/* Gridline — clean white/grey ground, test-app blue accent, highlighter yellow marks "you are here". */
:root{
  --paper:#F6F7F9; --surface:#FFFFFF; --ink:#1B1C1E; --ink-2:#5B5F66; --line:#D7DAE0;
  --grid:rgba(50,77,199,.035); --accent:#324DC7; --accent-ink:#FFFFFF; --hi:#FFE066; --hi-ink:#1B1C1E;
  --good:#1D7A4C; --good-bg:#E3F3E9; --bad:#B3342B; --bad-bg:#FBE8E5; --warn:#8F5E00; --warn-bg:#FFF3D6;
  --f-display:"Bricolage Grotesque","Segoe UI",system-ui,sans-serif;
  --f-ui:"IBM Plex Sans","Segoe UI",system-ui,sans-serif;
  --f-read:"Source Serif 4",Georgia,"Times New Roman",serif;
  --f-mono:"IBM Plex Mono",ui-monospace,Menlo,Consolas,monospace;
  color-scheme:light;
}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){
  --paper:#0E1422; --surface:#161E30; --ink:#E6EBF5; --ink-2:#9AA5BC; --line:#2A3551;
  --grid:rgba(140,170,255,.05); --accent:#91B1FF; --accent-ink:#0E1422; --hi:#F2CB45; --hi-ink:#16213A;
  --good:#63CF93; --good-bg:#14301F; --bad:#FF8C80; --bad-bg:#3B1B18; --warn:#E8B955; --warn-bg:#35290F; color-scheme:dark}}
:root[data-theme="dark"]{
  --paper:#0E1422; --surface:#161E30; --ink:#E6EBF5; --ink-2:#9AA5BC; --line:#2A3551;
  --grid:rgba(140,170,255,.05); --accent:#91B1FF; --accent-ink:#0E1422; --hi:#F2CB45; --hi-ink:#16213A;
  --good:#63CF93; --good-bg:#14301F; --bad:#FF8C80; --bad-bg:#3B1B18; --warn:#E8B955; --warn-bg:#35290F; color-scheme:dark}

*{box-sizing:border-box}
html,body{margin:0}
body{background-color:var(--paper);color:var(--ink);font-family:var(--f-ui);font-size:15px;line-height:1.5;
  background-image:linear-gradient(var(--grid) 1px,transparent 1px),linear-gradient(90deg,var(--grid) 1px,transparent 1px);background-size:24px 24px;min-height:100vh}
h1,h2,h3,h4{font-family:var(--f-display);text-wrap:balance;margin:0;line-height:1.15}
p{margin:0}
button,input,select,textarea{font:inherit;color:inherit}
[hidden]{display:none!important}
:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
a{color:var(--accent)}
.mono{font-family:var(--f-mono);font-variant-numeric:tabular-nums}
.muted{color:var(--ink-2)}
.small{font-size:.85rem}
mark{background:linear-gradient(transparent 55%,var(--hi) 55%,var(--hi) 94%,transparent 94%);color:inherit;padding:0 .08em}

.top{position:sticky;top:env(safe-area-inset-top,0px);z-index:20;background:var(--paper);border-bottom:1px solid var(--line)}
.top-in{max-width:1080px;margin:0 auto;padding:10px 16px;display:flex;flex-wrap:wrap;gap:8px 18px;align-items:center;justify-content:space-between}
.brand{display:flex;align-items:center;gap:10px;font-family:var(--f-display);font-weight:800;font-size:1.2rem;background:none;border:0;cursor:pointer;padding:0;text-decoration:none;color:var(--ink)}
.brand small{font-family:var(--f-ui);font-weight:500;font-size:.78rem;color:var(--ink-2);letter-spacing:.04em;text-transform:uppercase}
.logo{width:28px;height:28px;display:grid;grid-template-columns:1fr 1fr;gap:3px}
.logo i{border:1.5px solid var(--ink);border-radius:50%}
.logo i:nth-child(2){background:var(--ink)}
.nav{display:flex;flex-wrap:wrap;gap:2px;align-items:center}
.nav button{background:none;border:0;padding:8px 10px;border-radius:8px;cursor:pointer;color:var(--ink-2);font-weight:500}
.nav button:hover{color:var(--ink)}
.nav button[aria-current="page"]{color:var(--ink);font-weight:600}
.nav button[aria-current="page"] span{background:linear-gradient(transparent 58%,var(--hi) 58%,var(--hi) 92%,transparent 92%)}
.nav .live{display:inline-block;width:7px;height:7px;border-radius:50%;background:var(--bad);margin-left:6px;vertical-align:middle}
.me{display:flex;align-items:center;gap:8px;margin-left:6px}
.me img{width:30px;height:30px;border-radius:50%;border:1px solid var(--line)}

