:root{color-scheme:dark;--night: #0b2230;--ink: #07171f;--paper: #f4ecd8;--paper-bright: #fff8e7;--paper-ink: #17252b;--muted-night: #b7c7c8;--muted-paper: #526268;--brass: #e7b84c;--brass-dark: #755814;--coral: #f06f51;--coral-dark: #c84931;--aqua: #5fc2b4;--lilac: #a89ad7;--danger: #b83d3d;--sans: "Avenir Next", "Segoe UI", Helvetica, Arial, sans-serif;--serif: Georgia, "Times New Roman", serif;--shadow: 10px 10px 0 var(--ink)}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:88px;background:var(--night)}body{margin:0;min-width:320px;background:var(--night);color:var(--paper-bright);font:16px/1.55 var(--sans)}button,input,textarea{font:inherit}button,a{-webkit-tap-highlight-color:transparent}a{color:inherit;text-underline-offset:.22em}img{display:block;max-width:100%}[hidden]{display:none!important}:focus-visible{outline:3px solid var(--brass);outline-offset:4px}::selection{background:var(--brass);color:var(--ink)}.sr-only{position:absolute!important;width:1px!important;height:1px!important;padding:0!important;margin:-1px!important;overflow:hidden!important;clip:rect(0,0,0,0)!important;white-space:nowrap!important;border:0!important}.skip-link{position:fixed;z-index:100;left:16px;top:12px;padding:12px 18px;background:var(--brass);color:var(--ink);font-weight:800;transform:translateY(-160%)}.skip-link:focus{transform:translateY(0)}.offline-bar{position:sticky;z-index:50;top:0;padding:8px 16px;background:var(--brass);color:var(--ink);text-align:center;font-weight:750}.site-header{position:relative;z-index:10;display:flex;align-items:center;justify-content:space-between;max-width:1240px;min-height:88px;margin:0 auto;padding:16px 32px;border-bottom:1px solid #47606a}.brand{display:inline-flex;align-items:center;gap:10px;color:var(--paper-bright);font:700 16px/1.05 var(--serif);letter-spacing:.08em;text-decoration:none;text-transform:uppercase}.brand small{color:var(--brass);font:700 11px/1 var(--sans);letter-spacing:.25em}.brand-mark{display:grid;width:44px;height:44px;place-items:center;border:2px solid var(--brass);border-radius:50%;color:var(--coral);font:26px/1 var(--serif)}.site-header nav,footer nav{display:flex;gap:28px}.site-header nav a,footer nav a{color:var(--muted-night);font-size:14px;font-weight:700;letter-spacing:.04em}.site-header nav a:hover,footer nav a:hover{color:var(--paper-bright)}main{overflow:hidden}.hero{display:grid;grid-template-columns:minmax(0,1.1fr) minmax(320px,.62fr);align-items:center;gap:clamp(40px,7vw,100px);width:min(1180px,calc(100% - 64px));min-height:700px;margin:0 auto;padding:64px 0 90px}.hero-copy{position:relative;z-index:1}.hero-copy:before{content:"";position:absolute;z-index:-1;top:-48px;left:-58px;width:110px;height:110px;border:1px solid #41606b;border-radius:50%;box-shadow:inset 0 0 0 13px var(--night),inset 0 0 0 14px #41606b}.eyebrow{margin:0 0 12px;color:var(--brass-dark);font-size:12px;font-weight:850;letter-spacing:.18em;text-transform:uppercase}.hero .eyebrow,.inverse .eyebrow,.drill-work>.eyebrow{color:var(--brass)}.eyebrow span{display:inline-block;padding-bottom:4px;border-bottom:2px solid var(--coral)}h1,h2,h3,h4,p{margin-top:0}h1,h2,h3{font-family:var(--serif)}h1{max-width:820px;margin-bottom:28px;color:var(--paper-bright);font-size:clamp(2.65rem,6vw,5.6rem);font-weight:600;line-height:.98;letter-spacing:-.045em;text-wrap:balance}h2{margin-bottom:16px;color:var(--paper-ink);font-size:clamp(2rem,4vw,3.4rem);font-weight:600;line-height:1.05;letter-spacing:-.035em}h3{margin-bottom:18px;color:var(--paper-ink);font-size:clamp(1.8rem,4vw,3rem);line-height:1.06}h4{margin-bottom:20px;color:var(--paper-ink);font-size:1.2rem;line-height:1.35}.hero-lead{max-width:650px;margin-bottom:32px;color:var(--muted-night);font-size:clamp(1.08rem,2vw,1.25rem);line-height:1.65}.hero-lead