 14px 12px 14px;color:var(--ink)}
.reveal-list li.open .ans{display:block}

/* joins */
.joinwrap{display:grid;grid-template-columns:auto auto 1fr;gap:18px;margin-top:16px;align-items:start}
@media (max-width:760px){.joinwrap{grid-template-columns:1fr 1fr}.joinwrap .result{grid-column:1/-1}}
.tlabel{font-weight:700;font-size:.9rem;margin-bottom:4px}
table.data tr.hit td{background:var(--g3)}
table.data tr.miss td{opacity:.5}
.ctrl-row{display:flex;flex-wrap:wrap;gap:14px;align-items:center;margin-top:14px}
.ctrl-row label{font-size:.9rem;color:var(--muted)}
select{font:inherit;font-size:.92rem;padding:6px 10px;border-radius:var(--radius-s);border:1px solid var(--line);background:var(--surface);color:var(--ink)}
.explain{margin-top:14px;padding:12px 14px;border-left:4px solid var(--accent);background:var(--surface);border-radius:0 var(--radius-s) var(--radius-s) 0;max-width:72ch}
.explain.warn{border-left-color:var(--drop)}

/* compare table */
table.cmp{border-collapse:collapse;width:100%;font-size:.95rem}
table.cmp th,table.cmp td{text-align:left;padding:10px 12px;border-bottom:1px solid var(--line);vertical-align:top}
table.cmp th{font-family:"Bricolage Grotesque",sans-serif;font-size:1rem}
table.cmp td:first-child{font-weight:700;white-space:nowrap}

/* phrases */
.chips{display:flex;flex-wrap:wrap;gap:8px;margin-top:18px}
.chip{font:inherit;font-size:.95rem;border:1px solid var(--line);background:var(--surface);color:var(--ink);padding:7px 14px;border-radius:99px;cursor:pointer}
.chip:hover{border-color:var(--ink)}
.chip[aria-pressed="true"]{background:var(--ink);color:var(--surface);border-color:var(--ink)}
.phrase-out{margin-top:16px;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius-m);padding:18px;max-width:80ch}
.phrase-out .tool{font:800 1.35rem/1.2 "Bricolage Grotesque",sans-serif}
.phrase-out .seen{font-size:.9rem;color:var(--muted);margin-top:10px}

/* quiz */
.quiz{max-width:72ch;margin-top:18px}
.qcard{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius-m);padding:20px}
.qcard .qn{font-size:.85rem;color:var(--muted)}
.qcard .qt{font-weight:700;font-size:1.08rem;margin:4px 0 14px}
.opts{display:grid;gap:8px}
.opt{font:inherit;text-align:left;border:1px solid var(--line);background:var(--bg);color:var(--ink);padding:10px 14px;border-radius:var(--radius-s);cursor:pointer;font-family:"JetBrains Mono",monospace;font-size:.86rem}
.opt:hover:not([disabled]){border-color:var(--ink)}
.opt.right{border-color:var(--keep);background:color-mix(in srgb,var(--keep) 14%,var(--surface))}
.opt.wrong{border-color:var(--drop);background:color-mix(in srgb,var(--drop) 12%,var(--surface))}
.opt[disabled]{cursor:default}
.qexp{margin-top:12px;font-size:.96rem;display:none}
.qexp.show{display:block}

/* dialect: everything that differs is rendered twice; hide the inactive one */
html[data-db="pg"] [data-db="my"], html[data-db="my"] [data-db="pg"]{display:none!important}
.dbtoggle{margin-left:auto;padding:3px}
.dbtoggle button{padding:4px 10px;font-size:.85rem}
.top .progress-pill{margin-left:12px}
.brand i{font-style:normal}
.short{display:none}
.query{overflow-x:auto}
@media (max-width:560px){.progress-pill .bar,.long{display:none}.short{display:inline}.brand{font-size:1.05rem}.top-inner{gap:10px;padding:10px 16px}.top .progress-pill{margin-left:0}}

