:root{--paper:#f7f8f3;--white:#fff;--ink:#1d352f;--muted:#6b7871;--green:#153e35;--lime:#d9f28e;--line:#e4e9e0;--orange:#ffcfb4;--red:#a33e34;--mono:'Cascadia Code','SFMono-Regular',Consolas,monospace;font-family:Inter,'Segoe UI',system-ui,sans-serif;color:var(--ink);background:var(--paper);font-synthesis:none}*{box-sizing:border-box}body{margin:0;font-size:15px;line-height:1.55}button,input,textarea,select{font:inherit}button,a,input,textarea,select{-webkit-tap-highlight-color:transparent}button{cursor:pointer}button:disabled{cursor:not-allowed}a{color:inherit}button:focus-visible,a:focus-visible,input:focus-visible,textarea:focus-visible,select:focus-visible{outline:3px solid #71a894;outline-offset:4px}button{color:inherit}h1,h2,h3,p{margin-top:0}h1,h2,h3{line-height:1.15;letter-spacing:-.035em}h1{font-size:38px}h2{font-size:24px}h3{font-size:19px}small{font-size:12px}.icon{width:20px;height:20px;fill:none;stroke:currentColor;stroke-width:1.7;stroke-linecap:round;stroke-linejoin:round;flex-shrink:0}.icon-library{position:absolute;width:0;height:0;overflow:hidden}.skip{position:absolute;left:16px;top:-70px;background:white;padding:12px;z-index:100}.skip:focus{top:10px}.initial-loading{padding:80px;text-align:center;color:var(--muted)}.brand{display:flex;align-items:center;gap:11px;font-size:19px;font-weight:750;letter-spacing:-.6px;text-decoration:none}.brand-mark{display:grid;place-items:center;width:40px;height:40px;border-radius:12px;background:var(--green);color:var(--lime);font-family:var(--mono);font-size:23px;font-weight:650;letter-spacing:-2px}.brand small{font-size:11px;color:var(--muted);font-weight:500;display:block;letter-spacing:1px;line-height:1.5}.btn{border:1px solid transparent;border-radius:10px;padding:12px 18px;font-weight:650;display:inline-flex;gap:10px;align-items:center;justify-content:center;text-decoration:none;transition:background .15s,transform .15s}.btn:hover{transform:translateY(-1px)}.btn:disabled{opacity:.6;transform:none}.primary{background:var(--green);color:white}.primary:hover{background:#24594a}.lime{background:var(--lime);color:var(--green)}.lime:hover{background:#cce77c}.secondary{background:white;border-color:var(--line)}.secondary:hover{background:#f2f6ed}.text-btn{border:0;background:none;padding:7px 0;color:var(--muted);display:inline-flex;gap:7px;align-items:center}.eyebrow{text-transform:uppercase;font-size:11px;font-weight:750;letter-spacing:1.6px;color:var(--muted);margin-bottom:14px}.muted{color:var(--muted)}.error{background:#fff0eb;color:var(--red);border-radius:9px;padding:11px 14px;margin:12px 0}.status-dot{width:7px;height:7px;border-radius:50%;background:#86b398;display:inline-block;margin-right:6px}.login{min-height:100vh;display:grid;grid-template-columns:1.05fr 1fr}.login-story{background:var(--green);color:#fff;padding:45px 11%;display:flex;flex-direction:column;justify-content:space-between;min-height:700px;overflow:hidden}.login-story .brand-mark{background:var(--lime);color:var(--green)}.login-story .brand small{color:#b5c5bd}.login-story h1{font-size:clamp(38px,4.4vw,65px);line-height:1.06;font-weight:600;margin:70px 0 22px;max-width:510px}.login-story h1 em{font-style:normal;color:var(--lime)}.login-story p{color:#c3d2c9;max-width:360px;font-size:16px}.code-postcard{background:#214b40;border:1px solid #426355;border-radius:15px;box-shadow:12px 15px 0 #10332b;padding:22px;margin:28px 0 