.wrap{max-width:1080px;margin:0 auto;padding-inline:16px;padding-block:28px 56px}
.panel{background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:20px;min-width:0}
.eyebrow{font-size:.74rem;letter-spacing:.09em;text-transform:uppercase;color:var(--ink-2);font-weight:600}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;font-weight:600;padding:10px 18px;border-radius:10px;border:1px solid var(--line);background:var(--surface);color:var(--ink);cursor:pointer;text-decoration:none}
.btn:hover{border-color:var(--ink-2)}
.btn.primary{background:var(--accent);color:var(--accent-ink);border-color:transparent;border-radius:999px}
.btn.primary:hover{filter:brightness(1.08)}
.btn.ghost{background:transparent}
.btn.danger{background:var(--bad);color:var(--surface);border-color:transparent}
.btn:disabled{opacity:.45;cursor:not-allowed}
.btn.sm{padding:6px 12px;font-size:.88rem}
.row{display:flex;flex-wrap:wrap;gap:10px;align-items:center}
.gsi{background:var(--surface);color:var(--ink);border:1px solid var(--line);padding:11px 18px;border-radius:999px}
.gsi svg{width:18px;height:18px}
/* Google sign-in: always visible in the header + a clear box at the top of the landing page */
.nav button.gsi-top{background:#fff;color:#1f1f1f;border:1px solid #747775;border-radius:999px;padding:8px 16px;font-weight:600;display:inline-flex;gap:10px;align-items:center;box-shadow:0 1px 2px rgba(0,0,0,.12)}
.nav button.gsi-top:hover{background:#f2f5fb}
.signin-box{display:flex;flex-wrap:wrap;gap:14px 22px;align-items:center;justify-content:space-between;padding:18px 20px;border:2px solid var(--ink);border-radius:14px;background:var(--surface);max-width:760px}
.signin-box>div{display:grid;gap:4px}
.signin-box b{font-size:1.1rem}
.gsi.gsi-lg{background:#fff;color:#1f1f1f;border:1px solid #747775;padding:14px 26px;font-size:1.05rem;font-weight:600;box-shadow:0 1px 3px rgba(0,0,0,.18)}
.gsi.gsi-lg:hover{background:#f2f5fb}
.gsi.gsi-lg svg{width:22px;height:22px}
@media (max-width:560px){.signin-box .gsi-lg{width:100%;justify-content:center}}

.hero{display:grid;gap:14px;margin-bottom:26px}
.hero h1{font-size:clamp(2rem,5.2vw,3.3rem);font-weight:800;letter-spacing:-.025em;max-width:18ch}
.hero p{font-family:var(--f-read);font-size:1.12rem;color:var(--ink-2);max-width:58ch}
.stats{display:flex;flex-wrap:wrap;gap:10px 28px;padding:14px 0;border-block:1px solid var(--line);margin-bottom:26px}
.stat b{display:block;font-family:var(--f-mono);font-size:1.5rem;font-weight:600;font-variant-numeric:tabular-nums}
.stat span{font-size:.82rem;color:var(--ink-2)}
.home-grid{display:grid;grid-template-columns:minmax(0,1.65fr) minmax(0,1fr);gap:20px;align-items:start}
.side{display:grid;gap:20px}
@media (max-width:860px){.home-grid{grid-template-columns:minmax(0,1fr)}}
.sec-h{display:flex;justify-content:space-between;align-items:baseline;gap:10px;margin-bottom:12px;flex-wrap:wrap}
.sec-h h2{font-size:1.2rem}
.dom-list{display:grid;gap:14px}
.dom-row{display:grid;gap:6px}
.dom-row .top-l{display:flex;justify-content:space-between;gap:10px;font-size:.92rem}
.dom-row .top-l span:last-child{font-family:var(--f-mono);color:var(--ink-2);font-size:.85rem;white-space:nowrap}
.track{height:8px;background:var(--paper);border:1px solid var(--line);border-radius:99px;overflow:hidden}
.track i{display:block;height:100%;background:var(--accent);border-radius:99px;transition:width .4s}
.weight{font-size:.78rem;color:var(--ink-2)}
.hist{list-style:none;margin:0;padding:0;display:grid;gap:8px}
.hist li{display:flex;justify-content:space-between;gap:10px;font-size:.9rem;padding-bottom:8px;border-bottom:1px dashed var(--line)}
.hist li:last-child{border-bottom:0;padding-bottom:0}
.features{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:12px;margin:8px 0 26px}
.features div{border-left:3px solid var(--hi);padding:4px 12px}
.features b{display:block;font-family:var(--f-display);font-size:1.05rem;margin-bottom:2px}
.features span{font-size:.88rem;color:var(--ink-2)}

