:root{
  --bg:#f5f8fc;--paper:#ffffff;--ink:#0c1726;--muted:#617086;--line:#dce4ee;
  --navy:#07131f;--navy2:#0c2236;--teal:#0f9d8a;--teal2:#32d4bd;--violet:#6b5cff;
  --orange:#ee6c3b;--gold:#e5a11a;--red:#d84a63;--soft-teal:#eafbf7;--soft-violet:#f0efff;
  --soft-orange:#fff3ec;--soft-blue:#eef7ff;--soft-gold:#fff8e7;--soft-red:#fff0f4;
  --shadow:0 18px 48px rgba(27,43,65,.09);--shadow2:0 8px 24px rgba(27,43,65,.07);
  --radius:24px;--radius-sm:16px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:linear-gradient(180deg,#f7faff 0,#f4f7fb 48%,#fff 100%);color:var(--ink);font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;line-height:1.58}
button,input,select{font:inherit}button{cursor:pointer}
.hero-shell{position:relative;overflow:hidden;background:radial-gradient(circle at 78% 16%,rgba(50,212,189,.2),transparent 24%),radial-gradient(circle at 68% 100%,rgba(107,92,255,.21),transparent 30%),linear-gradient(135deg,#06111c,#0a2137 58%,#07131f);color:white;border-bottom:1px solid rgba(255,255,255,.08)}
.hero-noise{position:absolute;inset:0;opacity:.16;background-image:radial-gradient(rgba(255,255,255,.28) .7px,transparent .8px);background-size:12px 12px;mask-image:linear-gradient(to right,transparent,black 25%,black 75%,transparent)}
.hero-inner{position:relative;max-width:1280px;margin:auto;padding:58px 24px 52px;display:grid;grid-template-columns:1.05fr .95fr;gap:40px;align-items:center}
.eyebrow,.section-kicker{font-size:.76rem;text-transform:uppercase;letter-spacing:.13em;font-weight:900}.eyebrow{color:#70f1db}.hero-copy h1{font-size:clamp(3rem,7vw,6.1rem);line-height:.9;letter-spacing:-.065em;margin:.45rem 0 1.25rem}.hero-copy h1 span{color:#70f1db}.hero-lead{font-size:1.18rem;max-width:760px;color:#dce8f7;margin:0 0 1.5rem}.hero-actions{display:flex;gap:12px;flex-wrap:wrap}.hero-badges{display:flex;flex-wrap:wrap;gap:8px;margin-top:18px}.hero-badges span{font-size:.78rem;color:#dbe9f8;border:1px solid rgba(255,255,255,.13);background:rgba(255,255,255,.05);padding:6px 9px;border-radius:999px}.hero-board{border:1px solid rgba(255,255,255,.13);background:rgba(255,255,255,.035);border-radius:30px;box-shadow:inset 0 1px 0 rgba(255,255,255,.06),0 32px 80px rgba(0,0,0,.2);padding:10px}.hero-board svg{width:100%;display:block}
.btn{border:0;border-radius:14px;padding:11px 16px;font-weight:850;display:inline-flex;align-items:center;justify-content:center;gap:8px;transition:.18s ease}.btn:hover{transform:translateY(-1px)}.btn-primary{color:white;background:linear-gradient(135deg,#25cdb4,#0f8e7d);box-shadow:0 10px 26px rgba(15,157,138,.26)}.btn-secondary{background:#fff;color:var(--ink);border:1px solid var(--line)}.btn-ghost{background:rgba(255,255,255,.07);color:#fff;border:1px solid rgba(255,255,255,.16)}.btn-danger{background:#fff1f4;color:#b52847;border:1px solid #f1b8c7}.btn-sm{padding:8px 11px;font-size:.88rem}.btn-wide{width:100%}
.main-nav{position:sticky;top:0;z-index:50;display:flex;overflow:auto;gap:7px;padding:10px max(10px,calc((100vw - 1280px)/2));background:rgba(255,255,255,.93);backdrop-filter:blur(16px);border-bottom:1px solid var(--line)}.nav-item{white-space:nowrap;border:0;background:transparent;color:#556479;font-weight:820;padding:10px 13px;border-radius:12px}.nav-item:hover{background:#f1f5f9}.nav-item.active{background:#0c1726;color:#fff}.nav-item.nav-special{border:1px solid #d8d4ff}.nav-item.nav-special.active{background:linear-gradient(135deg,#6b5cff,#5748eb);border-color:transparent}
