@import url('https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;600;700&family=Manrope:wght@400;500;600;650;700;800&family=IBM+Plex+Mono:wght@400;500&display=swap');
:root{--bg:#f7f8fa;--ink:#232d3c;--muted:#6e7788;--border:#e4e8ed;--green:#26795b;--mint:#e7f3ec;--purple:#7864b5}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font:14px 'DM Sans',sans-serif}button,a,textarea{outline-offset:4px}button{font:inherit;cursor:pointer}button{border:1px solid var(--border);background:white;color:var(--ink);border-radius:7px;padding:10px 14px}button:hover{border-color:#8b9d95;background:#f4f8f5}button:disabled{opacity:.5;cursor:wait}a{color:var(--green)}aside{position:fixed;width:251px;inset:0 auto 0 0;background:#fff;border-right:1px solid var(--border);padding:31px 20px 15px;display:flex;flex-direction:column;overflow:auto}.brand{display:flex;align-items:center;gap:12px;text-decoration:none;color:var(--ink);font:800 20px Manrope,sans-serif;padding:0 8px 35px}.brand small{display:block;font:9px 'DM Sans';letter-spacing:2.4px;color:var(--muted);margin-top:4px}.logo{background:#e4f1e9;color:#286047;border:1px solid #d9e9dd;border-radius:10px;width:44px;height:45px;padding:8px;font:600 24px Manrope;position:relative}.logo span{position:absolute;font:13px sans-serif;right:5px;top:3px}.path-title,.sidebar-label{font-size:9px;letter-spacing:1.7px;color:#89919d;font-weight:700}.path-title{display:flex;justify-content:space-between;padding:0 10px 14px}.nav-main{display:flex;align-items:center;gap:12px;width:100%;border:0;background:transparent;margin-bottom:6px;text-align:left}.nav-main.active{background:var(--mint);color:#286a50}.pill{font-size:10px;border:1px solid #d3e1d9;border-radius:4px;padding:1px 5px;margin-left:auto}.sidebar-label{margin:25px 10px 10px}nav button{width:100%;border:0;display:flex;align-items:center;text-align:left;font-size:11px;gap:10px;padding:10px 8px;color:#737c8b;background:transparent;margin:1px 0}nav button .num{font:10px 'IBM Plex Mono';width:21px;height:21px;border:1px solid #e4e7eb;display:grid;place-items:center;border-radius:50%;color:#9197a1;flex-shrink:0}nav button.active{color:#246d51;background:#edf5f0;font-weight:600}nav button.active .num{color:white;background:var(--green);border-color:var(--green)}nav button .done{margin-left:auto;color:var(--green)}.progress-card{margin-top:auto;background:#f7f9f8;border:1px solid #e6ece8;border-radius:9px;padding:13px 12px}.progress-card>div:first-child{display:flex;justify-content:space-between;font-size:9px}.progress-card b{font-size:9px;color:var(--green)}.progress-track{height:4px;background:#e4eae6;border-radius:4px;margin-top:13px;overflow:hidden}.progress-track i{display:block;background:#4b9b74;height:100%;width:0}.progress-card p{font-size:10px;color:var(--muted);line-height:1.5}.progress-card button{font-size:10px;width:100%;padding:8px}.settings{border:0;font-size:10px;color:var(--muted);padding:19px 0 0}.page{margin-left:251px}header{height:75px;border-bottom:1px solid var(--border);background:#fff;display:flex;align-items:center;padding:0 39px;gap:22px;font-size:10px;color:var(--muted)}header>div:first-child{letter-spacing:1px}header>div:first-child span{letter-spacing:0;margin-left:14px}header button{border:0;font-size:11px;padding:6px}.saved{margin-left:auto;font-size:10px;display:flex;align-items:center;gap:7px}i:not(.file-icon){font-style:normal}.saved i,.live i{display:inline-block;width:6px;height:6px;background:#58a17c;border-radius:50%}main{max-width:1430px;margin:auto;padding:36px 40px 20px}.intro-row{display:flex;justify-content:space-between;align-items:center}.eyebrow{font-size:9px;color:var(--green);letter-spacing:1.5px;font-weight:700}.eyebrow