.q{background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:22px;min-width:0}
.q-meta{display:flex;flex-wrap:wrap;gap:8px 10px;align-items:center;margin-bottom:16px;font-size:.84rem}
.dom{font-weight:600}
.skill{color:var(--ink-2)}
.lvl{font-size:.7rem;text-transform:uppercase;letter-spacing:.07em;font-weight:600;padding:2px 8px;border-radius:99px;border:1px solid currentColor}
.lvl-1{color:var(--good)} .lvl-2{color:var(--warn)} .lvl-3{color:var(--bad)}
.ctr{font-family:var(--f-mono);color:var(--ink-2)}
.flag{margin-left:auto;background:none;border:1px solid var(--line);border-radius:8px;padding:4px 10px;cursor:pointer;font-size:.82rem;color:var(--ink-2)}
.flag[aria-pressed="true"]{background:var(--hi);color:var(--hi-ink);border-color:var(--hi);font-weight:600}
.q-stem{font-family:var(--f-read);font-size:1.14rem;line-height:1.65;max-width:65ch;margin-bottom:18px;white-space:pre-line;overflow-x:auto}
.choices{list-style:none;margin:0;padding:0;display:grid;gap:10px}
.choices li{display:flex;gap:8px;min-width:0}
.ch{flex:1;min-width:0;display:flex;gap:14px;align-items:center;text-align:left;padding:11px 14px;border:1.5px solid var(--line);border-radius:12px;background:var(--surface);cursor:pointer;font-family:var(--f-read);font-size:1.06rem}
.ch:hover:not(:disabled){border-color:var(--ink-2)}
.ch:disabled{cursor:default}
.ch .ct{min-width:0;overflow-x:auto}
.bub{flex:none;width:30px;height:30px;border-radius:50%;border:1.5px solid var(--ink-2);display:grid;place-items:center;font-family:var(--f-ui);font-weight:600;font-size:.84rem}
.ch.sel{border-color:var(--accent);box-shadow:0 0 0 1px var(--accent)}
.ch.sel .bub{background:var(--accent);color:var(--accent-ink);border-color:var(--accent)}
.ch.struck .ct,.ch.struck .bub{opacity:.4}
.ch.struck .ct{text-decoration:line-through}
.ch.right{border-color:var(--good);background:var(--good-bg);box-shadow:none}
.ch.right .bub{background:var(--good);border-color:var(--good);color:var(--surface)}
.ch.wrong{border-color:var(--bad);background:var(--bad-bg);box-shadow:none}
.ch.wrong .bub{background:var(--bad);border-color:var(--bad);color:var(--surface)}
.strike{flex:none;width:42px;border:1px solid var(--line);border-radius:10px;background:transparent;color:var(--ink-2);cursor:pointer;text-decoration:line-through;font-weight:600;font-size:.85rem}
.strike[aria-pressed="true"]{background:var(--ink);color:var(--paper);border-color:var(--ink)}
.strike:disabled{opacity:.35;cursor:default}
.spr{display:grid;gap:6px;max-width:420px}
.spr label{font-weight:600;font-size:.9rem}
.spr-in{font-family:var(--f-mono);font-size:1.35rem;padding:10px 14px;width:min(100%,220px);border:1.5px solid var(--line);border-radius:10px;background:var(--surface);color:var(--ink)}
.spr-in:focus{border-color:var(--accent);outline:none;box-shadow:0 0 0 1px var(--accent)}
.spr-in.ok{border-color:var(--good);background:var(--good-bg)}
.spr-in.no{border-color:var(--bad);background:var(--bad-bg)}
.hint{font-size:.82rem;color:var(--ink-2)}
.fb{margin-top:18px;padding:12px 14px;border-radius:10px;font-weight:500}
.fb.good{background:var(--good-bg);color:var(--good)}
.fb.bad{background:var(--bad-bg);color:var(--bad)}
.expl{margin-top:12px;padding:14px 16px;border-left:3px solid var(--hi);background:var(--paper);border-radius:0 10px 10px 0}
.expl h4{font-size:.8rem;text-transform:uppercase;letter-spacing:.08em;font-family:var(--f-ui);color:var(--ink-2);margin-bottom:6px}
.expl div{font-family:var(--f-read);font-size:1.02rem;line-height:1.6;overflow-x:auto;white-space:pre-line}
.q-actions{margin-top:18px;display:flex;flex-wrap:wrap;gap:10px}

.page-h{display:grid;gap:6px;margin-bottom:18px}
.page-h h1{font-size:clamp(1.7rem,4vw,2.3rem);font-weight:800;letter-spacing:-.02em}
.page-h p{color:var(--ink-2);max-width:62ch}
.filters{display:grid;gap:10px;margin-bottom:16px}
.fgroup{display:flex;flex-wrap:wrap;gap:6px;align-items:center}
.fgroup > span{font-size:.78rem;text-transform:uppercase;letter-spacing:.07em;color:var(--ink-2);font-weight:600;min-width:84px}
.chip{border:1px solid var(--line);background:var(--surface);border-radius:99px;padding:5px 12px;cursor:pointer;font-size:.88rem}
.chip[aria-pressed="true"]{background:var(--ink);color:var(--paper);border-color:var(--ink)}
.pbar{display:flex;flex-wrap:wrap;gap:10px;justify-content:space-between;align-items:center;margin-bottom:12px}
.pinfo{font-family:var(--f-mono);font-size:.88rem;color:var(--ink-2)}
.banner{display:flex;flex-wrap:wrap;gap:10px;align-items:center;justify-content:space-between;background:var(--warn-bg);color:var(--warn);border-radius:10px;padding:10px 14px;margin-bottom:14px;font-weight:500}
.empty{text-align:center;padding:40px 20px}
.empty h3{margin-bottom:6px}
.toast{position:fixed;left:50%;transform:translateX(-50%);bottom:calc(16px + env(safe-area-inset-bottom,0px));background:var(--ink);color:var(--paper);padding:10px 16px;border-radius:10px;z-index:50;max-width:calc(100% - 32px);font-size:.9rem}