/* tracker */
.pfilter{display:flex;flex-wrap:wrap;gap:12px;align-items:center;margin-top:16px}
.ptools{display:flex;flex-wrap:wrap;gap:8px;margin-top:12px}
.ptools .btn{font-size:.85rem;padding:5px 12px}
.psec{margin-top:26px}
.psec h3{display:flex;align-items:baseline;gap:10px;flex-wrap:wrap}
.psec h3 small{font:400 .85rem "Atkinson Hyperlegible",sans-serif;color:var(--muted)}
.plist{list-style:none;padding:0;margin:10px 0 0;border:1px solid var(--line);border-radius:var(--radius-m);background:var(--surface);overflow:hidden}
.prow{display:flex;align-items:center;gap:12px;padding:9px 14px;border-bottom:1px solid var(--line);border-left:4px solid transparent}
.prow:last-child{border-bottom:0}
.prow .pn{font-family:"JetBrains Mono",monospace;font-size:.82rem;color:var(--muted);width:3.4em;flex:none}
.prow .pt{flex:1;min-width:0}
.prow .pt a{color:var(--ink);text-decoration:none}
.prow .pt a:hover{text-decoration:underline}
.prow.st-solved .pt a{color:var(--muted)}
.prow.st-solved{border-left-color:var(--keep)}
.prow.st-attempted{border-left-color:var(--hl)}
.prow.st-revisit{border-left-color:var(--accent)}
.prow .lc{font-size:.82rem;white-space:nowrap}
.dots{font-size:.75rem;color:var(--muted);white-space:nowrap}
.tag{font-size:.75rem;padding:1px 8px;border-radius:99px;white-space:nowrap;background:var(--sunk);color:var(--muted)}
.tag.Easy{color:var(--keep)} .tag.Medium{color:#B07A00} .tag.Hard{color:var(--drop)}
:root[data-theme="dark"] .tag.Medium{color:var(--hl)}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]) .tag.Medium{color:var(--hl)}}
select.pstat{font-size:.82rem;padding:3px 6px;flex:none}
.empty{color:var(--muted)}
@media (max-width:560px){.prow{flex-wrap:wrap;gap:6px 10px}.prow .pt{flex-basis:calc(100% - 4.5em)}.prow .lc{display:none}}

/* study plan */
.plan{list-style:none;padding:0;margin:18px 0 0;max-width:76ch;display:grid;gap:0}
.plan li{display:grid;grid-template-columns:64px 1fr;gap:14px;padding:14px 0;border-bottom:1px solid var(--line)}
.plan li:last-child{border-bottom:0}
.plan .t{font-family:"JetBrains Mono",monospace;font-size:.85rem;color:var(--muted);padding-top:3px}
.plan b a{font-weight:700}
.plan .pc{font-size:.88rem;color:var(--muted);margin-left:6px}
.plan p{margin:.3em 0 0;color:var(--muted);font-size:.95rem}

/* problem page */
.crumbs{font-size:.9rem;color:var(--muted);margin-bottom:10px}
.crumbs a{color:var(--muted)}
.pmeta{display:flex;flex-wrap:wrap;gap:10px;align-items:center;margin-top:12px}
.single{max-width:860px;margin:0 auto;padding:28px 20px 80px}
.single section{padding-bottom:32px;margin-bottom:32px}
.single h1{font-size:clamp(1.7rem,4vw,2.5rem);font-weight:800;letter-spacing:-.02em}
.single h2{font-size:1.4rem;margin-bottom:10px}
details.hint{border:1px solid var(--line);border-radius:var(--radius-s);background:var(--surface);margin-top:8px}
details.hint summary{cursor:pointer;padding:10px 14px;font-weight:700}
details.hint[open] summary{border-bottom:1px solid var(--line)}
details.hint > div{padding:10px 14px}
details.hint pre.code{margin:0}
label.fld{display:block;font-weight:700;margin:14px 0 6px}
textarea{width:100%;font:.9rem/1.5 "JetBrains Mono",monospace;padding:10px 12px;border:1px solid var(--line);border-radius:var(--radius-s);background:var(--surface);color:var(--ink);resize:vertical}
textarea.notes{font-family:"Atkinson Hyperlegible",sans-serif;font-size:.95rem}
.saved{font-size:.8rem;color:var(--muted);margin-left:8px;font-weight:400}
.pager{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap}
footer{color:var(--muted);font-size:.9rem;max-width:70ch}