:root{--ground:#fff;--surface:#f6f7f5;--text:#1f201d;--muted:#636361;--border:#e6e8e3;--accent:#1b6e66;--soft:#edf3f1;--gap:16px;font-family:'Instrument Sans',system-ui,sans-serif;color:var(--text);background:var(--ground);font-synthesis:none}
*{box-sizing:border-box}body{margin:0;font-size:14px;line-height:1.5}button,a{-webkit-tap-highlight-color:transparent}button{font:inherit;color:inherit;cursor:pointer}button:disabled{cursor:not-allowed}a{color:inherit;text-decoration:none}button:focus-visible,a:focus-visible{outline:3px solid var(--accent);outline-offset:4px}button{touch-action:manipulation}svg{width:19px;height:19px;flex-shrink:0}h1,h2,h3,p{margin:0}h1,h2,h3{font-weight:500}h1:focus,h2:focus,.answer:focus,main:focus{outline:none}button{border:0}progress{appearance:none;border:0;width:100%;height:5px;display:block;background:var(--border);border-radius:5px;overflow:hidden}progress::-webkit-progress-bar{background:var(--border)}progress::-webkit-progress-value{background:var(--accent);border-radius:5px}progress::-moz-progress-bar{background:var(--accent);border-radius:5px}[hidden]{display:none!important}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.skip{position:fixed;top:-80px;left:16px;padding:12px 20px;z-index:10;background:var(--text);color:white}.skip:focus{top:12px}
.sidebar{overflow-y:auto;position:fixed;inset:0 auto 0 0;width:238px;padding:32px 20px 24px;border-right:1px solid var(--border);display:flex;flex-direction:column;background:var(--ground);z-index:5}.brand{display:flex;align-items:center;gap:10px;font-size:22px;font-weight:600;letter-spacing:-.7px}.brand-mark{font-family:'Instrument Serif',Georgia,serif;font-size:37px;line-height:1;color:var(--accent);letter-spacing:-3px;margin-right:3px}.sidebar-subtitle{font-size:12px;color:var(--muted);margin:13px 0 34px}.nav-home{display:flex;align-items:center;gap:10px;padding:11px 12px;border-radius:8px;width:100%;text-align:left;background:transparent}.selected{background:#eef0ec!important}.nav-label{font-size:12px;color:var(--muted);margin:30px 12px 12px}.nav-topic{display:flex;align-items:center;gap:10px;min-height:46px;width:100%;background:transparent;text-align:left;border-radius:8px;padding:9px 9px;font-size:13px}.nav-topic>span:nth-child(2){flex:1}.nav-topic>svg{width:13px;color:var(--muted)}.nav-topic:disabled{color:#63675f}.nav-topic:not(:disabled):hover,.nav-home:hover{background:var(--surface)}.nav-number{font-size:11px;width:22px;flex-shrink:0;color:var(--muted);font-variant-numeric:tabular-nums}.nav-number svg{width:16px;display:block}.nav-number.done{color:var(--accent)}.sidebar-bottom{margin-top:auto;padding:44px 10px 0}.mini-progress{display:flex;justify-content:space-between;font-size:11px;margin-bottom:10px;color:var(--muted);font-variant-numeric:tabular-nums}.sidebar-bottom p{margin-top:20px;font-size:13px;line-height:1.7;color:var(--muted)}.local-label{display:block;font-size:11px;color:var(--muted);margin-top:28px}.local-label span{color:var(--accent);margin-right:4px}.mobile-header{display:none}
/* 12 columns share a 16px gutter. Main panels span 9/3; curriculum rows span 6/6. */
main{margin-left:238px;padding:33px clamp(28px,4.2vw,72px) 28px;max-width:1482px;min-height:100vh}.page-top{display:flex;align-items:center;justify-content:space-between;gap:16px;color:var(--muted);font-size:12px;min-height:24px}.separator{margin:0 10px;color:#9b9e96}.page-heading{margin:39px 0 29px}.page-heading h1{font:400 clamp(38px,4vw,54px)/1.02 'Instrument Serif',Georgia,serif;letter-spacing:-1.2px}.page-heading p{font-size:14px;line-height:1.7;color:var(--muted);margin-top:17px}.overview-grid{display:grid;grid-template-columns:repeat(12,minmax(0,1fr));gap:var(--gap)}.continue-panel{grid-column:span 9;display:grid;grid-template-columns:1fr 1fr;gap:22px;padding:25px;background:var(--surface);border-radius:20px;min-width:0}.eyebrow{font-size:12px;color:var(--muted)}.continue-copy h2{font-size:23px;letter-spacing:-.6px;line-height:1.25;margin:12px 0 8px}.continue-copy