:root{color-scheme:light;--bg:#f0f4f7;--paper:#f9fbfd;--ink:#192c3c;--muted:#4e6578;--line:#bccbd5;--soft:#e3ebf1;--shadow:none;--sans:'Avenir Next',Avenir,'Segoe UI',sans-serif;--serif:Georgia,'Times New Roman',serif;--mono:'SFMono-Regular',Consolas,'Liberation Mono',monospace;--accent:#83501c;--accent-soft:#f6e9d7;--ok:#23664a;--bad:#983f38}html[data-theme=dark]{color-scheme:dark;--bg:#090f16;--paper:#101a25;--ink:#e0e7ee;--muted:#98a7b7;--line:#253340;--soft:#192b3b;--shadow:none;--accent:#ebbd80;--accent-soft:#302a23;--ok:#8bd3ad;--bad:#f4a49b}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font:15px/1.65 var(--sans)}button,input,select,textarea{font:inherit}button,a,input,textarea,summary{outline-offset:4px}button:focus-visible,a:focus-visible,input:focus-visible,textarea:focus-visible,select:focus-visible,summary:focus-visible{outline:2px solid var(--accent)}button,a{-webkit-tap-highlight-color:transparent}button{cursor:pointer;color:inherit;border:1px solid var(--line);background:transparent;border-radius:6px;padding:9px 13px;font-size:13px;line-height:1.5}button:hover{border-color:var(--accent);background:var(--soft)}button:disabled{opacity:.5;cursor:default}a{color:inherit;text-underline-offset:4px}h1,h2,h3,p{margin-top:0}button.primary{background:var(--ink);color:var(--paper);border-color:var(--ink);font-weight:600;display:inline-flex;align-items:center;justify-content:space-between;gap:24px}button.primary:hover{filter:brightness(.9)}.top,main,footer{max-width:1400px;margin:auto;padding-left:48px;padding-right:48px}.top{height:100px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line)}.brand{display:flex;align-items:center;gap:10px;text-decoration:none;font-size:24px;font-weight:600;letter-spacing:-1px}.brand-mark{font:bold 28px Georgia;background:var(--ink);color:var(--paper);border-radius:10px;width:40px;height:40px;text-align:center;letter-spacing:-4px;padding-right:4px}.brand-mark span{color:#dfb47d}.edition{font:9px var(--mono);letter-spacing:1px;margin:8px 0 0 10px;color:var(--muted)}.top-actions{display:flex;align-items:center;gap:10px;font-size:12px}.top-actions a{padding-left:10px;text-decoration:none}.intro{display:grid;grid-template-columns:1fr 300px;gap:50px;align-items:center;padding:60px 0 54px}.eyebrow,.label{font:10px var(--mono);letter-spacing:1.8px;color:var(--muted)}.eyebrow{margin-bottom:18px}h1{font:clamp(42px,5.2vw,72px)/1.02 Georgia,serif;letter-spacing:-2px;margin-bottom:22px}h1 em{color:var(--accent);font-weight:400}.lede{color:var(--muted);font-size:16px;margin:0}.session-card{padding:25px;border:1px solid var(--line);border-radius:10px;background:var(--paper);box-shadow:var(--shadow)}.session-card p{font:28px/1.25 Georgia;margin:18px 0}.session-card .primary{width:100%;font-size:13px}.session-card small{display:block;color:var(--muted);font-size:10px;margin-top:14px}.workbench{display:grid;grid-template-columns:290px minmax(0,1fr);border:1px solid var(--line);border-radius:10px;overflow:hidden;background:var(--paper);box-shadow:var(--shadow)}.library{min-width:0;padding:24px 18px;background:var(--soft);border-right:1px solid var(--line)}.library-head{display:flex;align-items:center;justify-content:space-between;margin-bottom:16px}.library-head h2{font-size:15px;margin:0}.library-head>span{font:11px var(--mono);color:var(--muted)}.search input{width:100%;border:1px solid var(--line);border-radius:6px;background:var(--paper);color:var(--ink);padding:10px;font-size:11px}#tracks{display:flex;flex-direction:column;gap:3px;margin:17px 0}#tracks button{font-size:12px;text-align:left;background:transparent;border-color:transparent;padding:7px 10px}#tracks button[aria-pressed=true]{background:var(--paper);border-color:var(--line);font-weight:600}.queue{width:100%;display:flex;justify-content:space-between;font-size:12px;background:transparent}.queue[aria-pressed=true]{border-color:var(--accent);color:var(--accent)}.library-caption{display:flex;justify-content:space-between;font:9px var(--mono);color:var(--muted);margin:25px 0 12px}#exercise-list{display:flex;flex-direction:column;gap:8px;max-height:780px;overflow:auto;padding:3px}.exercise-card{text-align:left;display:flex;flex-direction:column;gap:5px;padding:14px;background:transparent;border-color:transparent;border-left:3px solid