@font-face{font-family:"Newsreader";font-style:normal;font-weight:300 700;font-display:swap;src:url("fonts/newsreader-latin.woff2") format("woff2");unicode-range:U+0000-00FF,U+2013-2014,U+2018-201E,U+2022,U+2026,U+2212,U+00B0,U+00B7,U+2192,U+2194,U+2195,U+21BA,U+221A,U+03C3}
@font-face{font-family:"Newsreader";font-style:normal;font-weight:300 700;font-display:swap;src:url("fonts/newsreader-latin-ext.woff2") format("woff2");unicode-range:U+0100-024F,U+0218-021B,U+1E00-1EFF,U+20AC}
@font-face{font-family:"Newsreader";font-style:italic;font-weight:400;font-display:swap;src:url("fonts/newsreader-italic-400-latin.woff2") format("woff2");unicode-range:U+0000-00FF,U+2013-2014,U+2018-201E,U+2026,U+2212}
@font-face{font-family:"Newsreader";font-style:italic;font-weight:400;font-display:swap;src:url("fonts/newsreader-italic-400-latin-ext.woff2") format("woff2");unicode-range:U+0100-024F,U+0218-021B,U+1E00-1EFF}
@font-face{font-family:"Plex";font-style:normal;font-weight:300 700;font-display:swap;src:url("fonts/IBMPlexSans-latin.woff2") format("woff2");unicode-range:U+0000-00FF,U+0131,U+0152-0153,U+02C6,U+02DA,U+02DC,U+2000-206F,U+20AC,U+2122,U+2190-2195,U+21BA,U+2212,U+2215,U+221A,U+FEFF}
@font-face{font-family:"Plex";font-style:normal;font-weight:300 700;font-display:swap;src:url("fonts/IBMPlexSans-latin-ext.woff2") format("woff2");unicode-range:U+0100-02AF,U+0304,U+0308,U+0329,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF}

/* light: a squared maths exercise book, blue ink and the teacher's red pen.
   dark: a school blackboard, chalk. */
:root{
  --bg:#f6f3ea;--paper:#fbf9f3;--grid:rgba(60,100,185,.13);--margin:rgba(196,52,40,.42);
  --fg:#14182a;--mut:#3b4055;--line:#b7b7c4;--line-soft:#dcdbe2;
  --ink:#1f3b8f;--ink-soft:rgba(31,59,143,.16);--red:#a81f16;--red-soft:rgba(168,31,22,.12);--hi:#a81f16;
  --band:rgba(31,59,143,.2);--band-line:rgba(31,59,143,.42);--dot:rgba(20,24,42,.30);--pass:#1f3b8f;--fail:#a81f16;
  --serif:"Newsreader",Georgia,serif;--sans:"Plex",system-ui,-apple-system,"Segoe UI",sans-serif;
  --top:46px;color-scheme:light;--to-top-bg:#fbf9f3;--to-top-fg:#14182a;--sq:11px;
}
:root[data-theme=dark]{
  --bg:#17201c;--paper:#1c2722;--grid:rgba(236,235,226,.055);--margin:rgba(255,155,143,.30);
  --fg:#ecebe2;--mut:#c9cbbf;--line:#56635c;--line-soft:#2c3933;
  --ink:#c3d1ff;--ink-soft:rgba(195,209,255,.16);--red:#ffa196;--red-soft:rgba(255,161,150,.13);--hi:#ffd27a;
  --band:rgba(236,235,226,.09);--band-line:rgba(236,235,226,.42);--dot:rgba(236,235,226,.55);--pass:#e9e7db;--fail:#ff8f80;
  color-scheme:dark;--to-top-bg:#1c2722;--to-top-fg:#ecebe2;
}
*{box-sizing:border-box}[hidden]{display:none!important}svg[hidden]{display:none}
html{scroll-padding-top:calc(var(--top) + 14px);-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--fg);font:400 1.125rem/1.62 var(--serif);
  background-image:linear-gradient(var(--grid) 1px,transparent 1px),linear-gradient(90deg,var(--grid) 1px,transparent 1px);background-size:22px 22px;background-position:-1px -1px}
a{color:var(--ink);text-underline-offset:.18em;text-decoration-thickness:1px}
button,input{font:inherit;color:inherit}
:focus-visible{outline:2px solid var(--hi);outline-offset:2px}
.skip-link{position:absolute;left:-999px}.skip-link:focus{left:8px;top:8px;z-index:99;background:var(--bg);padding:.5rem .8rem}
.sr{position:absolute!important;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}