strong{color:var(--paper-bright);font-weight:700}.hero-actions{display:flex;flex-wrap:wrap;gap:12px;margin-bottom:24px}.button{display:inline-flex;min-height:48px;align-items:center;justify-content:center;padding:12px 20px;border:2px solid currentColor;border-radius:1px;background:transparent;color:inherit;font-weight:800;letter-spacing:.02em;text-decoration:none;cursor:pointer;transition:transform .18s ease,box-shadow .18s ease,background .18s ease}.button:hover{transform:translate(-2px,-2px);box-shadow:5px 5px 0 var(--ink)}.button:active{transform:translate(1px,1px);box-shadow:none}.button.primary{border-color:var(--brass);background:var(--brass);color:var(--ink)}.button.secondary{border-color:var(--night);color:var(--night)}.button.ghost{border-color:#779096;color:var(--paper-bright)}.button.compact{min-height:44px;padding:8px 18px}.local-note{color:var(--muted-night);font-size:14px}.local-note span{margin-right:8px;color:var(--aqua)}.poster-frame{position:relative;margin:0;padding:10px;border:1px solid var(--brass);background:var(--ink);box-shadow:16px 16px #041015;animation:poster-arrive .36s ease-out both}.poster-frame:after{content:"";position:absolute;inset:16px;border:1px solid rgba(231,184,76,.58);pointer-events:none}.poster-frame img{width:100%;height:auto;aspect-ratio:2/3;object-fit:cover}.poster-frame figcaption{position:absolute;right:-12px;bottom:28px;width:180px;padding:10px 14px;background:var(--paper);color:var(--paper-ink);font-size:12px;font-weight:700;box-shadow:6px 6px 0 var(--ink)}.method{display:grid;grid-template-columns:.8fr 1.4fr;gap:60px;padding:80px max(32px,calc((100vw - 1180px)/2));background:var(--brass);color:var(--paper-ink)}.method h2{max-width:500px;margin-bottom:0}.method .eyebrow,.scratch-copy .eyebrow{color:#4f3b0b}.method-line{position:relative;display:grid;grid-template-columns:repeat(3,1fr);gap:32px;margin:10px 0 0;padding:0;list-style:none}.method-line:before{content:"";position:absolute;top:22px;left:20px;right:20px;height:4px;background:var(--night)}.method-line li{position:relative;display:grid;grid-template-columns:46px 1fr;align-items:center;column-gap:10px}.method-line span{z-index:1;display:grid;width:46px;height:46px;place-items:center;border:4px solid var(--night);border-radius:50%;background:var(--brass);font-weight:900}.method-line strong,.method-line small{grid-column:2}.method-line small{color:#4a3c19;line-height:1.4}.notice{width:min(1180px,calc(100% - 64px));margin:32px auto;padding:16px 20px;border-left:6px solid var(--brass);background:var(--paper);color:var(--paper-ink)}.notice p{margin-bottom:0}.practice,.transfer{padding:96px max(32px,calc((100vw - 1180px)/2));background:var(--paper);color:var(--paper-ink)}.section-heading{display:flex;align-items:end;justify-content:space-between;gap:32px;margin-bottom:44px}.section-heading>div:first-child{max-width:720px}.section-heading h2{margin-bottom:8px}.section-heading p{margin-bottom:0;color:var(--muted-paper)}.progress-summary{min-width:220px;color:var(--muted-paper);text-align:right}.progress-summary strong{color:var(--paper-ink);font-size:1.5rem}.progress-track{width:220px;height:8px;margin-top:8px;border:1px