.tbar{display:flex;flex-wrap:wrap;gap:10px 16px;align-items:center;justify-content:space-between;margin-bottom:14px;padding:12px 16px}
.timer{font-family:var(--f-mono);font-size:1.5rem;font-weight:600;font-variant-numeric:tabular-nums}
.timer.low{color:var(--bad)}
.tnav{display:grid;grid-template-columns:repeat(auto-fill,minmax(44px,1fr));gap:6px;margin-bottom:14px}
.cell{position:relative;height:44px;border:1.5px dashed var(--ink-2);border-radius:8px;background:var(--surface);cursor:pointer;font-family:var(--f-mono);font-weight:600}
.cell.ans{border-style:solid;background:var(--accent);color:var(--accent-ink);border-color:var(--accent)}
.cell.cur{outline:3px solid var(--hi);outline-offset:1px}
.cell.flg::after{content:"";position:absolute;top:-1px;right:-1px;border-style:solid;border-width:0 12px 12px 0;border-color:transparent var(--bad) transparent transparent;border-top-right-radius:6px}
.legend{display:flex;flex-wrap:wrap;gap:14px;font-size:.82rem;color:var(--ink-2);margin-bottom:10px}
.legend i{display:inline-block;width:12px;height:12px;border-radius:3px;margin-right:6px;vertical-align:-1px;border:1.5px dashed var(--ink-2)}
.legend i.a{background:var(--accent);border:0}
.legend i.f{background:var(--bad);border:0}
.tfoot{display:flex;justify-content:space-between;gap:10px;margin-top:14px;flex-wrap:wrap}
.intro{display:grid;grid-template-columns:minmax(0,1.3fr) minmax(0,1fr);gap:20px;align-items:start}
@media (max-width:820px){.intro{grid-template-columns:minmax(0,1fr)}}
.facts{list-style:none;margin:14px 0 20px;padding:0;display:grid;gap:10px}
.facts li{display:flex;gap:12px;align-items:baseline}
.facts b{font-family:var(--f-mono);min-width:64px}
.score{display:flex;flex-wrap:wrap;gap:16px 36px;align-items:flex-end;margin-bottom:6px}
.score .big{font-family:var(--f-mono);font-size:clamp(2.4rem,8vw,3.6rem);font-weight:600;line-height:1;font-variant-numeric:tabular-nums}
.score .big small{font-size:.35em;color:var(--ink-2);font-weight:500}
.res-grid{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:20px;margin-top:20px}
@media (max-width:760px){.res-grid{grid-template-columns:minmax(0,1fr)}}
.rlist{list-style:none;margin:0;padding:0;display:grid;gap:8px}
.rlist details{border:1px solid var(--line);border-radius:10px;background:var(--surface)}
.rlist summary{display:flex;gap:10px;align-items:center;padding:10px 12px;cursor:pointer;flex-wrap:wrap}
.rlist summary .n{font-family:var(--f-mono);font-weight:600;width:28px}
.rlist .body{padding:0 14px 14px}
.rlist .body .q-stem{font-size:1.02rem;margin-bottom:8px}
.pill{font-size:.74rem;font-weight:600;padding:2px 8px;border-radius:99px}
.pill.ok{background:var(--good-bg);color:var(--good)}
.pill.no{background:var(--bad-bg);color:var(--bad)}
.pill.skip{background:var(--paper);color:var(--ink-2);border:1px solid var(--line)}

.rv-grid{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:20px}
@media (max-width:820px){.rv-grid{grid-template-columns:minmax(0,1fr)}}
.ilist{list-style:none;margin:0;padding:0;display:grid;gap:10px;max-height:560px;overflow:auto}
.ilist li{border-top:1px solid var(--line);padding-top:10px;display:grid;gap:4px}
.ilist li:first-child{border-top:0;padding-top:0}
.ilist .st{font-family:var(--f-read);font-size:.98rem;overflow-x:auto;white-space:pre-line}
.confirm{margin-top:12px;padding:12px 14px;border:1px solid var(--bad);border-radius:10px;display:grid;gap:10px}
.fgrid{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:12px}
.fcard{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:14px 16px;display:grid;gap:6px;min-width:0}
.fcard h3{font-size:.95rem;font-family:var(--f-ui);font-weight:600}
.fcard .fx{font-size:1.1rem;overflow-x:auto}
.fcard p{font-size:.84rem;color:var(--ink-2)}
.h2s{font-size:1.25rem;margin:30px 0 12px}
.fmt{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:12px}
.fmt div{border-left:3px solid var(--hi);padding:4px 12px}
.fmt b{display:block;font-family:var(--f-mono);font-size:1.4rem}
.fmt span{font-size:.84rem;color:var(--ink-2)}
.center{min-height:60vh;display:grid;place-items:center;text-align:center}
footer{max-width:1080px;margin:0 auto;padding:18px 16px 36px;font-size:.78rem;color:var(--ink-2);border-top:1px solid var(--line)}
mjx-container{max-width:100%}

/* Admin */
.kpis{display:grid;grid-template-columns:repeat(auto-fit,minmax(170px,1fr));gap:12px;margin-bottom:20px}
.kpi{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:14px 16px;min-width:0}
.kpi b{display:block;font-family:var(--f-mono);font-size:1.6rem;font-weight:600;font-variant-numeric:tabular-nums}
.kpi span{font-size:.82rem;color:var(--ink-2)}
.goal{display:grid;gap:8px;margin-bottom:20px}
.goal .track{height:12px}
.goal .track i{background:var(--hi)}
.charts{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:20px;margin-bottom:20px}
@media (max-width:860px){.charts{grid-template-columns:minmax(0,1fr)}}
.chart{position:relative}
.chart svg{display:block;width:100%;height:auto;overflow:visible}
.chart .tip{position:absolute;pointer-events:none;background:var(--ink);color:var(--paper);font-size:.8rem;padding:6px 8px;border-radius:6px;white-space:nowrap;transform:translate(-50%,-110%)}
.tablewrap{overflow-x:auto;border:1px solid var(--line);border-radius:12px;background:var(--surface)}
table{border-collapse:collapse;width:100%;font-size:.88rem}
th,td{padding:9px 12px;text-align:left;border-bottom:1px solid var(--line);white-space:nowrap}
th{font-weight:600;font-size:.78rem;text-transform:uppercase;letter-spacing:.05em;color:var(--ink-2);cursor:pointer;user-select:none;background:var(--surface);position:sticky;top:0}
td.num,th.num{text-align:right;font-family:var(--f-mono);font-variant-numeric:tabular-nums}
tr:last-child td{border-bottom:0}
.form{display:grid;gap:12px}
.form label{display:grid;gap:4px;font-weight:600;font-size:.88rem}
.form input,.form select,.form textarea{padding:9px 12px;border:1px solid var(--line);border-radius:8px;background:var(--surface);font-weight:400;min-width:0;width:100%}
.form textarea{font-family:var(--f-mono);font-size:.88rem;min-height:84px;resize:vertical}
.form .two{display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:12px}
.errs{color:var(--bad);font-size:.88rem;display:grid;gap:4px}
.okmsg{color:var(--good);font-weight:600}
.admin-grid{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:20px;align-items:start}
@media (max-width:900px){.admin-grid{grid-template-columns:minmax(0,1fr)}}
code{font-family:var(--f-mono);font-size:.88em;background:var(--paper);padding:1px 5px;border-radius:4px}
pre{font-family:var(--f-mono);font-size:.8rem;background:var(--paper);padding:12px;border-radius:8px;overflow-x:auto}
@media (prefers-reduced-motion:reduce){*{transition:none!important}}
/* MathJax: no stray scrollbars next to equations */
.q-stem,.ch .ct,.expl div,.fcard .fx,.ilist .st,.rlist .body .q-stem{overflow:visible!important}
mjx-container[display="true"]{overflow-x:auto;overflow-y:hidden;max-width:100%;padding-block:2px}