35px;max-width:400px;transform:rotate(-2deg)}.window-dots{display:flex;gap:6px;margin-bottom:22px}.window-dots 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strong{color:var(--ink);font-weight:550}.login-mobile-brand{display:none}.layout{display:grid;grid-template-columns:228px 1fr;min-height:100vh}.sidebar{background:white;border-right:1px solid var(--line);padding:32px 23px;position:fixed;inset:0 auto 0 0;width:228px;display:flex;flex-direction:column;z-index:10}.sidebar .brand{margin-bottom:48px}.nav-label{font-size:10px;font-weight:700;color:#859085;letter-spacing:1.5px;margin:0 13px 12px}.nav{display:flex;flex-direction:column;gap:6px}.nav button{display:flex;align-items:center;gap:12px;border:0;border-radius:9px;background:none;padding:13px 14px;text-align:left;color:var(--muted);font-size:14px;font-weight:550}.nav button.active{background:#eaf2dd;color:var(--green);font-weight:700}.nav button:hover{background:#f1f5eb}.sidebar-tip{margin-top:auto;background:#f6f8ef;border:1px solid #e9eddf;border-radius:12px;padding:17px 16px;color:#64715f;font-size:12px;line-height:1.7}.sidebar-tip strong{display:block;color:var(--green);font-size:13px;margin:8px 0 6px}.sidebar-bottom{font-size:10px;color:#90998e;padding-top:22px;letter-spacing:.3px}.shell{grid-column:2;min-width:0}.topbar{height:84px;display:flex;align-items:center;justify-content:space-between;gap:14px;padding:0 42px;background:#ffffffa8;border-bottom:1px solid var(--line)}.breadcrumbs{font-size:13px;color:var(--muted)}.breadcrumbs span{color:var(--ink);margin-left:10px}.account{display:flex;align-items:center;gap:11px}.avatar{width:34px;height:34px;border-radius:50%;display:grid;place-items:center;background:#efe8d9;color:#715f3c;font-weight:650;text-transform:uppercase;font-size:12px}.account-name{font-size:12px;font-weight:600}.account-role{color:var(--muted);font-size:10px}.logout{border:0;background:none;padding:8px;color:#7a857c;display:flex}.main{padding:34px 42px 38px;max-width:1500px;margin:auto}.page-title{display:flex;align-items:flex-start;justify-content:space-between;gap:20px;margin:2px 0 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progress::-webkit-progress-bar{background:#edf1e7;border-radius:9px}.course-progress progress::-webkit-progress-value{background:#6b9459;border-radius:9px}.course-progress progress::-moz-progress-bar{background:#6b9459;border-radius:9px}.count{font-size:13px;font-weight:700;white-space:nowrap}.cards{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}.exercise-card{background:white;border:1px solid var(--line);border-radius:13px;padding:22px;display:flex;flex-direction:column;min-height:267px}.exercise-card.available{border-color:#91ac71;box-shadow:0 3px 0 #e5edda}.card-top{display:flex;align-items:center;justify-content:space-between;margin-bottom:23px}.exercise-number{display:grid;place-items:center;width:42px;height:42px;border-radius:12px;background:#eff4e7;color:#5c7b47;font-family:var(--mono);font-size:18px}.exercise-card:nth-child(2) .exercise-number{background:#fbefe4;color:#a67c54}.exercise-card:nth-child(3) .exercise-number{background:#eceef6;color:#7b80a0}.badge{display:inline-flex;align-items:center;gap:5px;font-size:10px;border-radius:15px;padding:5px 8px;background:#f0f2ed;color:#7d8679;white-space:nowrap}.badge .icon{width:12px;height:12px}.badge.available{background:#eaf2d8;color:#4d7134}.badge.passed{background:#e5f1e8;color:#3b7959}.exercise-card