span{color:#969da8;margin-left:7px}h1{font:800 clamp(26px,2.4vw,37px) Manrope,sans-serif;letter-spacing:-1.5px;margin:11px 0 9px}h1 span{color:var(--green)}.subtitle{color:var(--muted);font-size:12px;margin:0}.duration{display:flex;align-items:center;gap:10px;color:var(--muted);font-size:21px;padding-top:12px}.duration span{font-size:11px;line-height:1.7}.duration small{font-size:9px;color:#9299a4}.steps{display:flex;gap:0;border-bottom:1px solid var(--border);margin:28px 0 24px;justify-content:space-between}.steps button{border:0;border-bottom:2px solid transparent;border-radius:0;background:transparent;display:flex;gap:8px;padding:0 4px 13px;color:#89919d;font-size:10px;align-items:center}.steps button span{border:1px solid #dee3e8;border-radius:50%;width:19px;height:19px;display:grid;place-items:center;font-size:9px}.steps button.active{color:var(--green);border-bottom-color:var(--green);font-weight:700}.steps button.active span{background:var(--green);color:#fff;border-color:var(--green)}.understand{background:#eef5f1;border:1px solid #deebe3;border-radius:9px;display:flex;gap:15px;padding:19px 20px;position:relative;min-height:102px}.concept-icon{background:white;border:1px solid #dbe9df;width:33px;height:33px;display:grid;place-items:center;border-radius:8px;color:var(--green);font-size:22px;flex-shrink:0}.understand h2{font:700 14px Manrope;margin:0 0 7px}.understand p{font-size:11px;line-height:1.8;max-width:810px;margin:0;color:#53675d;padding-right:25px}.concept-tag{font-size:8px;letter-spacing:1px;color:#779083;position:absolute;right:17px;top:19px}.lesson-layout{display:grid;grid-template-columns:1.18fr 1fr;gap:18px;margin-top:20px}.code-panel,.visual-panel{background:white;border:1px solid var(--border);border-radius:10px;overflow:hidden}.panel-head{height:49px;border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;padding:0 17px;font-size:11px}.panel-head>span:first-child{display:flex;align-items:center;gap:9px}.file-icon{background:#f6edc9;color:#8a7835;font:600 8px 'IBM Plex Mono';padding:3px;border-radius:3px}.editable{font-size:9px;color:#8993a1}.editor-wrap{display:flex;height:236px;padding:23px 0;overflow:auto;background:#fff}#line-numbers{font:12px/25px 'IBM Plex Mono',monospace;color:#a9b0bc;text-align:right;width:43px;flex-shrink:0;padding-right:15px}#line-numbers div.current{color:var(--green);font-weight:700;background:var(--mint)}.code-layer{position:relative;flex:1;min-width:0}#highlight,#editor{font:12px/25px 'IBM Plex Mono',monospace;white-space:pre;tab-size:2;margin:0;border:0;padding:0 12px 0 0;min-height:100%;width:100%}#highlight{pointer-events:none;color:#455368}#editor{position:absolute;inset:0;resize:none;background:transparent;color:transparent;caret-color:#233426;overflow:auto;outline-offset:0}#editor::selection{background:#b8d9ed80}.kw{color:#9871b4}.str{color:#3a8b64}.number{color:#b17a3d}.comment{color:#9aa3af}.code-actions{display:flex;align-items:center;gap:8px;padding:12px 14px;border-top:1px solid #f0f2f4;white-space:nowrap}.code-actions button{font-size:10px;padding:10px 11px}.primary{background:var(--green);color:white;border-color:var(--green)}.primary:hover{background:#1b6046;color:white}.primary kbd{background:#ffffff20;color:#c8e1d3;padding:2px 4px;border-radius:3px;margin-left:9px;font:9px sans-serif}.code-actions .reset{margin-left:auto;border:0;padding:6px;color:#8b94a1;font-size:15px}.reset span{font-size:9px}.console-head{padding:10px 16px;background:#f9fafb;border-top:1px solid var(--border);border-bottom:1px solid #edf0f3;display:flex;justify-content:space-between;align-items:center;font-size:9px;letter-spacing:1px;color:#6c7788}.console-head