solid var(--night);background:#ded4bf}.progress-track i{display:block;height:100%;background:var(--coral-dark);transition:width .24s ease}.workbench{display:grid;grid-template-columns:minmax(240px,320px) minmax(0,1fr);align-items:start;gap:clamp(28px,6vw,76px)}.route-map{position:relative;max-height:680px;overflow:auto;padding:4px 12px 24px 4px;scrollbar-color:var(--coral-dark) #ded4bf}.route-map:before{content:"";position:absolute;z-index:0;top:48px;bottom:30px;left:26px;width:5px;background:var(--coral-dark);box-shadow:9px 0 0 var(--aqua),18px 0 0 var(--lilac),27px 0 0 var(--brass)}.zone-label{position:relative;z-index:1;margin:24px 0 8px;padding:3px 8px;background:var(--paper);color:var(--muted-paper);font-size:11px;font-weight:850;letter-spacing:.14em;text-transform:uppercase}.zone-label:first-child{margin-top:0}.station{position:relative;z-index:1;display:grid;grid-template-columns:44px 8px 1fr 24px;width:100%;min-height:54px;align-items:center;gap:8px;padding:5px 4px;border:0;background:transparent;color:var(--paper-ink);text-align:left;cursor:pointer}.station>span{display:grid;width:40px;height:40px;place-items:center;border:2px solid var(--night);border-radius:50%;background:var(--paper);font-size:12px;font-weight:900;font-variant-numeric:tabular-nums}.station>i{width:8px;height:8px;border-radius:50%;background:var(--coral-dark)}.station>i.line-estimate{background:var(--brass-dark)}.station>i.line-table{background:#287f73}.station>i.line-algebra{background:#6d5fa3}.station em{font-style:normal;font-weight:650;line-height:1.25}.station b{font-size:16px;text-align:center}.station.active{background:var(--night);color:var(--paper-bright)}.station.active>span{border-color:var(--brass);background:var(--night);color:var(--paper-bright)}.station.done:not(.active)>span{background:var(--aqua)}.drill-panel{min-width:0;padding:clamp(24px,5vw,56px);border:2px solid var(--night);background:#fffaf0;box-shadow:var(--shadow)}.drill-head{display:flex;justify-content:space-between;gap:16px}.station-number{color:var(--coral-dark);font-size:12px;font-weight:850;letter-spacing:.14em;text-transform:uppercase}.complete-stamp{align-self:start;padding:3px 8px;border:2px solid #176a5e;color:#176a5e;font-size:12px;font-weight:850;text-transform:uppercase;transform:rotate(-2deg)}.drill-prompt{max-width:690px;margin-bottom:36px;color:#34474e;font-size:1.12rem}fieldset{min-width:0;margin:0;padding:0;border:0}legend{padding:0;color:var(--paper-ink);font-weight:800}.tool-choice>p{margin:4px 0 16px;color:var(--muted-paper);font-size:14px}.tool-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:10px}.tool-button{display:grid;grid-template-columns:40px 1fr;min-height:88px;align-items:center;gap:2px 10px;padding:12px;border:1px solid #9a947f;background:transparent;color:var(--paper-ink);text-align:left;cursor:pointer;transition:transform .16s ease,border-color .16s ease,background .16s ease}.tool-button:hover{border-color:var(--night);transform:translateY(-2px)}.tool-button.selected{border:3px solid var(--coral-dark);background:#fff2e7}.tool-button>span{grid-row:span 2;display:grid;width:40px;height:40px;place-items:center;border:2px solid currentColor;border-radius:50%;font:700 22px/1 var(--serif)}.tool-button strong{align-self:end}.tool-button small{align-self:start;color:var(--muted-paper);font-size:12px;line-height:1.25}.tool-feedback{min-height:0;margin-top:16px;padding:0;color:var(--muted-paper)}.tool-feedback:not(:empty){padding:12px 