h3{font-size:17px;letter-spacing:-.4px;margin-bottom:9px}.exercise-card p{color:var(--muted);font-size:12px;line-height:1.6;margin-bottom:22px}.exercise-card .card-link{margin-top:auto;display:flex;align-items:center;justify-content:space-between;width:100%;padding:13px 0 0;background:none;border:0;border-top:1px solid #eef0e9;font-size:12px;font-weight:650;color:var(--green)}.exercise-card.locked .card-link{color:#90998c}.exercise-card.locked h3{color:#657260}.exercise-card .card-link .icon{width:17px;height:17px}.learning-note{display:flex;gap:12px;align-items:center;padding:18px 0;color:var(--muted);font-size:12px}.learning-note .icon{color:#8b9a75}.enrollment-select{padding:8px;border:1px solid var(--line);border-radius:8px;background:white;max-width:220px}.workspace-title{display:flex;align-items:center;gap:15px;margin:15px 0 24px}.workspace-title h1{font-size:25px;margin-bottom:6px}.workspace-title p{font-size:12px;color:var(--muted);margin:0}.workspace-grid{display:grid;grid-template-columns:minmax(240px,.8fr) minmax(360px,1.35fr);gap:23px;align-items:start}.statement{background:white;border:1px solid var(--line);border-radius:13px;padding:26px}.statement h2{font-size:18px;display:flex;gap:9px;align-items:center;margin-bottom:18px}.statement h3{font-size:12px;letter-spacing:0;margin:24px 0 8px}.statement p{font-size:13px;color:#5c6d60;line-height:1.8;white-space:pre-line}.example{border:1px solid var(--line);border-radius:9px;overflow:hidden;margin-top:12px}.example-head{background:#f5f7f0;padding:7px 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.icon{width:16px;color:var(--lime)}.language{font-family:var(--mono);color:#a5b8a6;font-size:10px}.code-area{position:relative;display:flex;min-height:330px;max-height:500px;padding-top:18px}.line-numbers{width:45px;text-align:right;flex-shrink:0;color:#627e6c;font-family:var(--mono);font-size:13px;line-height:23px;margin:0;padding:0 12px 18px 0;user-select:none;overflow:hidden;white-space:pre}.code-area textarea{resize:vertical;min-height:330px;width:100%;min-width:0;border:0;background:transparent;color:#e5f0de;line-height:23px;font-family:var(--mono);font-size:13px;padding:0 18px 18px 0;tab-size:4;white-space:pre;overflow:auto;outline-offset:-3px;caret-color:var(--lime)}.editor-foot{display:flex;justify-content:space-between;gap:10px;align-items:center;padding:11px 17px;color:#b0c1ad;font-size:10px;border-top:1px solid #29453a}.editor-foot .text-btn{font-size:10px;color:#c4d1bd}.editor-actions{display:flex;gap:10px;justify-content:flex-end;margin-top:15px}.editor-actions .btn{font-size:12px}.editor-actions .icon{width:16px;height:16px}.editor-caption{font-size:10px;color:var(--muted);text-align:right;margin-top:11px}.result{background:white;border:1px solid var(--line);border-radius:12px;padding:20px;margin-top:20px}.result h3{font-size:16px;display:flex;align-items:center;gap:9px;letter-spacing:-.25px;margin-bottom:9px}.result p{font-size:12px;color:var(--muted);margin-bottom:0}.result.pass{border-color:#a5c59c;background:#f5faef}.result.fail{border-color:#e8c0ab;background:#fff9f3}.result.error{border-color:#e7b9b1;background:#fff7f4;color:var(--ink)}.result.pending{border-color:#c5d2bd}.result .next{margin-top:16px;font-size:12px}.feedback-case{font-size:12px;border-top:1px solid var(--line);padding-top:12px;margin-top:13px}.feedback-case pre{max-height:160px;overflow:auto;background:#f0f3eb;padding:10px;border-radius:6px}.history-table{width:100%;border-collapse:collapse;text-align:left;font-size:12px;background:white}.table-wrap{border:1px