transparent;border-radius:3px}.exercise-card[aria-current=true]{background:var(--paper);border-left-color:var(--accent);box-shadow:0 3px 12px #00000005}.card-tag{font:9px var(--mono);color:var(--muted)}.exercise-card strong{font-size:13px;line-height:1.4}.card-concept{font-size:10px;color:var(--muted)}.library-foot{font-size:10px;color:var(--muted);margin:25px 0 0}.empty{font-size:12px;color:var(--muted);padding:12px}.workspace{padding:30px 36px;min-width:0;scroll-margin-top:20px}.workspace:focus{outline:none}.exercise-top{display:flex;align-items:center;justify-content:space-between;gap:15px;margin-bottom:30px}.exercise-top button{font-size:11px;border:0;background:var(--soft)}.exercise-top button[aria-pressed=true]{color:var(--accent)}.exercise-heading{display:flex;gap:17px;align-items:flex-start}.exercise-number{font:24px Georgia;color:var(--accent);padding-top:4px}.exercise-heading h2{font:32px/1.17 Georgia;margin-bottom:12px;letter-spacing:-.5px}.exercise-meta{display:flex;flex-wrap:wrap;gap:12px;color:var(--muted);font:10px var(--mono);margin-bottom:25px}.brief{font-size:15px;line-height:1.85}.example{white-space:pre-wrap;overflow-wrap:anywhere;background:var(--soft);border-left:3px solid var(--line);padding:17px 20px;font:12px/1.85 var(--mono);border-radius:0 8px 8px 0}.constraints{font-size:12px;color:var(--muted)}.source{display:inline-block;font-size:11px;margin-bottom:5px}.steps{display:flex;gap:28px;border-top:1px solid var(--line);padding-top:25px;margin:28px 0 23px;font-size:11px;color:var(--muted)}.steps b{display:inline-grid;place-items:center;width:23px;height:23px;background:var(--soft);border-radius:50%;margin-right:7px;font:11px var(--mono)}.field-label{font-size:12px;font-weight:600;display:block;margin-bottom:8px}.field-label > span:not([data-i18n]){font-weight:400;color:var(--muted);font-size:10px;margin-left:6px}textarea{display:block;width:100%;resize:vertical;background:var(--paper);color:var(--ink);border:1px solid var(--line);border-radius:6px;padding:13px 15px;line-height:1.7;font-size:13px;min-height:85px}textarea::placeholder,input::placeholder{color:var(--muted);opacity:1}#notes{background:linear-gradient(var(--paper),var(--paper));margin-bottom:24px}#code{font:12px/1.8 var(--mono);tab-size:2;background:var(--bg);white-space:pre;min-height:200px}.editor-heading{display:flex;align-items:center;justify-content:space-between;margin-bottom:8px}.editor-heading .field-label{margin:0}.subtle{border:0;background:transparent;font-size:10px;text-decoration:underline}.run-bar{display:flex;align-items:center;gap:15px;margin:14px 0}.run-bar .primary{font-size:12px}.run-bar>span{font-size:10px;color:var(--muted)}#test-results{font:11px/1.8 var(--mono);overflow-wrap:anywhere}.test-summary{font-family:var(--sans);font-size:12px;font-weight:600;margin:18px 0 8px}.test-pass{color:var(--ok)}.test-fail{color:var(--bad)}.help-bar{margin-top:30px;padding-top:24px;border-top:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;gap:15px}.help-bar strong{font-size:13px}.help-bar p{color:var(--muted);font-size:11px;margin:3px 0 0}.help-bar button{font-size:11px;white-space:nowrap}.help-bar button span{color:var(--muted);margin-left:8px}#hints{padding-left:23px;font-size:13px;color:var(--muted)}#hints li{padding:6px 0}.review-toggle{display:flex;justify-content:space-between;width:100%;margin-top:24px;padding:14px 0;border:0;border-top:1px solid var(--line);border-bottom:1px solid var(--line);border-radius:0;background:transparent;font-weight:600;font-size:13px}.review-note{font-size:11px;color:var(--muted);margin:18px 0}#solution{font-size:14px;line-height:1.9}#reference{font-size:12px;margin-bottom:20px}#reference summary{cursor:pointer}#reference-code{font:11px/1.8 var(--mono);white-space:pre-wrap;overflow-wrap:anywhere;background:var(--bg);padding:15px;border-radius:6px}#rubric{display:flex;flex-direction:column;gap:12px;margin:20px 0}#rubric label{display:flex;align-items:start;gap:10px;font-size:12px}input[type=checkbox]{accent-color:var(--accent);margin-top:5px}#reflection{margin-bottom:15px}#complete{font-size:12px}.workspace-foot{display:flex;justify-content:space-between;gap:10px;flex-wrap:wrap;margin-top:30px;font-size:9px;color:var(--muted)}.further{display:grid;grid-template-columns:1fr 1fr;gap:60px;padding:65px 0}.further h2{font:32px/1.2 