/* topbar, progress, rail */
.topbar{position:sticky;top:0;z-index:50;background:var(--bg);height:calc(var(--top) + var(--browser-safe-top,env(safe-area-inset-top)));padding:var(--browser-safe-top,env(safe-area-inset-top)) .9rem 0;display:flex;align-items:center;gap:.4rem;border-bottom:1px solid var(--line-soft);font-family:var(--sans)}
.topbar a{color:inherit;text-decoration:none}
.brand{display:flex;align-items:center;gap:.45rem;white-space:nowrap;font-weight:500;font-size:.95rem}
.brand-mark{width:22px;height:22px}.m-pass{fill:var(--pass)}.m-fail{stroke:var(--fail);stroke-width:2.2;stroke-linecap:round;fill:none}
.topnav{display:flex;gap:1rem;overflow-x:auto;scrollbar-width:none;margin-left:.8rem;color:var(--mut)}.topnav::-webkit-scrollbar{display:none}
.topnav a{white-space:nowrap;font-size:.85rem}.topnav a:hover{color:var(--fg)}
.spacer{flex:1}
.chip{font:500 .75rem/1 var(--sans);padding:.4rem .55rem;border:1px solid var(--line);border-radius:99px;min-height:30px;display:inline-flex;align-items:center}
.chip[aria-current=page]{border-color:var(--fg)}
.icon-btn{background:none;border:1px solid var(--line);border-radius:99px;width:34px;height:34px;display:grid;place-items:center;cursor:pointer;color:var(--fg)}
:root[data-theme=light] .i-moon,:root[data-theme=dark] .i-sun{display:none}
@media (max-width:1100px){.topnav{display:none}}
@media (max-width:380px){.brand span{display:none}}
.progress{position:fixed;left:0;right:0;top:calc(var(--top) + var(--browser-safe-top,env(safe-area-inset-top)));height:2px;z-index:49;pointer-events:none}
.progress i{display:block;height:2px;width:100%;background:var(--red);transform-origin:0 50%;transform:scaleX(0)}
.rail{position:fixed;right:10px;top:50%;transform:translateY(-50%);z-index:30;display:flex;flex-direction:column;gap:9px;opacity:0;transition:opacity .3s}
.rail.on{opacity:1}
.rail-dot{position:relative;display:block;width:12px;height:12px}
.rail .dot{position:absolute;inset:3px;border-radius:2px;background:var(--line);transition:background .2s}
.rail-dot[aria-current=true] .dot{background:var(--ink)}
.rail-label{position:absolute;right:18px;top:50%;transform:translateY(-50%);white-space:nowrap;font:400 .76rem var(--sans);background:var(--paper);border:1px solid var(--line);padding:.15rem .45rem;border-radius:6px;opacity:0;pointer-events:none;transition:opacity .15s;color:var(--fg)}
.rail-dot:hover .rail-label,.rail-dot:focus-visible .rail-label{opacity:1}
@media (max-width:1360px){.rail{display:none}}

/* layout */
main{display:block}
.prose{max-width:41rem;margin:0 auto;padding:0 1rem}
.wide{max-width:64rem;margin:1.4rem auto;padding:0 1rem}
.ch{padding:3.2rem 0 1rem}
h1,h2,h3{font-weight:600;line-height:1.16;letter-spacing:-.012em}
h2{font-size:clamp(1.45rem,3.2vw,1.95rem);margin:0 0 .8rem}
h3{font-size:1.2rem}
.anchor{margin-left:.4rem;font:400 .8em var(--sans);color:var(--line);text-decoration:none;opacity:0}
h2:hover .anchor,.anchor:focus{opacity:1}
.lbl{font:600 .78rem/1.3 var(--sans);letter-spacing:.04em;text-transform:uppercase;color:var(--mut);margin:.2rem 0 .5rem;display:block}
.hint,.note{font:400 .9rem/1.5 var(--sans);color:var(--mut)}
.btn{font:500 .92rem/1 var(--sans);border:1.5px solid var(--fg);background:var(--paper);border-radius:8px;padding:.62rem .95rem;cursor:pointer;min-height:44px}
.btn.primary{background:var(--ink);border-color:var(--ink);color:var(--paper)}
.btn:hover{border-color:var(--ink)}

/* hero */
.hero{padding:clamp(1.6rem,5vw,3.6rem) 0 1rem}
.hero-in{max-width:52rem;margin:0 auto;padding:0 1rem}
.kicker{font:600 .8rem/1.3 var(--sans);letter-spacing:.06em;text-transform:uppercase;color:var(--red);margin:0 0 .7rem}
h1{font-size:clamp(1.9rem,5.2vw,3.15rem);margin:0 0 1rem;max-width:22ch}
.deck{font-size:clamp(1.12rem,2.2vw,1.32rem);line-height:1.5;color:var(--mut);max-width:40rem;margin:0}