solid var(--line);border-radius:12px;overflow:auto;background:white}.history-table th{background:#f0f3e9;padding:15px 19px;font-size:10px;color:var(--muted);font-weight:650;letter-spacing:.5px;white-space:nowrap}.history-table td{padding:16px 19px;border-top:1px solid var(--line)}.history-table .text-btn{font-size:12px;color:var(--green)}.history-table .badge{font-size:10px}.empty{padding:45px 25px;color:var(--muted);text-align:center;font-size:13px}.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;margin-bottom:25px}.stat{background:white;border:1px solid var(--line);border-radius:12px;padding:23px}.stat strong{display:block;font-size:30px;letter-spacing:-1px}.stat span{font-size:12px;color:var(--muted)}.activity-source{margin-top:18px;border-top:1px solid var(--line);padding-top:14px}.activity-source summary{font-size:12px;cursor:pointer}.activity-source pre{background:#f0f3eb;padding:15px;max-height:300px;overflow:auto}.spinner{display:inline-block;width:15px;height:15px;border:2px solid #b8c6ac;border-right-color:transparent;border-radius:50%;animation:spin .8s linear infinite;flex-shrink:0}@keyframes spin{to{transform:rotate(360deg)}}#toast{position:fixed;bottom:24px;left:50%;transform:translateX(-50%);background:var(--green);color:white;padding:12px 22px;box-shadow:0 5px 22px #12332330;border-radius:10px;font-size:12px;z-index:100;max-width:90vw}.main-footer{display:flex;justify-content:space-between;gap:15px;border-top:1px solid var(--line);font-size:10px;color:#88937f;padding-top:20px;margin-top:28px}.page-error{margin:30px 0}.refresh-row{display:flex;gap:10px;align-items:center}.refresh-row .btn{font-size:12px}.mobile-brand{display:none}.notice{font-size:12px;background:#edf3e4;border-radius:9px;padding:14px 16px;color:#4f6845;margin:18px 0}.footer-tag{font-family:var(--mono);color:#648454}
@media(min-width:1500px){.main{padding-top:45px}.hero{padding:40px}.hero h2{font-size:40px}.exercise-card{min-height:290px}}
@media(max-width:1150px){.layout{grid-template-columns:195px 1fr}.sidebar{width:195px;padding:28px 16px}.sidebar .brand{font-size:16px;gap:8px}.brand-mark{width:35px;height:35px;font-size:20px}.main{padding:28px}.topbar{padding:0 28px}.cards{gap:12px}.exercise-card{padding:18px}.badge{font-size:9px}.hero{grid-template-columns:1fr 170px;padding:28px}.hero-visual{transform:scale(.85)}.workspace-grid{grid-template-columns:1fr}.statement{order:0}.editor-column{order:1}.statement .examples{display:grid;grid-template-columns:1fr 1fr;gap:12px}.workspace-title h1{font-size:24px}}
@media(max-width:760px){h1{font-size:28px}.login{display:block}.login-story{display:none}.login-form-side{min-height:100vh;padding:35px 25px}.login-mobile-brand{display:flex;margin-bottom:45px}.layout{display:block}.sidebar{position:static;width:auto;display:block;padding:18px 20px;border-bottom:1px solid var(--line);border-right:0}.sidebar .brand{margin:0;font-size:18px}.sidebar .brand small{display:none}.nav-label,.sidebar-tip,.sidebar-bottom{display:none}.nav{flex-direction:row;margin-top:18px;gap:7px}.nav button{padding:9px 11px;font-size:12px;gap:7px}.nav .icon{width:16px}.topbar{height:64px;padding:0 20px}.breadcrumbs{font-size:11px}.account-name{font-size:11px}.account-role{display:none}.avatar{width:28px;height:28px;font-size:11px}.main{padding:25px 20px}.page-title{margin-bottom:23px}.page-title