button{border:0;padding:0;background:none;font-size:9px;color:#85909d}#console{height:112px;overflow:auto;padding:14px 17px;font:11px/1.9 'IBM Plex Mono',monospace}.muted{color:#909aa8}#console .output{display:flex;gap:12px}#console .output:before{content:'›';color:#83a591}.error{color:#ae493d;background:#fff0ed;padding:9px;border-radius:5px}.visual-panel{display:flex;flex-direction:column}.live{font-size:8px;letter-spacing:1px;color:#6f907e;display:flex;gap:6px;align-items:center}.visual-caption{padding:25px 23px 0}.mini-label{font-size:8px;color:#929aa5;letter-spacing:1.3px;font-weight:600}.visual-caption p{font-size:12px;color:#737e8d;line-height:1.8;margin:10px 0}#variables{padding:12px 23px;display:flex;gap:12px;flex-wrap:wrap;align-content:center;flex:1}.var{border:1px solid #dce7e1;border-radius:8px;min-width:115px;max-width:100%;padding:12px 14px;background:#f9fcfa;align-self:center}.var .var-name{font:11px 'IBM Plex Mono';color:#458269}.var .value{font:500 24px 'IBM Plex Mono';padding:15px 0 12px;overflow-wrap:anywhere}.var .type{font-size:8px;letter-spacing:.5px;color:#7d9387;border-top:1px solid #e2eae5;padding-top:8px;display:flex;gap:12px}.var.changed{box-shadow:0 0 0 2px #8dbb9c}.var.string{background:#faf8fd;border-color:#e7dff2}.var.string .var-name{color:#8b72af}.var.boolean{background:#fffaf0;border-color:#eee4cc}.array-items{display:flex;gap:5px;flex-wrap:wrap;margin:12px 0}.array-item{padding:7px;background:white;border:1px solid var(--border);border-radius:4px;font:11px monospace}.array-item small{display:block;color:var(--muted);font:8px sans-serif;margin-top:7px}.object-row{font:11px/2 monospace}.trace-footer{display:flex;justify-content:space-between;margin:17px 20px 0;padding:13px 0;border-top:1px solid #edf0f2;color:#8a95a0;font-size:9px}#dom-preview{padding:12px 23px}#dom-preview code{font-size:9px;line-height:1.7;color:var(--muted)}.mini-page{padding:15px;border:1px solid var(--border);border-radius:6px;margin:10px 0;background:#f8faf9}.mini-page strong{padding-right:20px}.activity{margin-top:18px}.activity:empty{display:none}.activity-box{background:white;border:1px solid var(--border);border-radius:9px;padding:20px}.activity h3{font:700 14px Manrope;margin:0 0 9px}.activity p{font-size:12px;color:#657285;line-height:1.8}.choices{display:flex;gap:10px;margin-top:12px}.choices button{font:12px monospace;flex:1}.feedback{margin-top:12px;font-size:12px;line-height:1.8;color:#2f7756}.test-row{padding:8px 10px;border:1px solid var(--border);border-radius:5px;margin:6px 0;font-size:11px}.test-row.fail{color:#ab4b3f}.test-row.pass{color:var(--green)}.hints{display:flex;gap:8px;margin-top:15px;flex-wrap:wrap}.hint{font-size:12px;background:#f5f5fb;padding:13px;margin-top:12px;border-radius:5px;white-space:pre-wrap;line-height:1.7}.experiment{display:flex;gap:15px;align-items:center;border:1px solid #e4e8ec;background:#fff;border-radius:8px;margin-top:20px;padding:17px 20px}.bulb{color:#9f9055;background:#f8f4e5;border-radius:8px;width:33px;height:33px;display:grid;place-items:center;font-size:19px}.experiment h3{font-size:11px;margin:0 0 5px}.experiment p{font-size:10px;color:#85909c;margin:0;line-height:1.7}.experiment code{color:#6c587f;background:#f4f0f8;padding:2px 4px;border-radius:3px}.experiment>span:last-child{margin-left:auto;font-size:9px;color:#a1a7b0;font-style:italic}footer{display:flex;align-items:center;justify-content:space-between;border-top:1px solid var(--border);padding-top:20px;margin-top:27px}footer>span{font-size:10px;color:#9aa3ad}footer button{background:var(--green);color:white;border:0;font-size:11px;padding:12px 18px}footer button:hover{background:#1b6046;color:#fff}footer