p{color:var(--muted);font-size:12px;max-width:220px}.lesson-meta{display:flex;gap:15px;font-size:11px;color:var(--muted);margin:17px 0 22px}.lesson-meta span+span{border-left:1px solid #cdd1c9;padding-left:15px}.primary,.secondary{min-height:44px;padding:11px 18px;border-radius:24px;display:inline-flex;align-items:center;justify-content:center;gap:10px;font-size:13px;font-weight:500;transition:background .15s}.primary{background:var(--text);color:#fff}.primary:hover{background:#3d4037}.secondary{background:#eff0ec;color:var(--text)}.secondary:hover{background:#e1e5df}.primary svg,.secondary svg{width:17px}.hello-code{background:#202923;border-radius:12px;align-self:stretch;min-width:0;color:#e3e8df;padding:17px 18px;display:flex;flex-direction:column}.code-caption{display:flex;justify-content:space-between;font-size:11px;color:#b0bbb3}.hello-code pre{font-size:clamp(11px,.86vw,12px);line-height:1.8;overflow:auto;margin:21px 0 16px;flex:1}.hello-code code{font-family:ui-monospace,SFMono-Regular,Consolas,monospace}.code-muted{color:#a9b8ab}.code-type{color:#b6d3be}.code-string{color:#e1d3a5}.code-output{border-top:1px solid #48544b;padding-top:12px;font:11px ui-monospace,monospace}.code-output span{margin-right:8px}.journey-panel{grid-column:span 3;background:var(--surface);border-radius:20px;padding:25px 20px;min-width:0}.big-number{font-size:43px;line-height:1;margin:18px 0 5px;font-weight:400;letter-spacing:-1px;font-variant-numeric:tabular-nums}.big-number span{font-size:22px;color:var(--muted)}.journey-panel>p{font-size:12px;color:var(--muted)}.topic-track{display:flex;gap:4px;margin:23px 0 8px}.topic-track span{height:6px;flex:1;background:#dfe4dc;border-radius:2px}.topic-track .filled{background:var(--accent)}.progress-caption{font-size:11px;color:var(--muted)}.journey-panel .journey-note{font-size:11px;line-height:1.7;margin-top:17px}.curriculum{margin-top:33px}.section-heading{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-bottom:18px}.section-heading h2{font-size:17px;letter-spacing:-.4px}.section-heading p{font-size:12px;color:var(--muted);margin-top:5px}.topic-count{font-size:11px;color:var(--muted);white-space:nowrap}.topic-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));column-gap:30px}.topic-row{display:flex;align-items:flex-start;text-align:left;gap:15px;min-height:101px;border-top:1px solid var(--border);padding:17px 4px;background:transparent;width:100%;border-radius:0}.topic-row:not(:disabled):hover{background:var(--surface)}.topic-index{font:20px 'Instrument Serif',Georgia,serif;color:#7a8076;min-width:25px;padding-top:1px;font-variant-numeric:tabular-nums}.topic-content{flex:1;min-width:0;display:flex;flex-direction:column}.topic-title{font-size:14px;font-weight:500;line-height:1.4}.topic-description{font-size:12px;color:var(--muted);margin-top:3px;line-height:1.6}.topic-status{font-size:11px;color:var(--accent);margin-top:8px}.topic-row.is-locked .topic-status{color:#63675f}.topic-row.is-locked .topic-title{color:#63675f}.topic-row.is-locked .topic-description{color:#63675f}.topic-trailing{padding-top:4px;color:#72796f}.topic-trailing svg{width:16px}.is-open .topic-trailing,.is-done .topic-trailing{color:var(--accent)}.page-footer{margin-top:18px;padding-top:18px;border-top:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;gap:12px;font-size:11px;color:var(--muted)}.text-button{display:inline-flex;align-items:center;gap:8px;background:none;padding:8px 0;min-height:38px;font-size:12px;color:var(--muted)}.text-button:hover{color:var(--text)}.guide{margin-top:20px;background:var(--surface);border-radius:16px;padding:24px}.guide h2{font-size:18px}.guide ol{padding-left:20px;line-height:2;color:var(--muted)}.guide p{font-size:12px;line-height:1.8;color:var(--muted)}