h1{font-size:25px}.page-title p{font-size:12px}.term{display:none}.hero{grid-template-columns:1fr;padding:25px;gap:0}.hero h2{font-size:30px}.hero-visual{display:none}.cards{grid-template-columns:1fr}.exercise-card{min-height:220px;padding:22px}.card-top{margin-bottom:18px}.course-progress{padding:15px;gap:10px;flex-wrap:wrap}.course-progress progress{width:100px}.course-progress .progress-copy{min-width:140px}.section-heading h2{font-size:19px}.section-heading>span{font-size:10px}.main-footer{flex-direction:column;gap:5px}.workspace-grid{display:block}.editor-column{margin-top:20px}.statement{padding:22px}.statement .examples{display:block}.workspace-title h1{font-size:22px}.workspace-title .exercise-number{display:none}.editor-actions .btn{flex:1;padding:12px}.editor-caption{text-align:left}.editor-foot{font-size:9px}.stats{gap:10px}.stat{padding:15px}.stat strong{font-size:25px}.stat span{font-size:10px}.history-table td,.history-table th{padding:13px}.refresh-row{align-items:flex-start;flex-direction:column}.enrollment-select{max-width:100%;width:100%;margin-bottom:10px}}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}
.course-filters{display:flex;gap:16px;margin:10px 0 24px}.course-filters label{display:flex;flex-direction:column;gap:7px;font-size:11px;font-weight:650;flex:1}.course-filters input,.course-filters select{padding:11px 13px;border:1px solid var(--line);border-radius:9px;background:white;color:var(--ink);width:100%}.chapter-group{margin-bottom:17px;border:1px solid var(--line);border-radius:13px;background:#fff}.chapter-group>summary{cursor:pointer;display:flex;justify-content:space-between;gap:12px;align-items:center;padding:19px 23px;list-style:none}.chapter-group>summary::-webkit-details-marker{display:none}.chapter-group summary small{display:block;font-size:9px;letter-spacing:1.4px;color:var(--muted);margin-bottom:5px}.chapter-group summary strong{font-size:17px;letter-spacing:-.4px}.chapter-count{font-size:11px;color:var(--muted);white-space:nowrap}.chapter-count span{margin-left:18px}.chapter-group .cards{padding:0 18px 20px}.chapter-group .exercise-card{min-height:245px;background:#fafbf7}.chapter-group .exercise-card.available{background:white}.exercise-hints{margin:20px 0;font-size:12px;color:#4f6a43}.exercise-hints summary{cursor:pointer;font-weight:650}.exercise-hints p{margin:10px 0 0}.attribution{font-size:10px!important;margin-top:24px;margin-bottom:0;color:var(--muted)}.attribution a{text-decoration-color:#bac6b2}.example-grid pre{max-height:250px;overflow:auto;white-space:pre-wrap}.rules{max-height:200px;overflow:auto}@media(max-width:760px){.course-filters{flex-direction:column;gap:12px}.chapter-group>summary{padding:17px}.chapter-group .cards{padding:0 12px 14px}.chapter-count{font-size:10px}}
.chapter-intro{white-space:pre-wrap;background:#f0f5e8;border-radius:9px;padding:17px 19px;margin:0 18px 19px;font-size:12px;line-height:1.9;color:#506547;max-width:900px}

.teacher-card{background:var(--white,#fff);border:1px solid #e0e6dc;border-radius:16px;padding:24px;margin:24px 0}.teacher-form{display:grid;gap:16px;max-width:720px}.teacher-form label{display:grid;gap:6px}.teacher-form small{color:#66756b}.teacher-form input[type=file]{max-width:100%}.teacher-form [hidden]{display:none}
/* Keep the insertion caret, without a rectangle around the code textarea. */
.code-area textarea:focus,.code-area textarea:focus-visible{outline:none}