/* Desmos calculator panel */
.calc-btn svg{flex:none}
.calc-btn[aria-pressed="true"]{background:var(--ink);color:var(--paper);border-color:var(--ink)}
.q-meta .qtools{margin-left:auto;display:flex;gap:6px;flex-wrap:wrap}
.q-meta .qtools .flag{margin-left:0}
.q-meta .q-calc{padding:4px 10px;font-size:.82rem;font-weight:500}
.calc-panel{position:fixed;z-index:30;background:var(--surface);border-left:1px solid var(--line);display:flex;flex-direction:column;
  top:calc(var(--top-h,57px) + env(safe-area-inset-top,0px));right:0;bottom:0;width:min(46vw,640px)}
.calc-head{display:flex;justify-content:space-between;align-items:center;gap:10px;padding:8px 12px;border-bottom:1px solid var(--line)}
.calc-host{flex:1;min-height:0;position:relative;background:#fff}
.calc-foot{font-size:.72rem;color:var(--ink-2);padding:4px 12px;border-top:1px solid var(--line)}
@media (min-width:980px){
  body.calc-open .wrap,body.calc-open footer{margin-left:16px;margin-right:calc(min(46vw,640px) + 8px);max-width:none}
  body.calc-open .home-grid,body.calc-open .intro,body.calc-open .res-grid,body.calc-open .rv-grid{grid-template-columns:minmax(0,1fr)}
}
@media (max-width:979px){
  .calc-panel{top:0;left:0;width:auto;padding-top:env(safe-area-inset-top,0px);padding-bottom:env(safe-area-inset-bottom,0px);z-index:60}
  body.calc-open{overflow:hidden}
}

/* ---------- Math / English switch ---------- */
.nav .subj{display:inline-flex;border:1px solid var(--line);border-radius:999px;padding:2px;margin-right:6px;background:var(--surface)}
.nav .subj button{padding:5px 12px;border-radius:999px;font-weight:600;font-size:.88rem}
.nav .subj button[aria-pressed="true"]{background:var(--ink);color:var(--paper)}

/* ---------- Reading & Writing passages ---------- */
.q-pass{font-family:var(--f-read);font-size:1.08rem;line-height:1.7;max-width:65ch;margin-bottom:16px;padding:14px 16px;border-left:3px solid var(--line);background:var(--paper);border-radius:0 10px 10px 0}
.q-pass p{white-space:pre-line}
.q-pass p+p,.q-pass p+figure,.q-pass figure+p{margin-top:10px}
.ptable{margin:0;overflow-x:auto}
.ptable figcaption{font-family:var(--f-ui);font-size:.85rem;font-weight:600;margin-bottom:6px}
.ptable table{border-collapse:collapse;font-family:var(--f-ui);font-size:.92rem}
.ptable th,.ptable td{border:1px solid var(--line);padding:5px 10px;text-align:left}
.ptable th{background:var(--surface)}
@media (min-width:980px){
  .q.rw{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);column-gap:28px;align-items:start}
  .q.rw>*{grid-column:2}
  .q.rw>.q-meta{grid-column:1/-1}
  .q.rw>.q-pass{grid-column:1;grid-row:2/span 20;margin-bottom:0}
  body.calc-open .q.rw{display:block}
}
.rlist .body .q-pass{font-size:.98rem}
.samples{display:grid;gap:18px}

/* ---------- Tests page ---------- */
.tgrid{display:grid;grid-template-columns:repeat(auto-fill,minmax(190px,1fr));gap:12px}
.tcard{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:14px 16px;display:grid;gap:6px;align-content:start}
.tcard b{font-family:var(--f-display);font-size:1.15rem}
.tcard .btn{justify-self:start;margin-top:4px}
.fcard .rx{font-family:var(--f-read);font-size:.98rem;font-style:italic}

/* ---------- Content protection: question text can't be selected/copied with the mouse ---------- */
.q-stem,.q-pass,.choices,.expl,.ilist .st{-webkit-user-select:none;user-select:none}
.spr-in,textarea,input{-webkit-user-select:text;user-select:text}

/* Pre-SAT path */
.unit{margin-bottom:26px}
.tgrid.path{grid-template-columns:repeat(auto-fill,minmax(210px,1fr))}
.tcard .stars{color:var(--warn);font-size:1.05rem;letter-spacing:2px}
.tcard.next{border-color:var(--accent);box-shadow:0 0 0 2px var(--accent) inset}
.tcard.done{background:var(--good-bg);border-color:var(--good)}
.tcard .track{margin:2px 0}