/* hero: text beside the picture on wide screens */
.hero-grid{max-width:76rem;margin:0 auto;display:grid;gap:1.2rem 2.4rem;align-items:start}
@media (min-width:1100px){.hero-grid{grid-template-columns:minmax(0,.95fr) minmax(0,1.05fr);padding:0 1rem}.hero-grid .hero-in{padding:0}.hero-grid .sheet{margin-top:.3rem}h1{font-size:clamp(2rem,3.4vw,2.9rem)}}
.tiles{list-style:none;margin:1rem 0 .4rem;padding:0;display:flex;flex-wrap:wrap;gap:12px 14px;align-items:flex-end;--sq:14px}
.tile{display:flex;flex-direction:column;align-items:flex-start;gap:4px}
.tile .sq{max-width:calc(5 * (var(--sq) + 3px));}
.tile b{font:600 .78rem/1 var(--sans);color:var(--fail)}
.tiles.drawn .tile{animation:pop .45s ease both}
.typical .tlab{font:600 .95rem var(--sans);margin:0 0 .5rem;grid-column:1/-1}
.typical .tsub{grid-column:1/-1;margin:.5rem 0 0;font:400 .82rem var(--sans);color:var(--mut)}
.typical{--sq:14px}.typical .sq{max-width:calc(15 * (var(--sq) + 3px))}
.sheet-2{margin-top:1.2rem}
@media (min-width:1100px){.sheet-2{max-width:74rem}}
.zl-h{font-size:1.05rem;margin:1.4rem 0 .2rem}
@media (max-width:640px){.tiles{--sq:12px;gap:10px 12px}.typical{--sq:12px}}
/* the sheet: a page of the exercise book */
.sheet{max-width:64rem;margin:1.8rem auto 0;background:var(--paper);border:1px solid var(--line-soft);border-radius:4px;
  padding:1.3rem 1.2rem 1.4rem 3.1rem;position:relative;box-shadow:0 1px 0 var(--line-soft),0 14px 40px -26px rgba(20,24,42,.35)}
.sheet::before{content:"";position:absolute;left:2.1rem;top:0;bottom:0;width:1.5px;background:var(--margin)}
@media (max-width:640px){.sheet{margin:1.4rem .5rem 0;padding:1rem .8rem 1.2rem 1.7rem}.sheet::before{left:1rem}}
.sheet figcaption{display:flex;flex-wrap:wrap;gap:.4rem 1.4rem;align-items:baseline;justify-content:space-between}
.sheet-h{font-size:1.18rem;margin:0}
.legend{display:flex;gap:1rem;font:400 .82rem var(--sans);color:var(--mut);margin:0}
.legend span{display:inline-flex;align-items:center;gap:.35rem}
.sq{display:flex;flex-wrap:wrap;gap:3px;align-items:center}
.sq i,.legend i{display:inline-block;width:var(--sq);height:var(--sq);border-radius:1.5px;flex:none}
i.p{background:var(--pass)}
i.f{border:1.5px solid var(--fail);background:linear-gradient(45deg,transparent 42%,var(--fail) 42%,var(--fail) 58%,transparent 58%),linear-gradient(-45deg,transparent 42%,var(--fail) 42%,var(--fail) 58%,transparent 58%)}
.typical{display:block;margin:1.2rem 0 .2rem;padding-top:1rem;border-top:1px dashed var(--line)}
.typical b{font:500 .86rem/1.35 var(--sans)}
.zlist{list-style:none;margin:.5rem 0 0;padding:0;counter-reset:z}
.zr{display:grid;grid-template-columns:minmax(10rem,19rem) 6.2rem 1fr;gap:.2rem 1rem;align-items:center;padding:.32rem 0;border-bottom:1px solid var(--line-soft)}
.zl{display:flex;flex-direction:column;line-height:1.25}
.zl b{font:500 .9rem/1.3 var(--sans)}
.zr:not(.named) .zl b{font-weight:400;color:var(--mut)}
.zl span{font:400 .78rem var(--sans);color:var(--mut)}
.zn{font:500 .84rem var(--sans);color:var(--red);white-space:nowrap}
.zlist.drawn .zr{animation:pop .45s ease both}
.zlist.drawn .zr:nth-child(n+6){animation-delay:.04s}
@keyframes pop{from{opacity:0;transform:translateY(4px)}to{opacity:1;transform:none}}
@media (max-width:640px){.zr{grid-template-columns:1fr auto;}.zr .sq{grid-column:1/-1}}
.draw{margin:1rem 0 .4rem;padding:.9rem 1rem;background:var(--ink-soft);border-radius:6px}
@media (min-width:1100px){.zlist{column-count:2;column-gap:2.4rem}.zr{break-inside:avoid}.zr{grid-template-columns:minmax(9rem,15rem) 5.6rem 1fr}}
.draw-lead{margin:0 0 .8rem;font-size:1.02rem}
.draw-btns{display:flex;gap:.6rem;flex-wrap:wrap}
.draw-res{font:600 1rem/1.4 var(--sans);margin:.8rem 0 .2rem;color:var(--red)}
.press{border-left:3px solid var(--line);padding-left:.7rem;margin-top:1.2rem}

