:root{--paper:#fff;--ground:#fafbfc;--ink:#191e2b;--muted:#687082;--line:#dce1e8;--blue:#6655d7;--blue-deep:#5141ba;--accent:#267660;--ok:#267660;--error:#b03349;--amber:#845b12;--focus:#806cde;font-family:"Avenir Next",Avenir,"Segoe UI",Arial,sans-serif;font-synthesis:none;color-scheme:light}*{box-sizing:border-box}body{margin:0;background:var(--ground);color:var(--ink);font-size:16px;line-height:1.6}button,input,textarea,select{font:inherit}button{cursor:pointer}button:disabled{cursor:default;opacity:.35}button,a,input,select,textarea{touch-action:manipulation}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,textarea:focus-visible,summary:focus-visible{outline:3px solid var(--focus);outline-offset:3px}[hidden]{display:none!important}.skip{position:absolute;top:-100px;left:12px;z-index:10;padding:10px;background:white}.skip:focus{top:10px}.topbar{display:flex;justify-content:space-between;align-items:center;gap:20px;padding:18px max(24px,calc((100vw - 1000px)/2));background:white;border-bottom:1px solid var(--line)}.brand strong{font-size:17px;letter-spacing:-.3px}.brand small{display:block;color:var(--muted);font-size:12px}.language{display:flex;gap:3px;border:1px solid var(--line);border-radius:24px;padding:3px}.language button{border:0;border-radius:20px;padding:8px 12px;font-size:13px;background:transparent;color:var(--muted)}.language button[aria-pressed=true]{background:#edeafb;color:#4533a2;font-weight:600}.main{max-width:1000px;padding:25px 24px 40px;margin:auto}.study-nav{display:flex;justify-content:space-between;align-items:center;gap:20px;margin-bottom:22px}.browse-button{display:flex;align-items:center;gap:10px;background:white;border:1px solid var(--line);border-radius:9px;padding:10px 15px;min-height:44px;color:var(--ink);font-size:14px;font-weight:600}.browse-button:hover{border-color:var(--blue)}.progress-area{font-size:12px;color:var(--muted);min-width:160px;max-width:50%;text-align:right}.progress-track{height:4px;background:#e6e8ed;border-radius:4px;overflow:hidden;margin-top:6px}.progress-fill{height:100%;background:var(--accent)}.worksheet{background:white;border:1px solid var(--line);border-radius:12px;overflow:hidden}.worksheet:focus{outline:none}.exercise-heading{padding:25px 30px 20px}.heading-line{display:flex;gap:20px;align-items:center;justify-content:space-between;color:var(--muted);font-size:12px;margin-bottom:10px}.save-indicator{font-size:11px;color:var(--muted)}.save-indicator::before{content:'✓';color:var(--accent);margin-right:5px}.exercise-heading h1{font-size:28px;line-height:1.25;letter-spacing:-.7px;margin:0 0 12px;font-weight:650}.prompt{font-size:16px;max-width:78ch;margin:0}.optional-note{font-size:12px;color:var(--blue);margin:12px 0 0}.exercise-body{padding:0 30px 25px}.bilingual{display:grid;grid-template-columns:1fr 1fr;gap:24px}.bilingual>[lang]{display:block}.bilingual>[lang=en]{border-left:1px solid var(--line);padding-left:24px}.part-tabs{display:flex;flex-wrap:wrap;gap:7px;padding:15px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}.part-tabs button{min-height:39px;border:1px solid transparent;border-radius:7px;background:transparent;color:var(--muted);padding:7px 12px;font-size:13px}.part-tabs button:hover{background:#f6f4fe}.part-tabs button[aria-current=step]{background:#edeafb;color:#4533a2;border-color:#e1dbfc;font-weight:600}.task-tick{margin-left:8px;color:var(--accent)}.part-tabs .bilingual{display:flex;gap:6px}.part-tabs .bilingual>[lang=en]{border:0;padding:0}.part-tabs .bilingual>[lang=en]::before{content:'/ ';color:var(--muted)}.part{padding:22px 0 16px}.part h2{font-size:18px;font-weight:600;line-height:1.5;margin:0 0 18px}.data-set{display:flex;flex-wrap:wrap;gap:5px;margin:4px 