/* question graphs */
.qfig{margin:0 0 14px;max-width:340px}
.qgraph{width:100%;height:auto;display:block;background:var(--surface);border:1px solid var(--line);border-radius:10px}
.qgraph .gg{stroke:var(--line);stroke-width:1}
.qgraph .ga{stroke:var(--ink);stroke-width:1.6}
.qgraph .gl1{stroke:var(--accent);stroke-width:2.4;stroke-linecap:round}
.qgraph .gp{fill:var(--accent);stroke:var(--surface);stroke-width:1.5}
.qgraph .gt{fill:var(--ink-2);font:500 11px var(--f-ui)}
.qgraph .gt.gl{fill:var(--ink);font-style:italic;font-size:12px}
/* homework */
.hwlist{display:grid;gap:12px}
.hwcard{display:flex;flex-wrap:wrap;gap:10px 18px;align-items:center;justify-content:space-between;background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:14px 18px}
.hwcard b{font-family:var(--f-display);font-size:1.1rem;display:block}
.hwcard .st{font-size:.85rem;font-weight:600;border-radius:99px;padding:3px 10px;background:var(--warn-bg);color:var(--warn)}
.hwcard .st.done{background:var(--good-bg);color:var(--good)} .hwcard .st.late{background:var(--bad-bg);color:var(--bad)}
.hwres li{display:grid;gap:4px;padding:12px 0;border-bottom:1px solid var(--line);list-style:none}
.hwres .ok{color:var(--good);font-weight:600} .hwres .no{color:var(--bad);font-weight:600}
.memlist{display:grid;gap:4px;max-height:320px;overflow:auto;border:1px solid var(--line);border-radius:10px;padding:8px 12px;margin:8px 0}
.memlist label{display:flex;gap:8px;align-items:center;font-size:.9rem}
.memlist input{width:auto}