Georgia;margin:0}.further a{display:flex;justify-content:space-between;border-bottom:1px solid var(--line);padding:12px 0;text-decoration:none;font-size:13px}.further p{color:var(--muted);font-size:10px;margin-top:15px}footer{display:flex;justify-content:space-between;align-items:center;gap:15px;border-top:1px solid var(--line);padding-top:25px;padding-bottom:30px;font-size:11px;color:var(--muted)}footer button{font-size:11px;background:transparent;border:0;padding:0}dialog{max-width:570px;width:calc(100% - 32px);max-height:85dvh;overflow:auto;background:var(--paper);color:var(--ink);border:1px solid var(--line);border-radius:10px;padding:28px;box-shadow:0 25px 100px #0004}dialog::backdrop{background:#10253799}.dialog-heading{display:flex;align-items:start;justify-content:space-between;gap:20px}.dialog-heading h2{font:28px/1.2 Georgia}.dialog-heading button{border:0;padding:0;background:transparent}dialog p,dialog li{font-size:13px}dialog hr{border:0;border-top:1px solid var(--line);margin:25px 0}dialog input[type=file]{max-width:100%;font-size:12px;margin:10px 0}#import-status{color:var(--accent)}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%)}.skip{position:absolute;top:-100px;left:20px;background:var(--paper);padding:10px;z-index:10}.skip:focus{top:10px}[hidden]{display:none!important}
@media(max-width:1100px){.top,main,footer{padding-left:28px;padding-right:28px}.workbench{grid-template-columns:245px minmax(0,1fr)}.workspace{padding:26px}.intro{grid-template-columns:1fr 260px}.edition{display:none}}
@media(max-width:850px){.workbench{grid-template-columns:minmax(0,1fr)}.library{border-right:0;border-bottom:1px solid var(--line)}#tracks{flex-direction:row;flex-wrap:wrap;gap:5px}#tracks button{padding:6px 8px;font-size:11px}.queue{width:auto;gap:20px}.library-caption{margin-top:16px}#exercise-list{flex-direction:row;max-height:none;overflow-x:auto;max-width:100%;padding-bottom:8px}.exercise-card{min-width:195px;max-width:195px;border-left:0;border-bottom:3px solid transparent}.exercise-card[aria-current=true]{border-bottom-color:var(--accent)}.library-foot{margin-top:12px}.intro{gap:25px;grid-template-columns:1fr 230px}.session-card{padding:20px}.session-card p{font-size:25px}.further{gap:30px}}
@media(max-width:600px){.top,main,footer{padding-left:18px;padding-right:18px}.top{height:76px}.brand{font-size:19px}.brand-mark{width:32px;height:32px;font-size:24px}.top-actions{gap:7px}.top-actions button{font-size:10px;padding:6px 9px}.top-actions a{font-size:10px;padding-left:0}.top-actions #theme span{display:none}.intro{grid-template-columns:1fr;padding:35px 0 30px;gap:25px}h1{font-size:48px}.lede{font-size:14px}.session-card{transform:none;padding:17px;display:grid;grid-template-columns:1fr 1fr;gap:10px}.session-card .label{grid-column:1/-1;font-size:9px}.session-card p{font-size:22px;margin:0}.session-card small{grid-column:1/-1;margin:0}.session-card .primary{font-size:11px;gap:10px;align-self:center}.workspace{padding:22px 18px}.exercise-top{gap:8px;margin-bottom:23px}.exercise-top .label{font-size:9px;letter-spacing:1px}.exercise-top button{font-size:10px;padding:6px 8px}.exercise-heading{gap:10px}.exercise-heading h2{font-size:28px}.exercise-number{font-size:20px}.exercise-meta{font-size:9px;gap:9px}.brief{font-size:14px}.example{padding:12px;font-size:11px}.steps{gap:20px;font-size:10px}.field-label > span:not([data-i18n]){display:block;margin:3px 0 0}.run-bar{align-items:flex-start;flex-direction:column;gap:8px}.help-bar{align-items:flex-start;flex-direction:column;gap:12px}.further{grid-template-columns:1fr;gap:20px;padding:40px 0}.further h2{font-size:28px}footer{flex-wrap:wrap;font-size:10px}.workspace-foot{font-size:9px}.library{min-width:0;padding:18px 13px}.brand{gap:7px}dialog{padding:22px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important;animation:none!important;transition:none!important}}
.language-picker{font-size:10px;color:var(--muted);display:flex;align-items:center;gap:6px}.language-picker select{font:12px var(--sans);padding:5px 7px;border:1px solid var(--line);border-radius:5px;color:var(--ink);background:var(--paper)}.language-actions{display:flex;gap:15px;align-items:center;flex-wrap:wrap;font-size:11px}.language-actions button{font-size:11px}.editor-heading{flex-wrap:wrap;gap:10px}