16px;border-left:5px solid var(--danger);background:#f6dfd5}.tool-feedback.success{border-color:#176a5e;background:#dcece4;color:var(--paper-ink)}.drill-work{margin:32px -16px -16px;padding:32px 16px 16px;border-top:5px double var(--night)}.drill-work>.eyebrow{color:var(--coral-dark)}.estimate-ticket,.algebra-strip{display:flex;flex-wrap:wrap;min-height:70px;align-items:center;justify-content:space-between;gap:16px;margin-bottom:24px;padding:16px 20px;border:2px solid var(--brass-dark);background:#fff2c9}.estimate-ticket>span,.algebra-strip>span{font-size:11px;font-weight:850;letter-spacing:.12em;text-transform:uppercase}.estimate-ticket>strong{flex-basis:100%;padding-top:12px;border-top:1px solid var(--brass-dark);font-size:1.3rem}.algebra-strip code{color:var(--paper-ink);font:700 1.15rem/1.4 var(--serif)}.text-button{min-height:44px;padding:6px 8px;border:0;background:transparent;color:#215e80;font-weight:800;text-decoration:underline;text-underline-offset:4px;cursor:pointer}.text-button.danger{color:#9f2929}.table-scroll{max-width:100%;margin-bottom:24px;overflow-x:auto}table{width:100%;border-collapse:collapse;background:var(--paper-bright);color:var(--paper-ink);font-variant-numeric:tabular-nums}caption{padding:8px;color:var(--muted-paper);font-weight:700;text-align:left}th,td{padding:10px 14px;border-bottom:1px solid #c7bda8;text-align:right}thead th{background:var(--night);color:var(--paper-bright)}tbody th{font-weight:700}.mini-plot-wrap{display:grid;grid-template-columns:minmax(0,1.6fr) minmax(190px,.7fr);gap:16px;align-items:start;margin-bottom:24px}.plot-canvas{display:block;width:100%;height:400px;border:2px solid var(--night);background:#fffaf0}.mini-plot{height:300px}.answer-form{margin-top:24px}.answer-form legend{margin-bottom:12px}.answer-option{display:flex;min-height:48px;align-items:center;gap:12px;margin:8px 0;padding:9px 12px;border:1px solid #aaa08a;cursor:pointer}.answer-option:has(input:checked){border:2px solid var(--coral-dark);background:#fff2e7}.answer-option input{width:20px;height:20px;accent-color:var(--coral-dark)}.answer-form .button{margin-top:12px}.answer-feedback{display:inline;margin-left:12px;color:#982e2e;font-weight:700}.answer-feedback.success{color:#176a5e}.explanation{margin:24px 0;padding:18px 20px;border-left:5px solid #176a5e;background:#dcece4}.explanation p{margin:4px 0 0}.plotter-section{padding:96px max(32px,calc((100vw - 1180px)/2));background:var(--night);color:var(--paper-bright)}.section-heading.inverse h2{color:var(--paper-bright)}.section-heading.inverse p{color:var(--muted-night)}.route-badge{display:inline-flex;min-height:44px;align-items:center;padding:8px 16px;border:2px solid var(--night);border-radius:50%;color:var(--paper-ink);font-size:13px;font-weight:850;white-space:nowrap}.route-badge.graph{border-color:var(--coral);color:var(--paper-bright)}.plot-controls{display:grid;grid-template-columns:minmax(240px,1fr) auto auto;align-items:end;gap:16px;margin-bottom:20px}.expression-field,.range-fields label{display:grid;gap:6px;color:var(--muted-night);font-size:12px;font-weight:800;letter-spacing:.05em;text-transform:uppercase}.expression-field{position:relative}.expression-field input{width:100%;height:50px;padding:8px 14px 8px 58px;border:2px solid #779096;background:var(--ink);color:var(--paper-bright);font:1.15rem var(--serif)}.math-prefix{position:absolute;bottom:11px;left:14px;color:var(--brass);font:1.1rem