/* ---------- Growth: landing, dashboard, skills, sessions, challenge ---------- */
.btn.lg{padding:14px 24px;font-size:1.05rem;border-radius:12px}
.hero-l h1{max-width:20ch}
.hero-l .cta{margin-top:4px}
.benefits{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:12px;margin:6px 0 30px}
.benefit{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:14px;display:grid;gap:2px}
.benefit .bi{font-size:1.3rem}
.benefit b{font-family:var(--f-display);font-size:1.02rem}
.benefit span:last-child{font-size:.85rem;color:var(--ink-2)}
.how{margin:0 0 30px}
.how h2{font-size:1.35rem;margin-bottom:12px}
.how-steps{list-style:none;counter-reset:s;margin:0;padding:0;display:grid;grid-template-columns:repeat(auto-fit,minmax(170px,1fr));gap:12px}
.how-steps li{counter-increment:s;border-left:3px solid var(--hi);padding:4px 12px;display:grid}
.how-steps li b::before{content:counter(s) ". ";color:var(--ink-2)}
.how-steps span{font-size:.88rem;color:var(--ink-2)}
.trust{margin:26px 0 18px;display:grid;gap:6px}
.dash-top{display:flex;flex-wrap:wrap;justify-content:space-between;align-items:flex-end;gap:10px;margin-bottom:16px}
.dash-top h1{font-size:clamp(1.6rem,4vw,2.2rem);font-weight:800}
.badges{display:flex;gap:8px;flex-wrap:wrap}
.badge{background:var(--surface);border:1px solid var(--line);border-radius:99px;padding:6px 12px;font-weight:600;font-size:.9rem}
.hero-card{margin-bottom:20px;display:grid;gap:10px}
.hero-card h2{font-size:1.4rem}
.score .big.sm{font-size:clamp(1.6rem,5vw,2.2rem)}
.big-track{height:12px}
.big-track i{background:var(--hi)}
.gap{font-size:1.05rem}
.dash-grid{display:grid;grid-template-columns:minmax(0,1.6fr) minmax(0,1fr);gap:20px;align-items:start}
.dash-main{display:grid;gap:20px}
@media (max-width:860px){.dash-grid{grid-template-columns:minmax(0,1fr)}}
.plist{list-style:none;margin:14px 0 0;padding:0;display:grid;gap:10px}
.plist li{display:grid;grid-template-columns:28px minmax(0,1fr) auto;gap:10px;align-items:center;padding:10px;border:1px solid var(--line);border-radius:10px}
.plist li div{display:grid}
.plist li.next{border-color:var(--accent);box-shadow:0 0 0 1px var(--accent) inset}
.plist li.done{opacity:.7}
.pchk{width:24px;height:24px;border-radius:50%;border:1.5px solid var(--ink-2);display:grid;place-items:center;font-size:.8rem;font-weight:700}
.plist li.done .pchk{background:var(--good);border-color:var(--good);color:var(--surface)}
.weak{margin:0 0 14px;padding:0;list-style:none;display:grid;gap:10px}
.weak li{display:flex;justify-content:space-between;align-items:center;gap:10px}
.weak li div{display:grid}
.trend{margin-top:12px;font-size:.95rem}
.kpi b.up{color:var(--good)}
.goal-card select{padding:4px 8px}
.achs{display:flex;flex-wrap:wrap;gap:6px}
.ach{font-size:.8rem;padding:4px 10px;border-radius:99px;border:1px dashed var(--line);color:var(--ink-2)}
.ach.on{border:1px solid var(--hi);background:var(--hi);color:var(--hi-ink);font-weight:600}
.sbar{display:grid;grid-template-columns:minmax(0,1fr) minmax(80px,200px) auto;gap:14px;align-items:center;margin-bottom:14px;padding:12px 16px}
@media (max-width:600px){.sbar{grid-template-columns:minmax(0,1fr) auto}.sbar .track{grid-column:1/-1;grid-row:2}}
.next-up{margin-top:20px;display:grid;gap:8px}
.next-up h2{font-size:1.3rem}
.tests{margin-top:10px;color:var(--ink-2)}
.xp{font-weight:600}
.pill.st-good,.st-good{background:var(--good-bg);color:var(--good)}
.pill.st-mid,.st-mid{background:var(--warn-bg);color:var(--warn)}
.pill.st-low,.st-low{background:var(--bad-bg);color:var(--bad)}
.pill.st-new,.st-new{background:var(--paper);color:var(--ink-2);border:1px solid var(--line)}
.track i.st-good{background:var(--good)} .track i.st-mid{background:#D99A00} .track i.st-low{background:var(--bad)} .track i.st-new{background:var(--line)}
.legend3{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:14px}
.legend3 span{font-size:.8rem;font-weight:600;padding:3px 10px;border-radius:99px}
.skillsec{margin-bottom:16px}
.mlist{list-style:none;margin:0;padding:0;display:grid;gap:12px}
.mlist li{display:grid;grid-template-columns:minmax(0,1.6fr) minmax(90px,1fr) 118px auto;gap:12px;align-items:center}
.mname{display:grid}
.mbar{display:flex;gap:8px;align-items:center}
.mbar .track{flex:1}
@media (max-width:700px){.mlist li{grid-template-columns:minmax(0,1fr) auto;row-gap:6px}.mlist .mbar{grid-column:1/-1}.mlist .pill{justify-self:start}}
.ob{display:grid;gap:14px;max-width:760px}
.obq{border:1px solid var(--line);border-radius:12px;background:var(--surface);padding:12px 16px 16px;margin:0}
.obq legend{font-weight:600;padding:0 6px;display:flex;gap:8px;align-items:center}
.obn{width:22px;height:22px;border-radius:50%;background:var(--ink);color:var(--paper);display:inline-grid;place-items:center;font-size:.75rem}
.chip.lg{padding:9px 16px;font-size:.95rem;min-height:42px}
.steps{margin:0;padding-left:20px;display:grid;gap:12px}
.steps li span{display:block;color:var(--ink-2);font-size:.9rem}
.profile .gap{margin-top:6px}
h2.h3{font-size:1.1rem;margin-bottom:10px}
.ticks{list-style:none;margin:0;padding:0;display:grid;gap:8px;font-weight:600}
.ticks.good li{color:var(--good)} .ticks.warn li{color:var(--warn)}
.chal-bar{margin-bottom:10px}
.chal-t{font-size:1.3rem}
.chal-res{margin-top:16px;display:grid;gap:8px}
.chal-res h2{font-size:1.25rem}
.stat-line{font-weight:600}
.share{display:grid;gap:6px;margin-top:6px}
/* mobile: one swipeable nav row, bigger touch targets */
@media (max-width:700px){
  .top-in{flex-wrap:wrap}
  .nav{flex-wrap:nowrap;overflow-x:auto;width:100%;-webkit-overflow-scrolling:touch;scrollbar-width:none;padding-bottom:2px}
  .nav::-webkit-scrollbar{display:none}
  .nav button,.nav a{flex:none;white-space:nowrap}
  .nav button.gsi-top{margin-left:auto}
  .ch{min-height:52px}
  .q{padding:16px}
  .q-actions .btn{flex:1 1 auto}
  .wrap{padding-block:18px 48px}
}
.dash-main .kpis{grid-template-columns:repeat(auto-fit,minmax(115px,1fr));margin-bottom:8px}.dash-main .kpi b{font-size:1.35rem}
/* ---- classes (teachers + students) */
.teach-cta{display:flex;gap:16px;align-items:center;justify-content:space-between;flex-wrap:wrap;margin:24px 0}
.teach-cta h2{margin:4px 0 6px}
.code-big{font-size:clamp(2rem,10vw,3.2rem);font-weight:700;letter-spacing:.22em;margin:6px 0 4px;color:var(--ink)}
.code-chip{font-size:.85rem;letter-spacing:.12em;border:1px solid var(--line);border-radius:8px;padding:3px 8px;white-space:nowrap}
.invite{margin-bottom:18px}
.invite-link{background:var(--paper);border:1px solid var(--line);border-radius:8px;padding:8px 10px;margin:8px 0 12px;overflow-wrap:anywhere}
.cls-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:14px}
.cls-card h2{font-size:1.1rem;margin:0}
.cls-card p{min-height:1.2em}
.cls-new{display:grid;gap:4px;place-content:center;text-align:center;border-style:dashed;cursor:pointer;min-height:140px;font:inherit;color:inherit}
.cls-new:hover{border-color:var(--ink-2)}
.ctabs{display:flex;gap:6px;margin:20px 0 12px;flex-wrap:wrap}
.ctabs button{border:1px solid var(--line);background:var(--surface);border-radius:99px;padding:7px 14px;cursor:pointer;font:inherit;font-size:.9rem;color:inherit;min-height:40px}
.ctabs button[aria-pressed="true"]{background:var(--ink);color:var(--paper);border-color:var(--ink)}
.roster tr.click{cursor:pointer}
.roster tr.click:hover td,.roster tr.click:focus td{background:var(--paper)}
.warn-t{color:var(--warn);font-weight:600}
.join-row{gap:8px;flex-wrap:nowrap}
.code-in{font-family:var(--f-mono);text-transform:uppercase;letter-spacing:.15em;padding:8px 10px;border:1px solid var(--line);border-radius:8px;width:9.5em;min-width:0;flex:1 1 auto;background:var(--surface);color:var(--ink);font-size:1rem}
.cls-mine{list-style:none;padding:0;margin:8px 0 10px;display:grid;gap:8px}
.cls-mine li{display:flex;justify-content:space-between;align-items:center;gap:8px}
.cls-mine li div{display:grid;min-width:0}
.join-list{margin:6px 0 16px;padding-left:1.2em;line-height:1.8}
.join-card{max-width:640px;margin:24px auto}
.join-card h1{margin:6px 0 10px}
.hwmini{list-style:none;padding:0;margin:0;display:grid;gap:10px}
.hwmini li{display:flex;justify-content:space-between;align-items:center;gap:10px;flex-wrap:wrap}
.hwmini .st{font-size:.85rem;font-weight:600;border-radius:99px;padding:3px 10px;background:var(--warn-bg);color:var(--warn)}
.hwmini .st.done{background:var(--good-bg);color:var(--good)} .hwmini .st.late{background:var(--bad-bg);color:var(--bad)}
.plain-ch{margin:8px 0;padding:0;list-style:none;display:grid;gap:4px}
.plain-ch li{padding:6px 10px;border:1px solid var(--line);border-radius:8px;border-bottom:1px solid var(--line)!important}
.plain-ch li.right{border-color:var(--good);background:var(--good-bg)}
details.expl summary{cursor:pointer;font-weight:600}
.h3s{font-size:1rem;margin:18px 0 8px}
.btn.danger{color:var(--bad)}
/* ---- graph extras: shading, dashed boundaries, number lines */
.qgraph .gfill{fill:var(--accent);opacity:.14}
.qgraph .gdash{stroke-dasharray:7 5}
.qfig-nl{max-width:480px}
.qgraph .nla{fill:var(--ink)}
.qgraph .nlseg{stroke:var(--accent);stroke-width:5;stroke-linecap:butt}
.qgraph .nlarr{fill:var(--accent)}
.qgraph .nldot{fill:var(--accent);stroke:var(--accent);stroke-width:2}
.qgraph .nlopen{fill:var(--surface);stroke:var(--accent);stroke-width:2.5}
/* ---- exam mode */
.exgrid{display:grid;grid-template-columns:repeat(auto-fill,minmax(40px,1fr));gap:6px;margin:6px 0 16px}
.exgrid button{min-height:40px;border:1px solid var(--line);background:var(--surface);border-radius:8px;font:600 .9rem var(--f-mono);color:var(--ink-2);cursor:pointer}
.exgrid button.on{background:var(--accent);border-color:var(--accent);color:#fff}
.exgrid button.cur{outline:3px solid var(--ink);outline-offset:1px}
.exnav{margin-top:14px}