.app-shell{max-width:1280px;margin:auto;padding:34px 22px 72px}.screen{display:none}.screen.active{display:block}.section-top{display:flex;justify-content:space-between;gap:28px;align-items:end;margin:8px 0 24px}.section-top>div{max-width:760px}.section-kicker{color:var(--orange)}.section-top h2{font-size:clamp(2.15rem,5vw,3.5rem);line-height:1;letter-spacing:-.045em;margin:.25rem 0 0}.section-top p{max-width:500px;color:var(--muted);margin:0}.section-intro{color:#45556d;font-size:1.02rem;max-width:920px}.math-block{display:flex;justify-content:center;align-items:center;overflow:auto;background:#f8fbfe;border:1px solid var(--line);border-radius:17px;padding:14px 16px;margin:13px 0}.math-block.dark{background:#0b1f31;border-color:#183954;color:white}.katex-display{margin:.25em 0}.katex{font-size:1.05em}
.learning-map{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px;margin:20px 0 28px}.learn-card{position:relative;background:#fff;border:1px solid var(--line);border-radius:20px;padding:18px;box-shadow:var(--shadow2);overflow:hidden}.learn-card::after{content:"";position:absolute;right:-20px;bottom:-32px;width:90px;height:90px;border-radius:50%;background:var(--soft-teal)}.learn-num{width:36px;height:36px;display:grid;place-items:center;border-radius:12px;background:#0b1c2c;color:#fff;font-weight:900;margin-bottom:12px}.learn-card h3{font-size:1rem;margin:0 0 6px}.learn-card p{font-size:.9rem;color:var(--muted);margin:0;position:relative;z-index:1}
.callout-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px;margin:18px 0}.callout{border:1px solid var(--line);border-radius:20px;padding:18px;background:#fff}.callout h3{margin:0 0 8px;font-size:1.02rem}.callout p{color:#516076;margin:.3rem 0}.callout.teal{background:var(--soft-teal);border-color:#a9eadf}.callout.violet{background:var(--soft-violet);border-color:#ccc7ff}.callout.orange{background:var(--soft-orange);border-color:#ffd1bd}.callout.blue{background:var(--soft-blue);border-color:#cbe5fa}.callout.gold{background:var(--soft-gold);border-color:#efd99c}.callout.red{background:var(--soft-red);border-color:#efc0cb}
.rule-banner{display:grid;grid-template-columns:auto 1fr;gap:14px;align-items:center;background:#0b1f31;color:white;border-radius:22px;padding:18px 20px;margin:20px 0}.rule-icon{width:50px;height:50px;display:grid;place-items:center;border-radius:16px;background:linear-gradient(135deg,#2fd7bf,#685bff);font-weight:950;font-size:1.2rem}.rule-banner h3{margin:0 0 4px}.rule-banner p{margin:0;color:#d5e5f3}
.chapter-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);padding:clamp(20px,3vw,32px);margin:18px 0}.chapter-grid{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(320px,.85fr);gap:20px}.chapter-card h3{font-size:1.5rem;margin:.1rem 0 .7rem;letter-spacing:-.02em}.chapter-card h4{font-size:1.08rem;margin:1.25rem 0 .5rem}.chapter-card p,.chapter-card li{color:#46566d}.formula-table{width:100%;border-collapse:separate;border-spacing:0;border:1px solid var(--line);border-radius:16px;overflow:hidden;margin:16px 0}.formula-table th,.formula-table td{padding:12px 13px;text-align:left;vertical-align:top;border-bottom:1px solid var(--line)}.formula-table th{background:#f7f9fc;font-size:.86rem;color:#415066}.formula-table tr:last-child td{border-bottom:0}.formula-table td:first-child{font-weight:760}
.step-list{counter-reset:item;list-style:none;padding:0;margin:14px 0}.step-list li{counter-increment:item;display:grid;grid-template-columns:38px 1fr;gap:11px;margin:13px 0;align-items:start}.step-list li::before{content:counter(item);width:32px;height:32px;display:grid;place-items:center;background:#0c1726;color:#fff;border-radius:11px;font-weight:900}.error-note,.tip-note{border-radius:16px;padding:14px 16px;margin:14px 0}.error-note{background:#fff0f2;border:1px solid #f4bec9;color:#7d2538}.tip-note{background:#edf9f7;border:1px solid #b7e9df;color:#24594f}