var(--serif)}.range-fields{display:grid;grid-template-columns:repeat(4,72px);gap:8px}.range-fields input{width:72px;height:50px;padding:6px;border:2px solid #779096;background:var(--ink);color:var(--paper-bright);font-variant-numeric:tabular-nums}.field-help{grid-column:1 / -1;margin:-8px 0 0;color:var(--muted-night);font-size:13px}code{padding:2px 5px;background:#ffffff14}.plot-error,.inline-error{min-height:24px;color:#ffb8a8;font-weight:750}.plot-grid{display:grid;grid-template-columns:minmax(0,1.65fr) minmax(220px,.6fr);gap:24px;align-items:start}.plot-table table{background:var(--paper)}.transfer{background:#e9dfca}.quiz-list{display:grid;gap:16px}.quiz-question{padding:24px;border:1px solid #8f8877;background:var(--paper)}.quiz-question legend{display:grid;grid-template-columns:38px 1fr;align-items:center;gap:12px;width:100%;font-size:1.06rem}.quiz-question legend>span{display:grid;width:36px;height:36px;place-items:center;border:2px solid var(--night);border-radius:50%}.quiz-tools{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin-top:18px}.quiz-tools label{position:relative}.quiz-tools input{position:absolute;opacity:0}.quiz-tools span{display:flex;min-height:46px;align-items:center;justify-content:center;padding:8px;border:1px solid #918877;font-weight:700;cursor:pointer}.quiz-tools input:focus-visible+span{outline:3px solid var(--coral-dark);outline-offset:2px}.quiz-tools input:checked+span{border:3px solid var(--coral-dark);background:#fff2e7}.quiz-question.correct{border:3px solid #176a5e}.quiz-question.incorrect{border:3px solid var(--danger)}.quiz-result{margin:14px 0 0 50px;color:var(--muted-paper)}.quiz-result strong{color:var(--paper-ink)}.quiz-actions{display:flex;align-items:center;gap:16px;margin-top:16px}.quiz-actions .inline-error{color:#982e2e}.score-seal{display:grid;width:122px;height:122px;place-items:center;align-content:center;border:3px double var(--coral-dark);border-radius:50%;color:var(--coral-dark);text-align:center;transform:rotate(2deg)}.score-seal strong{font:700 2rem/1 var(--serif)}.score-seal span{font-size:11px;font-weight:850;text-transform:uppercase}.scratch-section{display:grid;grid-template-columns:.7fr 1.3fr;gap:clamp(40px,8vw,110px);padding:96px max(32px,calc((100vw - 1000px)/2));background:var(--brass);color:var(--paper-ink)}.scratch-copy h2{margin-bottom:16px}.scratch-paper{padding:24px 26px 18px 54px;background-color:#fffaf0;background-image:linear-gradient(#cdd8d8 1px,transparent 1px);background-size:100% 31px;box-shadow:12px 12px #8b671b}.scratch-paper label{display:block;margin-bottom:8px;font-size:12px;font-weight:850;letter-spacing:.12em;text-transform:uppercase}.scratch-paper textarea{width:100%;min-height:260px;resize:vertical;border:0;background:transparent;color:var(--paper-ink);line-height:31px;outline-offset:3px}.scratch-paper textarea::placeholder{color:#6e797d}.scratch-actions{display:flex;flex-wrap:wrap;align-items:center;justify-content:flex-end;gap:4px 10px}.scratch-actions>span{margin-right:auto;color:var(--muted-paper);font-size:12px}.reset-zone{display:flex;align-items:center;justify-content:space-between;gap:28px;padding:48px max(32px,calc((100vw - 1000px)/2));border-top:1px solid #45616c;color:var(--muted-night)}.reset-zone h2{margin-bottom:4px;color:var(--paper-bright);font:600 1.35rem var(--serif)}.reset-zone p{margin-bottom:0}footer{display:flex;align-items:end;justify-content:space-between;gap:40px;max-width:1180px;margin:0 