.lesson-heading{margin:39px 0 32px}.lesson-heading h1{font:400 43px/1.1 'Instrument Serif',Georgia,serif;letter-spacing:-.8px}.lesson-heading p{margin-top:12px;color:var(--muted);font-size:13px}.study-layout{display:grid;grid-template-columns:minmax(0,3fr) minmax(180px,1fr);gap:32px}.study-main{min-width:0}.study-progress{display:flex;justify-content:space-between;font-size:11px;color:var(--muted);margin-bottom:12px;gap:10px}.flashcard{background:var(--surface);border-radius:20px;padding:28px;margin-top:22px;overflow:hidden}.flashcard-top{display:flex;justify-content:space-between;gap:10px;color:var(--muted);font-size:11px}.flashcard h2{font-size:23px;line-height:1.45;letter-spacing:-.5px;margin-top:31px;font-weight:500;overflow-wrap:anywhere}.question-code{background:#202923;color:#e1e9df;border-radius:12px;padding:22px 20px;overflow-x:auto;line-height:1.9;font-size:13px;margin:25px 0 0;max-width:100%;tab-size:4}.question-code code{font-family:ui-monospace,SFMono-Regular,Consolas,monospace}.concept-symbol{font-family:'Instrument Serif',Georgia,serif;font-size:74px;line-height:1;color:#9daf9e;margin:24px 0}.reveal-area{margin-top:28px;display:flex;justify-content:space-between;align-items:center;gap:12px;border-top:1px solid #dce1d7;padding-top:20px}.reveal-area p{font-size:12px;color:var(--muted)}.answer{border-top:1px solid #dce1d7;margin-top:25px;padding-top:23px}.answer h3{font-size:19px;line-height:1.5;margin-top:9px}.answer p{color:var(--muted);font-size:13px;line-height:1.85;margin-top:12px;overflow-wrap:anywhere}.rating-area{margin-top:23px}.rating-area>p{text-align:center;font-size:12px;color:var(--muted);margin-bottom:12px}.rating-buttons{display:grid;grid-template-columns:1fr 1fr;gap:12px}.rating-buttons button{min-height:49px}.rating-buttons .primary{background:var(--accent)}.rating-buttons .primary:hover{background:#15554f}kbd{font:11px inherit;border:1px solid currentColor;opacity:.65;border-radius:3px;padding:0 4px;margin-left:auto}.study-hint{font-size:11px;color:var(--muted);text-align:center;margin-top:20px}.lesson-aside{padding-top:1px}.lesson-aside h2{font-size:13px;margin-bottom:18px}.card-list{list-style:none;padding:0;margin:0}.card-list li{display:flex;align-items:center;gap:12px;font-size:12px;padding:12px 0;border-bottom:1px solid var(--border);color:var(--muted)}.card-list li>span:first-child{width:20px;flex-shrink:0;font-size:11px}.card-list small{display:block;font-size:11px;margin-top:2px;color:var(--muted)}.card-list .current{color:var(--text);font-weight:600}.card-list .current>span:first-child{color:var(--accent)}.card-list .finished>span:first-child{color:var(--accent)}.card-list svg{width:15px;height:15px}.learning-note{background:var(--soft);padding:20px;border-radius:16px;margin-top:28px}.note-mark{font:30px 'Instrument Serif',Georgia,serif;color:var(--accent)}.learning-note h3{font-size:13px;margin:13px 0 7px}.learning-note p,.local-note{font-size:11px;line-height:1.8;color:var(--muted)}.local-note{margin:18px 4px}.summary{max-width:620px;text-align:center;margin:60px auto 0}.summary-symbol{margin:0 auto 25px;color:var(--accent)}.summary-symbol svg{width:54px;height:54px}.summary h1{font:400 48px/1.1 'Instrument Serif',Georgia,serif;margin:14px 0 20px;letter-spacing:-1px}.summary>p:not(.eyebrow){color:var(--muted);font-size:14px;line-height:1.8}.session-stats{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));padding:25px 0;margin:30px 0;border-top:1px solid var(--border);border-bottom:1px solid var(--border)}.session-stats span{font-size:29px;font-variant-numeric:tabular-nums;display:block}.session-stats small{font-size:11px;color:var(--muted)}.next-preview{margin:25px 0}.next-preview>span{color:var(--accent);font-size:11px}.next-preview h2{font-size:22px;margin:9px 0 5px}.next-preview p{font-size:12px;color:var(--muted)}.summary-repeat{display:flex;margin:12px auto}.summary>.primary{margin-top:10px}.storage-notice{position:fixed;bottom:16px;left:calc(238px + 24px);right:24px;background:#fffbeb;border:1px solid #dfc784;border-radius:10px;padding:15px 20px;color:#73551b;font-size:12px;z-index:8}.noscript{margin:30px;padding:20px;background:#fffbeb}
@media(min-width:1600px){main{margin-right:auto;margin-left:max(238px,calc((100vw - 1100px)/2))}}