/* share row */
.share{margin:1rem 0 0}
.share-row{display:flex;align-items:center;gap:.45rem;flex-wrap:wrap}
.share-label{font:500 .82rem var(--sans);color:var(--mut);margin-right:.2rem}
.ic{width:40px;height:40px;border-radius:50%;border:1px solid var(--line-soft);display:grid;place-items:center;color:var(--fg);background:transparent;cursor:pointer;text-decoration:none}
.ic:hover,.ic:focus-visible{border-color:var(--ink);color:var(--ink)}
@media (pointer:coarse){.ic{width:44px;height:44px}}
.share-msg{font:400 .82rem var(--sans);color:var(--mut);min-height:1.2em;margin:.3rem 0 0}

/* school finder */
.finder{background:var(--paper);border:1px solid var(--line-soft);border-radius:4px;padding:1.2rem}
.qwrap{position:relative}
#q{width:100%;font:400 1.05rem var(--sans);padding:.75rem .9rem;border:1.5px solid var(--fg);border-radius:8px;background:var(--bg)}
.qlist{position:absolute;left:0;right:0;top:100%;z-index:20;list-style:none;margin:.25rem 0 0;padding:.25rem;background:var(--paper);border:1px solid var(--line);border-radius:8px;max-height:20rem;overflow:auto;box-shadow:0 12px 30px -18px rgba(0,0,0,.45)}
.qlist li{padding:.5rem .6rem;border-radius:6px;cursor:pointer;font:400 .92rem/1.3 var(--sans)}
.qlist li small{display:block;color:var(--mut);font-size:.78rem}
.qlist li[aria-selected=true],.qlist li:hover{background:var(--ink-soft)}
.exs{display:flex;flex-wrap:wrap;gap:.45rem;margin-top:.3rem}
.exb{font:400 .84rem var(--sans);border:1px solid var(--line);background:transparent;border-radius:99px;padding:.4rem .75rem;cursor:pointer;min-height:36px;text-align:left}
.exb:hover{border-color:var(--ink)}
.scard{margin-top:1.2rem;padding-top:1rem;border-top:1.5px solid var(--fg)}
.scard-head{display:grid;grid-template-columns:1fr auto;gap:.1rem 1rem;align-items:start}
.scard-head h3{margin:0;font-size:1.3rem}.scard-head .btn{grid-row:1/3;grid-column:2}
.where{margin:0;font:400 .9rem var(--sans);color:var(--mut)}
.schart{margin:.8rem 0 .4rem}
.schart svg{width:100%;height:auto;display:block;overflow:visible}
.verdict{font-size:1.08rem;margin:.6rem 0 .2rem}
.verdict b{font-weight:600}
svg text{font-family:var(--sans);fill:var(--mut)}
.ax{stroke:var(--line);stroke-width:1}
.bandp{fill:var(--band);stroke:var(--band-line);stroke-width:.8}
.sline{fill:none;stroke:var(--pass);stroke-width:2}
.spt{fill:var(--pass)}.spt.small{fill:var(--paper);stroke:var(--mut);stroke-width:1.5;stroke-dasharray:2 2}
.lbl-y{font-size:12px}.lbl-v{font-size:12.5px;fill:var(--fg);font-weight:500}