.mini-lab{background:linear-gradient(180deg,#fbfdff,#f5f8fc);border:1px solid var(--line);border-radius:22px;padding:16px}.mini-lab .mini-title{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:8px}.mini-lab .mini-title strong{font-size:.98rem}.mini-lab canvas{width:100%;height:auto;background:white;border:1px solid #e2e8f0;border-radius:14px;display:block}.mini-controls{display:grid;gap:10px;margin-top:12px}.mini-controls label{font-size:.84rem;font-weight:800;color:#4b5c73}.mini-controls input[type=range]{width:100%}.mini-value{display:inline-flex;min-width:50px;justify-content:center;background:#fff;border:1px solid var(--line);padding:4px 8px;border-radius:10px;font-weight:850}
.vector-card{background:#f8fbfe;border:1px solid var(--line);border-radius:20px;padding:15px}.vector-card svg{width:100%;height:auto;display:block}.caption{font-size:.86rem;color:var(--muted);margin-top:8px}.split-note{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}.split-note>div{border:1px solid var(--line);border-radius:16px;padding:14px;background:#fff}.split-note strong{display:block;margin-bottom:6px}
.special-hero{position:relative;overflow:hidden;background:linear-gradient(135deg,#0b1d2d,#132d49);color:#fff;border-radius:30px;padding:28px;box-shadow:0 24px 60px rgba(11,29,45,.19);margin-bottom:22px}.special-hero::after{content:"";position:absolute;width:260px;height:260px;right:-70px;top:-90px;border-radius:50%;background:radial-gradient(circle,rgba(66,231,205,.33),transparent 66%)}.special-hero .section-kicker{color:#7af0de}.special-hero h2{font-size:clamp(2.2rem,5vw,4rem);margin:.3rem 0 .7rem;letter-spacing:-.05em;line-height:1}.special-hero p{max-width:880px;color:#d7e8f7;margin:0}.special-formula{display:inline-flex;margin-top:16px;padding:10px 15px;border-radius:14px;background:rgba(255,255,255,.08);border:1px solid rgba(255,255,255,.14)}
.point-theory{display:grid;gap:12px;margin:18px 0}.theory-point{display:grid;grid-template-columns:54px 1fr;gap:15px;align-items:start;border:1px solid var(--line);background:#fff;border-radius:20px;padding:16px;box-shadow:var(--shadow2);transition:.18s}.theory-point:hover{transform:translateY(-1px);box-shadow:0 13px 34px rgba(27,43,65,.09)}.theory-point.active{border-color:#8b80ff;box-shadow:0 0 0 3px rgba(107,92,255,.11),var(--shadow2)}.point-num{width:45px;height:45px;display:grid;place-items:center;border-radius:14px;background:linear-gradient(135deg,#6b5cff,#4034cf);color:#fff;font-weight:950;font-size:1.05rem}.point-content h4{margin:0 0 5px;font-size:1.06rem}.point-content p{margin:.25rem 0;color:#52627a}.point-result{display:flex;gap:10px;flex-wrap:wrap;margin-top:8px}.formula-pill{display:inline-flex;align-items:center;background:#f6f8fb;border:1px solid var(--line);border-radius:11px;padding:7px 10px}
.special-lab-grid{display:grid;grid-template-columns:330px 1fr;gap:18px;margin:20px 0}.special-control-card,.special-graph-card{background:#fff;border:1px solid var(--line);border-radius:22px;box-shadow:var(--shadow2)}.special-control-card{padding:18px}.special-control-card h3{margin:.15rem 0 .55rem;font-size:1rem}.base-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px}.base-btn{border:1px solid var(--line);background:#fff;border-radius:12px;padding:10px;min-height:53px}.base-btn.active{background:#eafbf7;border-color:#66d7c5;box-shadow:inset 0 0 0 1px #66d7c5}.x-slider-wrap{border-top:1px solid var(--line);margin-top:14px;padding-top:14px}.x-slider-wrap input{width:100%}.point-readout{display:grid;gap:8px;margin-top:12px}.readout-row{display:flex;justify-content:space-between;gap:10px;align-items:center;border:1px solid var(--line);background:#f8fafc;border-radius:12px;padding:9px 10px;font-size:.88rem}.status-badge{font-size:.76rem;font-weight:900;padding:5px 8px;border-radius:999px}.status-good{background:#dff8f0;color:#166858}.status-warn{background:#fff1e8;color:#9e4c27}.status-bad{background:#ffecef;color:#a12c45}.special-graph-card{overflow:hidden}.graph-top{display:flex;justify-content:space-between;gap:12px;align-items:center;padding:13px 16px;background:#f8fafc;border-bottom:1px solid var(--line)}.graph-top span{font-size:.78rem;font-weight:900;text-transform:uppercase;letter-spacing:.08em;color:#69768a}.special-graph-card canvas{width:100%;height:auto;display:block;background:white}.graph-legend{display:flex;gap:15px;flex-wrap:wrap;padding:11px 15px;border-top:1px solid var(--line);font-size:.8rem;color:#607087}.legend-line{display:inline-block;width:23px;height:4px;border-radius:999px;margin-right:6px;vertical-align:middle}.legend-base{background:#8d9aa9}.legend-new{background:#0f9d8a}.legend-guide{background:#6b5cff}