button span{margin-left:17px}.source{font-size:9px;color:#9aa3ad;margin-top:24px}.source a{color:#7b8f85}dialog{border:1px solid var(--border);border-radius:13px;max-width:650px;width:90%;padding:27px;line-height:1.8;box-shadow:0 15px 70px #162c3330}dialog::backdrop{background:#26362d55}dialog h2{font:700 21px Manrope}dialog p,dialog li{font-size:13px}dialog button{margin:7px 6px 0 0}dialog pre{font:11px/1.8 monospace;background:#f5f7f8;padding:15px;white-space:pre-wrap}.skip{position:fixed;top:-100px;z-index:9;background:white;padding:10px}.skip:focus{top:0}.empty-visual{width:100%;display:flex;justify-content:center;align-items:center;gap:18px;font:24px monospace;color:#aec2b6}.empty-visual span{padding:22px;border:1px dashed #bdcec3;border-radius:12px;color:var(--green)}@media(min-width:1450px){main{padding-top:45px}.editor-wrap{height:280px}.understand p{font-size:12px}nav button{font-size:12px;padding-block:12px}.sidebar-label{margin-top:30px}}@media(max-width:1150px){aside{width:220px;padding-inline:13px}.page{margin-left:220px}main{padding:30px 24px}header{padding-inline:24px}.editable,.reset span,.primary kbd{display:none}.code-actions button{padding:9px 8px}.experiment>span:last-child{display:none}}@media(max-width:850px){aside{width:180px;padding-inline:10px}.page{margin-left:180px}.brand{font-size:16px;padding-left:0}.brand small{font-size:8px}.lesson-layout{grid-template-columns:1fr}.visual-panel{min-height:300px}nav button{font-size:10px;gap:6px}.saved{display:none}.duration{display:none}.steps button{font-size:9px;gap:4px}.concept-tag{display:none}}@media(max-width:600px){aside{position:relative;width:100%;padding:14px;display:block;max-height:none}.brand{padding:0;font-size:18px}.logo{width:37px;height:37px;font-size:19px}.path-title,.sidebar-label,.progress-card,.settings{display:none}.nav-main{display:inline-flex;width:auto;margin:14px 10px 0 0;padding:7px}.pill{margin-left:5px}nav{display:flex;overflow:auto;margin-top:8px;gap:5px}nav button{width:auto;white-space:nowrap;padding:5px 8px}nav button .num{width:18px;height:18px}.page{margin-left:0}header{height:45px;padding:0 18px}main{padding:25px 17px}.steps{overflow:auto;gap:15px}.steps button{white-space:nowrap}.understand{padding:15px;gap:10px}.understand p{padding:0}.experiment{padding:14px}.editor-wrap{height:250px}.visual-caption{padding:18px}footer>span{max-width:125px;line-height:1.7}.choices{flex-wrap:wrap}}@media(prefers-reduced-motion:no-preference){button{transition:background .15s,border-color .15s}.var.changed{animation:glow .45s ease-out}@keyframes glow{from{background:#dbf1e4}to{}}} 
/* Comfortable reading at laptop sizes. */
.understand p{font-size:13px;line-height:1.85}.understand h2{font-size:15px}.subtitle{font-size:13px}.visual-caption p{font-size:13px}.activity p{font-size:13px}.experiment p{font-size:12px}.experiment h3{font-size:12px}.steps button{font-size:11px}nav button{font-size:12px}#highlight,#editor,#line-numbers{font-size:13px}#console{font-size:12px}.visual-panel .panel-head b{font-size:12px}.code-layer{overflow:hidden}@media(max-width:600px){.settings{display:inline-block;padding:8px;margin-top:5px}.understand p{font-size:12px}nav button{font-size:11px}.steps button{font-size:10px}}
.prediction-code{font:12px/1.8 'IBM Plex Mono',monospace;white-space:pre-wrap;background:#f6f8fa;border:1px solid var(--border);border-radius:6px;padding:15px;color:#566777}.budget{margin-top:15px}.budget label{font-size:12px;display:inline-flex;flex-direction:column;gap:7px;margin:8px 12px 12px 0}.budget input{font:13px 'IBM Plex Mono',monospace;padding:9px 12px;border:1px solid #d5dfd9;border-radius:5px;max-width:210px}.budget button{font-size:12px}