/* funnel */
.ffig{position:relative}
.fctl{display:flex;flex-wrap:wrap;gap:.5rem .8rem;align-items:center;margin-bottom:.6rem}
.ychips{display:flex;flex-wrap:wrap;gap:.3rem}
@media (max-width:640px){.ychips{flex-wrap:nowrap;overflow-x:auto;max-width:100%;scrollbar-width:thin;padding-bottom:4px}.ychip{flex:none}.fctl{flex-wrap:wrap}}
.ychip{font:400 .8rem var(--sans);border:1px solid var(--line);background:var(--paper);border-radius:6px;padding:.35rem .5rem;cursor:pointer;min-height:34px}
.ychip[aria-pressed=true]{background:var(--fg);color:var(--bg);border-color:var(--fg)}
.fyear{font:600 1.05rem var(--sans);color:var(--red);min-width:6rem}
.fwrap{position:relative;background:var(--paper);border:1px solid var(--line-soft);border-radius:4px}
#fcv{display:block;width:100%;height:min(68vh,560px);cursor:crosshair;touch-action:pan-y}
@media (max-width:640px){#fcv{height:min(56vh,420px)}}
.pop{position:absolute;z-index:10;min-width:13rem;max-width:18rem;background:var(--paper);border:1.5px solid var(--fg);border-radius:8px;padding:.6rem .7rem;font:400 .85rem/1.4 var(--sans);box-shadow:0 12px 30px -14px rgba(0,0,0,.45)}
.pop b{display:block;font-weight:600;font-size:.9rem;margin-bottom:.2rem}
.pop .btn{min-height:36px;padding:.4rem .6rem;font-size:.82rem;margin-top:.45rem}
.pop .x{position:absolute;right:.3rem;top:.2rem;border:0;background:none;font-size:1.1rem;cursor:pointer;color:var(--mut);min-width:32px;min-height:32px}
.axis-note{display:flex;justify-content:space-between;gap:1rem;flex-wrap:wrap;font:400 .82rem var(--sans);color:var(--mut);margin:.4rem 0 0}

/* bands table */
.tbl-wrap{overflow-x:auto}
.bands table{width:100%;border-collapse:collapse;font:400 .9rem/1.35 var(--sans);background:var(--paper)}
.bands th,.bands td{text-align:left;padding:.55rem .6rem;border-bottom:1px solid var(--line-soft);vertical-align:middle}
.bands thead th{font-weight:600;font-size:.78rem;color:var(--mut)}
.bands tbody th{font-weight:600;white-space:nowrap}
.bar{display:inline-block;width:6.5rem;height:9px;background:var(--line-soft);border-radius:2px;margin-right:.5rem;vertical-align:middle;position:relative;overflow:hidden}
.bar i{position:absolute;left:0;top:0;bottom:0;width:var(--w);background:var(--pass)}
.bar.swing i{background:var(--fail)}
@media (max-width:640px){.bar{width:3.6rem}}

/* equation */
.formula{font:500 clamp(2rem,6vw,3.2rem)/1.2 var(--serif);text-align:center;margin:1.4rem 0 .6rem;color:var(--ink);letter-spacing:.01em}.formula sub{font-size:.42em}
.eqchart svg{width:100%;height:auto;display:block}
.eqband{fill:var(--band)}.eqline{fill:none;stroke:var(--band-line);stroke-width:1.5}.eqmid{stroke:var(--ink);stroke-width:1.5;stroke-dasharray:4 4}

/* checker */
.checker{display:grid;grid-template-columns:1fr 1fr;gap:1rem;margin:1rem 0 .4rem}
@media (max-width:560px){.checker{grid-template-columns:1fr}}
.cg{border:1px solid var(--line);border-radius:8px;padding:.6rem .8rem;background:var(--paper);margin:0;display:flex;flex-wrap:wrap;gap:.5rem 1rem;align-items:center}
.cg legend{font:600 .8rem var(--sans);color:var(--mut);padding:0 .3rem}
.cg label{font:400 .92rem var(--sans);display:flex;align-items:center;gap:.4rem}
.cg input{width:5.2rem;font:500 1rem var(--sans);padding:.45rem .5rem;border:1.5px solid var(--fg);border-radius:6px;background:var(--bg);min-height:44px}
.cres{font-size:1.08rem;margin:.6rem 0 .3rem}

/* faq, sources, footer */
.qa{border-bottom:1px solid var(--line-soft);padding:.7rem 0}
.qa summary{cursor:pointer;font-weight:600}
.qa p{margin:.5rem 0 0}
.sources{font:400 .9rem/1.45 var(--sans);padding-left:1.1rem}
.sources li{margin:.3rem 0}
.srcnote{font:400 .9rem/1.55 var(--sans);color:var(--mut)}
.site-footer{display:flex;flex-wrap:wrap;gap:.6rem 1.4rem;justify-content:center;padding:2.4rem 1rem 3rem;font:400 .85rem var(--sans);color:var(--mut);border-top:1px solid var(--line-soft);margin-top:3rem}
.site-footer a{color:inherit}
@media (prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important;scroll-behavior:auto!important}}
@media print{.topbar,.rail,.progress,.share,.draw,.fctl{display:none}}