.ordinate-map{display:grid;grid-template-columns:1fr auto 1fr;gap:14px;align-items:center;border:1px solid var(--line);background:#fff;border-radius:22px;padding:18px;margin:18px 0}.ordinate-box{border:1px solid var(--line);background:#f8fafc;border-radius:16px;padding:16px;text-align:center}.ordinate-box small{display:block;color:var(--muted);font-weight:800;margin-bottom:7px}.map-arrow{font-size:1.8rem;color:#6b5cff;font-weight:900}.ordinate-slider{grid-column:1/-1}.ordinate-slider input{width:100%}.ordinate-note{grid-column:1/-1;color:#4d5d74;font-size:.9rem;background:#f8fafc;border-radius:13px;padding:10px 12px}
.quick-consequences{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.consequence{background:#fff;border:1px solid var(--line);border-radius:17px;padding:14px}.consequence strong{display:block;margin-bottom:5px}.consequence p{margin:0;color:#596a80;font-size:.9rem}
.lab-layout{display:grid;grid-template-columns:360px 1fr;gap:18px}.control-panel,.graph-panel{background:#fff;border:1px solid var(--line);border-radius:22px;box-shadow:var(--shadow2)}.control-panel{padding:18px}.control-panel h3{font-size:1rem;margin:.1rem 0 .65rem}.control-panel select,.control-panel input[type=text],.worksheet-tools select{width:100%;border:1px solid #cfd9e4;background:#fff;border-radius:11px;padding:10px 11px}.transform-groups{display:grid;gap:8px}.transform-btn{border:1px solid var(--line);background:#fff;border-radius:12px;padding:10px;text-align:left}.transform-btn.active{background:#eef7ff;border-color:#9bcaee}.parameter-box{border:1px solid var(--line);border-radius:13px;background:#f8fafc;padding:10px;margin-top:8px}.parameter-box input{width:100%}.graph-panel{overflow:hidden}.graph-panel canvas{width:100%;height:auto;display:block}.lab-detail-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;margin-top:14px}.detail-card{background:#fff;border:1px solid var(--line);border-radius:18px;padding:15px}.detail-card h4{margin:0 0 7px;font-size:.96rem}.detail-card p,.detail-card li{font-size:.89rem;color:#53647a}.detail-card ol{padding-left:1.2rem}
.practice-wrap{display:grid;grid-template-columns:240px 1fr;gap:18px}.practice-menu{display:grid;gap:8px;align-self:start}.practice-menu button{border:1px solid var(--line);background:#fff;border-radius:13px;padding:11px;text-align:left;font-weight:820;color:#4a5a70}.practice-menu button.active{background:#0c1726;color:#fff;border-color:#0c1726}.practice-card{background:#fff;border:1px solid var(--line);border-radius:22px;padding:24px;box-shadow:var(--shadow);min-height:350px}.practice-question{font-size:1.08rem;font-weight:780}.practice-options{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:9px;margin:16px 0}.practice-options button{border:1px solid var(--line);background:#fff;border-radius:13px;padding:12px;text-align:left}.practice-options button:hover{background:#f8fafc}.practice-options button.correct{background:#eafbf7;border-color:#7ed6c8}.practice-options button.wrong{background:#fff0f4;border-color:#eca6b7}.feedback{border:1px solid var(--line);background:#f8fafc;border-radius:14px;padding:12px;margin:12px 0}.practice-footer{display:flex;justify-content:space-between;gap:10px;align-items:center}.score{font-size:.88rem;color:#65758a;font-weight:800}