#test-results { white-space: pre-wrap; overflow-wrap: anywhere; }

/* Portfolio family: compact controls, visible focus, quiet surfaces. */
#theme{width:38px;height:38px;min-height:38px;padding:0;border-radius:50%;display:inline-grid;place-items:center;font-size:20px;line-height:1;flex-shrink:0}
#theme span{display:none}
footer a{text-decoration:none;text-underline-offset:4px}footer a:hover{text-decoration:underline}
@media(hover:hover) and (prefers-reduced-motion:no-preference){button,a,input,select,textarea{transition:border-color 150ms ease,background-color 150ms ease,color 150ms ease}}

button.primary:hover{background:var(--ink);color:var(--paper);border-color:var(--ink)}

.dialog-heading button{width:32px;height:32px;min-width:32px;padding:0;color:var(--muted);font-size:17px;line-height:1}

.ui-language{display:flex;align-items:center;gap:.4rem;font-size:.75rem}.ui-language select{max-width:9rem;padding:.4rem;border:1px solid var(--line);border-radius:.4rem;background:var(--paper);color:inherit;font:inherit}.top-actions{flex-wrap:wrap}#content-language-note{border-left:2px solid currentColor;padding-left:.75rem}@media(max-width:600px){.top{flex-wrap:wrap;gap:1rem}.ui-language{width:100%}}

/* Keep touch form text readable without Safari focus zoom. Pinch zoom stays enabled. */
@media (pointer:coarse){input:not([type=checkbox]):not([type=radio]),select,textarea{font-size:16px!important}button,select{min-height:44px}dialog{overflow-y:auto;overscroll-behavior:contain}}

@media(max-width:600px){.top{height:auto;min-height:76px;padding-top:18px;padding-bottom:18px}.top-actions{width:100%}}

/* Motion preference: System follows the OS. On and Off are explicit visitor choices. */
.motion-control{white-space:nowrap;font-size:11px!important}.motion-off *,.motion-off *::before,.motion-off *::after{animation:none!important;transition:none!important;scroll-behavior:auto!important}@media(prefers-reduced-motion:reduce){html:not(.motion-force-on){scroll-behavior:auto}html:not(.motion-force-on) *,html:not(.motion-force-on) *::before,html:not(.motion-force-on) *::after{animation:none!important;transition:none!important}}