auto;padding:60px 32px calc(60px + env(safe-area-inset-bottom));border-top:1px solid #47606a;color:var(--muted-night);font-size:13px}.footer-brand{margin-bottom:16px}footer>div:last-child{text-align:right}footer nav{justify-content:flex-end}.noscript{max-width:700px;margin:80px auto;padding:32px}@keyframes poster-arrive{0%{opacity:0;transform:translateY(18px) rotate(.8deg)}to{opacity:1;transform:none}}@media(max-width:900px){.hero{grid-template-columns:1fr .55fr;width:min(100% - 40px,900px);gap:32px}.hero h1{font-size:clamp(2.7rem,7vw,4.5rem)}.method{grid-template-columns:1fr;gap:32px}.workbench{grid-template-columns:1fr}.route-map{display:flex;max-width:100%;max-height:none;gap:8px;overflow-x:auto;padding-bottom:12px}.route-map:before,.route-map .zone-label,.station>i{display:none}.station em{position:absolute;width:1px;height:1px;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap}.station{display:grid;flex:0 0 52px;grid-template-columns:1fr;width:52px;min-height:52px;padding:4px}.station>span{margin:auto}.station b{position:absolute;right:0;bottom:0}.plot-controls{grid-template-columns:1fr auto}.range-fields{grid-row:2;grid-column:1 / -1}.field-help{grid-row:3}.mini-plot-wrap{grid-template-columns:1fr}}@media(max-width:700px){.site-header{min-height:72px;padding:12px 20px}.site-header nav{gap:14px}.site-header nav a{font-size:12px}.brand{font-size:13px}.brand-mark{width:38px;height:38px}.hero{grid-template-columns:1fr;width:calc(100% - 40px);min-height:0;padding:54px 0 70px}.hero-copy:before{left:-22px}.poster-frame{width:min(360px,88%);margin:10px auto 0}.method,.practice,.plotter-section,.transfer,.scratch-section{padding:68px 20px}.method-line{grid-template-columns:1fr;gap:18px}.method-line:before{top:20px;bottom:20px;left:21px;width:4px;height:auto}.section-heading{display:grid;align-items:start}.progress-summary{min-width:0;text-align:left}.progress-track{width:100%}.drill-panel{padding:24px 18px;box-shadow:7px 7px 0 var(--ink)}.tool-grid,.plot-controls{grid-template-columns:1fr}.range-fields{grid-template-columns:repeat(4,1fr);grid-row:auto;grid-column:auto}.range-fields input{width:100%}.field-help{grid-row:auto}.plot-grid{grid-template-columns:1fr}.plot-canvas{height:300px}.quiz-tools{grid-template-columns:repeat(2,1fr)}.quiz-question{padding:18px 14px}.quiz-question legend{grid-template-columns:36px 1fr}.quiz-result{margin-left:0}.scratch-section{grid-template-columns:1fr}.scratch-paper{padding-left:30px}.reset-zone,footer{align-items:stretch;flex-direction:column;padding-right:20px;padding-left:20px}footer>div:last-child{text-align:left}footer nav{justify-content:flex-start}}@media(max-width:430px){.site-header nav a:nth-child(2){display:none}.hero h1{font-size:2.75rem}.hero-actions{display:grid}.hero-actions .button{width:100%}.drill-head{display:grid}.complete-stamp{justify-self:start}.range-fields{grid-template-columns:repeat(2,1fr)}.answer-feedback{display:block;margin:10px 0 0}.scratch-actions{align-items:start;flex-direction:column}.scratch-actions>span{margin-bottom:4px}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}}@media print{.site-header,.hero,.method,.route-map,.plotter-section,.transfer,.reset-zone,footer,.button{display:none!important}body,.practice,.scratch-section{background:#fff;color:#000}.practice,.scratch-section{padding:24px}.workbench,.scratch-section{display:block}.drill-panel,.scratch-paper{border:1px solid black;box-shadow:none}}