.worksheet-tools{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:11px;background:#fff;border:1px solid var(--line);border-radius:20px;padding:15px}.worksheet-tools label{font-size:.82rem;font-weight:850;color:#4f6075}.worksheet-tools select{margin-top:5px}.topic-picker{display:flex;gap:8px;flex-wrap:wrap;margin:13px 0}.topic-check{display:flex;align-items:center;gap:6px;background:#fff;border:1px solid var(--line);border-radius:999px;padding:7px 10px;font-size:.84rem;font-weight:760;color:#4c5d73}.worksheet-actions{display:flex;gap:8px;flex-wrap:wrap;margin:12px 0}.worksheet-note{background:#f8fafc;border:1px solid var(--line);border-radius:14px;padding:12px 14px;color:#58687e;font-size:.87rem}.worksheet-preview{background:#fff;border:1px solid var(--line);border-radius:22px;padding:24px;box-shadow:var(--shadow);margin-top:15px}.ws-head{text-align:center;border-bottom:2px solid #132034;padding-bottom:12px;margin-bottom:18px}.ws-head h3{margin:0;font-size:1.45rem}.ws-head p{margin:.25rem 0;color:#65758a}.ws-item{break-inside:avoid;margin-bottom:18px}.ws-prompt{color:#27364b}.workbox{height:150px;border:1px solid #cbd7e3;border-radius:10px;margin-top:10px;background-image:linear-gradient(#e3e9f0 1px,transparent 1px),linear-gradient(90deg,#e3e9f0 1px,transparent 1px);background-size:21px 21px}.workbox.large{height:230px}.solution{margin-top:9px;background:#eafbf7;border-left:4px solid #159e8b;border-radius:0 12px 12px 0;padding:12px 14px}.solution strong{display:block;margin-bottom:4px}.solution ol{margin:.35rem 0;padding-left:1.2rem}.hidden-solutions .solution{display:none}
.site-footer{background:#07131f;color:#c9d8e7;border-top:1px solid rgba(255,255,255,.07);padding:28px 20px;text-align:center;font-size:.86rem}.site-footer p{max-width:980px;margin:.35rem auto}
@media(max-width:1020px){.hero-inner,.chapter-grid,.special-lab-grid,.lab-layout,.practice-wrap{grid-template-columns:1fr}.learning-map{grid-template-columns:repeat(2,minmax(0,1fr))}.hero-board{max-width:760px}.quick-consequences{grid-template-columns:1fr 1fr}.lab-detail-grid{grid-template-columns:1fr}.worksheet-tools{grid-template-columns:repeat(2,minmax(0,1fr))}.practice-menu{grid-template-columns:repeat(3,minmax(0,1fr))}.practice-menu button{text-align:center}}
@media(max-width:680px){.hero-inner{padding:40px 15px 34px}.hero-board{display:none}.app-shell{padding:24px 11px 56px}.section-top{display:block}.section-top>p{margin-top:10px}.learning-map,.callout-grid,.split-note,.quick-consequences,.practice-options,.base-grid{grid-template-columns:1fr}.special-hero{padding:22px 17px;border-radius:23px}.theory-point{grid-template-columns:45px 1fr;padding:13px}.point-num{width:38px;height:38px}.ordinate-map{grid-template-columns:1fr}.map-arrow{transform:rotate(90deg);text-align:center}.ordinate-slider,.ordinate-note{grid-column:1}.worksheet-tools{grid-template-columns:1fr}.worksheet-preview{padding:15px}.practice-menu{grid-template-columns:1fr 1fr}.chapter-card{padding:18px 15px}.main-nav{padding-left:7px}.formula-table{font-size:.9rem}}
@media print{body{background:white}.hero-shell,.main-nav,.section-top,.worksheet-tools,.topic-picker,.worksheet-actions,.worksheet-note,.site-footer,.screen:not(#worksheets){display:none!important}.app-shell{max-width:none;padding:0}#worksheets{display:block!important}.worksheet-preview{box-shadow:none;border:0;border-radius:0;padding:0}.workbox{height:120px}.workbox.large{height:185px}.ws-item{page-break-inside:avoid}.solution{break-inside:avoid}}

/* Worksheet level prompts */
.level-extra{display:inline-block;margin-top:.45rem;padding:.45rem .65rem;border-radius:.65rem;background:#eef8f6;color:#173d3a;font-size:.94em}

/* v4 illustrated theory */