@media(max-width:1150px){.continue-panel{grid-column:span 8;grid-template-columns:1fr}.hello-code{display:none}.journey-panel{grid-column:span 4}.continue-copy p{max-width:none}.study-layout{grid-template-columns:minmax(0,1fr) 190px;gap:22px}.topic-description{font-size:12px}.flashcard{padding:24px}}
@media(max-width:900px){.sidebar{width:210px;padding:28px 18px}.sidebar-subtitle{font-size:11px}main{margin-left:210px;padding:28px 26px}.nav-topic{font-size:13px;gap:6px}.topic-grid{grid-template-columns:1fr}.topic-row{min-height:93px}.study-layout{grid-template-columns:1fr}.lesson-aside{display:none}.page-heading h1{font-size:46px}.storage-notice{left:230px}}
@media(max-width:640px){.mobile-header{display:flex;position:sticky;top:0;background:white;z-index:7;padding:10px 18px;align-items:center;justify-content:space-between;border-bottom:1px solid var(--border);min-height:65px}.mobile-header .brand{font-size:20px}.mobile-header .brand-mark{font-size:32px}#menu-toggle{display:flex;align-items:center;gap:7px;background:var(--surface);border-radius:20px;min-height:40px;padding:7px 14px;font-size:12px}#menu-toggle span{margin-left:7px}.sidebar{display:none;position:fixed;top:65px;width:100%;bottom:0;overflow:auto;padding:18px 22px}.sidebar.mobile-open{display:flex}.desktop-brand,.sidebar-subtitle{display:none}.nav-label{margin-top:22px}.nav-topic{min-height:43px;font-size:13px}.sidebar-bottom{padding-top:24px;margin-top:20px}.sidebar-bottom p{display:none}.local-label{margin-top:15px}.sidebar nav{display:grid;grid-template-columns:1fr 1fr;gap:6px}main{margin:0;padding:22px 18px 25px;min-height:calc(100vh - 65px)}.page-top{font-size:11px}.page-heading{margin:29px 0 24px}.page-heading h1{font-size:43px;letter-spacing:-1px}.page-heading p{font-size:13px;margin-top:14px}.overview-grid{gap:12px}.continue-panel{grid-column:span 8;padding:20px 17px;border-radius:16px;gap:0}.continue-copy h2{font-size:22px;margin-top:12px}.continue-copy p{font-size:11px}.continue-copy .eyebrow{font-size:11px}.lesson-meta{gap:9px;font-size:11px;margin:16px 0 19px}.lesson-meta span+span{padding-left:9px}.continue-copy .primary{padding:10px 14px;font-size:12px}.journey-panel{grid-column:span 4;border-radius:16px;padding:20px 13px}.journey-panel .eyebrow{font-size:11px}.big-number{font-size:36px;margin-top:23px}.big-number span{font-size:18px}.journey-panel>p{font-size:11px}.topic-track{gap:2px;margin-top:20px}.progress-caption{font-size:11px;line-height:1.6;display:block}.journey-panel .journey-note{display:none}.curriculum{margin-top:28px}.section-heading{align-items:flex-start;margin-bottom:15px}.section-heading h2{font-size:17px}.section-heading p{font-size:11px;max-width:250px}.topic-count{font-size:11px;padding-top:3px}.topic-grid{gap:0}.topic-row{padding:17px 2px;gap:13px;min-height:100px}.topic-title{font-size:14px}.topic-description{font-size:12px}.topic-status{font-size:11px;margin-top:7px}.page-footer{font-size:11px;gap:8px}.page-footer .text-button{font-size:11px;white-space:nowrap}.lesson-heading{margin:28px 0 25px}.lesson-heading h1{font-size:36px}.lesson-heading p{font-size:12px}.study-progress{font-size:11px}.flashcard{padding:22px 19px;margin-top:19px;border-radius:17px}.flashcard h2{font-size:21px;margin-top:25px}.question-code{font-size:11px;line-height:1.85;padding:19px 15px;margin-top:22px}.flashcard-top{font-size:11px}.concept-symbol{font-size:65px}.reveal-area{flex-direction:column;gap:14px}.reveal-area .primary{width:100%}.answer h3{font-size:17px}.answer p{font-size:12px}.rating-buttons{gap:10px}.rating-buttons button{padding:12px;font-size:12px;gap:7px}kbd{display:none}.summary{margin:38px auto 0}.summary h1{font-size:39px}.summary>p:not(.eyebrow){font-size:12px}.session-stats span{font-size:25px}.session-stats small{font-size:11px}.storage-notice{left:12px;right:12px;bottom:12px;padding:12px;font-size:11px}.guide{padding:20px}.guide h2{font-size:17px}.guide ol{font-size:12px}}
@media(prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}