/* worksheets */
.ws-card{position:relative}
.ws-ic{display:inline-block;font:700 .72rem/1 system-ui,sans-serif;color:#fff;background:#dc2626;border-radius:4px;padding:4px 6px;width:max-content}

/* landing: "Where are you starting from?" */
.paths-hero{text-align:center;display:grid;gap:10px;justify-items:center;margin:8px 0 22px}
.paths-hero h1{font-size:clamp(2rem,5.4vw,3.4rem);font-weight:800;letter-spacing:-.025em;max-width:20ch}
.ph-sub{font-family:var(--f-read);font-size:1.15rem;color:var(--ink-2)}
.ph-ar{font-size:1.1rem;font-weight:700;color:var(--accent)}
.paths{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin-bottom:30px}
.path{display:flex;flex-direction:column;gap:8px;align-items:flex-start;background:var(--surface);border:1.5px solid var(--line);border-radius:16px;padding:22px}
.path h2{font-size:1.35rem}
.path p{color:var(--ink-2);font-size:.95rem;flex:1}
.path .btn{border-radius:999px;margin-top:6px}
.path:not(.hot) .btn{border:1.5px solid var(--ink)}
.path.hot{border-color:var(--accent);box-shadow:0 10px 28px rgba(50,77,199,.16)}
.path-ic{font-size:1.9rem;line-height:1}
.path-note{font-size:.8rem;color:var(--ink-2)}
@media (max-width:760px){.paths{grid-template-columns:1fr}.path.hot{order:-1}}

/* WhatsApp online-session buttons */
.wa-btn{background:#25D366;color:#fff;border-color:#25D366;border-radius:999px;font-weight:700}
.wa-btn:hover{background:#1ebe5b;border-color:#1ebe5b}
.wa-ic{font-size:1em;line-height:1}
.wa-line{display:flex;flex-wrap:wrap;gap:10px;align-items:center;justify-content:center;margin:-12px 0 28px;color:var(--ink-2)}
.wa-help{display:flex;flex-wrap:wrap;gap:10px;align-items:center;justify-content:space-between;margin-top:14px;padding-top:12px;border-top:1px dashed var(--line);color:var(--ink-2)}

.wa-tag{background:#fff;color:#128C4A;border-radius:999px;padding:1px 8px;font-size:.75rem;font-weight:800;margin-left:2px}
.wa-fab{position:fixed;right:18px;bottom:18px;z-index:60;display:flex;align-items:center;gap:10px;background:#25D366;color:#fff;border:0;border-radius:999px;padding:10px 18px 10px 14px;box-shadow:0 8px 24px rgba(0,0,0,.22);cursor:pointer;font:inherit}
.wa-fab:hover{background:#1ebe5b}
.wa-fab .wa-ic svg{width:28px;height:28px}
.wa-fab-t{display:flex;flex-direction:column;line-height:1.1;text-align:left}
.wa-fab-t b{font-size:.95rem}.wa-fab-t small{font-size:.72rem;opacity:.9}
.wa-foot{font-weight:700;color:#128C4A}
@media (max-width:600px){.wa-fab{right:12px;bottom:12px;padding:9px 14px 9px 11px}.wa-fab .wa-ic svg{width:24px;height:24px}}