.graph-example-grid{display:grid;gap:16px;margin:18px 0}.graph-example-grid.two{grid-template-columns:repeat(2,minmax(0,1fr))}.graph-example-grid.three{grid-template-columns:repeat(3,minmax(0,1fr))}.graph-example-grid.four{grid-template-columns:repeat(2,minmax(0,1fr))}.graph-example{background:#fff;border:1px solid var(--line);border-radius:22px;overflow:hidden;box-shadow:var(--shadow2)}.graph-example-head{display:flex;justify-content:space-between;gap:12px;align-items:start;padding:15px 16px 10px}.graph-example-head h4{margin:0;font-size:1rem}.graph-example-kicker{display:block;color:var(--teal);font-weight:900;text-transform:uppercase;letter-spacing:.09em;font-size:.67rem;margin-bottom:4px}.formula-pair{display:flex;align-items:center;gap:7px;flex-wrap:wrap;justify-content:flex-end;font-size:.84rem}.formula-pair>span:not(.pair-arrow){background:#f7f9fc;border:1px solid var(--line);padding:5px 8px;border-radius:9px}.pair-arrow{color:var(--violet);font-weight:950}.graph-example canvas{width:100%;height:auto;display:block;border-top:1px solid var(--line);border-bottom:1px solid var(--line);background:#fff}.graph-legend.compact{padding:8px 14px;font-size:.76rem}.graph-example-note{padding:0 15px 15px;margin:0;color:#52647a;font-size:.88rem}.square-compare{display:grid;grid-template-columns:minmax(0,1fr) minmax(390px,.9fr);gap:22px;align-items:start;background:linear-gradient(135deg,#fff,#f8fbff)}.square-compare-copy h3{font-size:1.65rem}.position-rules{display:grid;gap:9px;margin:16px 0}.position-rule{display:grid;grid-template-columns:140px 1fr;gap:10px;align-items:center;border-radius:14px;padding:11px 12px;border:1px solid var(--line)}.position-rule strong{display:flex;align-items:center}.position-rule.up{background:#eafbf7;border-color:#a9eadf}.position-rule.down{background:#fff3ec;border-color:#ffd1bd}.position-rule.same{background:#f3f1ff;border-color:#d5d1ff}.micro-note{background:#f8fafc;border:1px solid var(--line);padding:12px 14px;border-radius:14px}.square-compare-graph{background:white;border:1px solid var(--line);border-radius:18px;overflow:hidden}.square-compare-graph canvas{width:100%;height:auto;display:block;border-top:1px solid var(--line)}
@media(max-width:1020px){.graph-example-grid.three{grid-template-columns:1fr 1fr}.square-compare{grid-template-columns:1fr}}
@media(max-width:680px){.graph-example-grid.two,.graph-example-grid.three,.graph-example-grid.four{grid-template-columns:1fr}.graph-example-head{display:block}.formula-pair{justify-content:flex-start;margin-top:8px}.position-rule{grid-template-columns:1fr}}
.workbox{position:relative;overflow:hidden}.workbox::before,.workbox::after{content:"";position:absolute;background:#8b98a9;opacity:.62;pointer-events:none}.workbox::before{width:1.5px;top:0;bottom:0;left:50%}.workbox::after{height:1.5px;left:0;right:0;top:50%}

/* v5 — PDF compilato da LaTeX e grafici nel correttore */
.btn-pdf{background:linear-gradient(135deg,#132034,#314764);color:#fff;border:1px solid #132034;box-shadow:0 8px 22px rgba(19,32,52,.14)}
.btn-pdf:hover{box-shadow:0 11px 28px rgba(19,32,52,.2)}
.compile-status{background:#eef7ff;border:1px solid #c6ddf2;border-left:4px solid #4d8fc5;border-radius:0 14px 14px 0;padding:12px 14px;color:#40546d;font-size:.87rem;margin:12px 0}.compile-status.working{background:#fff8e9;border-color:#f3cf7b;border-left-color:#d59b19}.compile-status.error{background:#fff0f4;border-color:#efb2c0;border-left-color:#d84a63}.compile-status code{font-size:.84em}
.solution-graph{margin-top:12px;background:#fff;border:1px solid #cfe0dc;border-radius:15px;overflow:hidden}.solution-graph canvas{display:block;width:100%;height:auto;background:#fff}.solution-legend{display:flex;gap:15px;align-items:center;flex-wrap:wrap;padding:9px 12px;border-top:1px solid #dbe7e4;background:#f8fcfb;font-size:.8rem;color:#52647a}.legend-asymptote{height:0;border-top:3px dashed #d84a63;background:transparent;border-radius:0}
@media(max-width:680px){.solution-legend{gap:9px}.worksheet-actions .btn{width:100%}}
@media print{.compile-status{display:none!important}.solution-graph{break-inside:avoid}}