0 20px;padding:12px 15px;background:#f6f7fa;border-radius:8px;font-variant-numeric:tabular-nums}.datum{padding:2px 8px;min-width:26px;text-align:center}.table-wrap{overflow-x:auto;max-width:100%;margin:16px 0;overscroll-behavior-x:contain}table{width:100%;border-collapse:collapse;font-variant-numeric:tabular-nums;font-size:14px}caption{text-align:left;font-size:12px;color:var(--muted);padding-bottom:8px}th{font-weight:600;text-align:left;padding:11px 12px;background:#f4f5f8;border-bottom:1px solid var(--line);font-size:13px}td{padding:9px 12px;border-bottom:1px solid #edf0f4;vertical-align:top}tbody th{background:white;font-size:14px;font-weight:500;border-bottom:1px solid #edf0f4}th .bilingual,td .bilingual{display:block}th .bilingual>[lang=en],td .bilingual>[lang=en]{border:0;padding:0;margin-top:3px;font-size:11px;color:var(--muted)}.fixed-value{display:flex;align-items:center;min-height:39px;white-space:nowrap}.field{max-width:310px}.fields{display:flex;gap:18px;flex-wrap:wrap}.field label{display:block;font-weight:500;font-size:14px;margin-bottom:6px}.number-input,select{width:100%;min-width:90px;min-height:42px;border:1px solid #bcc3ce;background:white;color:var(--ink);border-radius:6px;padding:7px 10px;font-variant-numeric:tabular-nums}.number-input:focus,select:focus{border-color:var(--blue)}td .field{min-width:96px}td .number-input{max-width:150px}.precision{display:block;color:var(--muted);font-size:10px;line-height:1.4;margin-top:4px;max-width:170px}.field-status{display:block;font-size:12px;font-weight:600;margin-top:4px;line-height:1.4}.field-status:empty{display:none}.field-status.correct{color:var(--ok)}.field-status.incorrect{color:var(--error)}.field-status.unanswered{color:var(--muted)}.field[data-result=correct] .number-input,.field[data-result=correct] select{border-color:#6eab97;background:#f8fcfa}.field[data-result=incorrect] .number-input,.field[data-result=incorrect] select{border-color:#c57080;background:#fffafb}.controls{display:flex;gap:10px;flex-wrap:wrap;align-items:center;margin-top:21px}.button{min-height:44px;border:1px solid var(--line);border-radius:8px;padding:10px 17px;background:white;color:var(--ink);font-size:14px;font-weight:600}.button.primary{background:var(--blue);color:white;border-color:var(--blue)}.button.primary:hover{background:var(--blue-deep)}.button.secondary:hover{background:#f5f6f9}.viewed-note{font-size:11px;color:var(--amber)}.check-summary{font-size:12px;color:var(--muted);margin-top:10px}.check-summary:empty{display:none}.solution{margin-top:20px;padding:18px 20px;background:#f0f8f4;border:1px solid #cde5d8;border-radius:8px}.solution h3{margin:0 0 9px;font-size:14px;color:var(--accent)}.solution p{margin:0;font-size:15px}.solution table th{background:#e6f2eb}.solution dl{font-size:14px}.solution dd{font-weight:600;margin:4px 0 14px}.entry-help{font-size:12px;color:var(--muted);margin:8px 0 20px}.entry-help summary,.working-section summary,.source-details summary{cursor:pointer}.entry-help p{margin:9px 0}.working-section{border-top:1px solid var(--line);padding-top:18px;font-size:14px}.working-section summary{font-weight:500}.working-section p,.self-review-note{font-size:12px;color:var(--muted);margin:10px 0}.working-input{width:100%;min-height:150px;resize:vertical;border:1px solid #bcc3ce;border-radius:7px;padding:12px;background:white;color:var(--ink);line-height:1.6}.written-input{min-height:130px}.bottom-nav{display:flex;justify-content:space-between;align-items:center;gap:15px;margin-top:18px}.task-position{font-size:12px;color:var(--muted)}.footer{font-size:12px;color:var(--muted);text-align:center;margin-top:25px}.footer-note{font-size:11px;margin-top:8px}.footer .source-details{text-align:center;margin-top:10px}.source-details{font-size:12px;color:var(--muted);margin:15px 0}.note{background:#f6f7fa;padding:12px 14px;border-radius:7px;font-size:12px;color:var(--muted);margin:0 0 20px}.warning{padding:13px 18px;background:#fff7e5;border:1px solid #eadbb9;border-radius:8px;color:var(--amber);margin-bottom:20px;font-size:13px}.graph-editor{display:grid;grid-template-columns:minmax(0,1fr) 250px;gap:16px;align-items:start}.graph-inputs{max-height:410px;overflow:auto;border:1px solid var(--line);border-radius:8px}.graph-inputs th{position:sticky;top:0;z-index:1}.graph-inputs td{padding:8px}.graph-inputs .number-input{min-width:65px;width:85px}.graph-panel{overflow-x:auto;min-width:0;border:1px solid var(--line);border-radius:8px;padding:12px 6px;background:#fdfdfe}.graph-panel h3{font-size:12px;font-weight:500;color:var(--muted);margin:0 10px 5px}.chart{width:100%;min-width:470px;height:auto;display:block}.chart text{font-family:inherit;font-size:13px;fill:var(--muted)}.chart .axis{stroke:#a2aab8}.chart .gridline{stroke:#e8ebf0}.chart-legend{display:flex;gap:14px;justify-content:center;flex-wrap:wrap;font-size:12px}.chart-legend i{width:10px;height:10px;display:inline-block;border-radius:2px;margin-right:5px}.chart-empty{font-size:12px;text-align:center;color:var(--muted);margin:8px}.choice-list{border:0;margin:0;padding:0;display:grid;gap:8px}.choice-list label{display:flex;gap:10px;align-items:flex-start;border:1px solid var(--line);border-radius:7px;padding:11px 14px;font-weight:400;cursor:pointer;margin:0}.choice-list input,.review-label input{width:18px;height:18px;flex-shrink:0;accent-color:var(--blue);margin:3px 0 0}.field:has(.choice-list){max-width:none}.review-label{display:flex;gap:10px;font-size:12px;margin-top:14px}.screen-reader{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.loading{padding:10vw}
dialog{border:1px solid var(--line);border-radius:14px;padding:24px;width:min(620px,calc(100% - 28px));max-height:80vh;color:var(--ink);box-shadow:0 20px 80px #191e2b26}dialog::backdrop{background:#191e2b5c}dialog header{display:flex;align-items:center;justify-content:space-between;gap:15px}dialog h2{font-size:20px;margin:0 0 16px}.icon-button{border:0;background:#f3f4f7;border-radius:50%;width:36px;height:36px;font-size:24px;line-height:1}input[type=search]{width:100%;padding:10px 12px;border:1px solid #bcc3ce;border-radius:8px;min-height:44px;font-size:14px}.picker-groups{margin-top:20px}.topic{margin-top:22px}.topic:first-child{margin-top:0}.topic h3{font-size:13px;font-weight:500;color:var(--muted);margin:0 0 9px}.exercise-grid{display:grid;grid-template-columns:repeat(8,minmax(0,1fr));gap:7px}.exercise-link{position:relative;min-height:42px;border:1px solid var(--line);border-radius:7px;background:white;color:var(--ink);font-size:14px}.exercise-link:hover{border-color:var(--blue);background:#f7f5ff}.exercise-link[aria-current=page]{border-color:var(--blue);background:#edeafb;color:#4533a2;font-weight:600}.dot{position:absolute;right:5px;bottom:5px;width:6px;height:6px;border-radius:50%}.dot.independent{background:var(--accent)}.dot.helped,.dot.viewed{background:#c89435}.dot.attempted{background:#adb3bf}.dot.unavailable{background:#c57080}.exercise-link:has(.dot.unavailable){border-style:dashed}#exercise-picker .bilingual{gap:12px}#exercise-picker .bilingual>[lang=en]{padding-left:12px}.fixed-value>.bilingual{width:100%}
@media(max-width:850px){.graph-editor{grid-template-columns:1fr}.graph-inputs{max-height:300px}.graph-inputs .number-input{width:100%}}
@media(max-width:600px){.topbar{padding:14px 16px;gap:10px;flex-wrap:wrap}.brand small{font-size:11px}.brand strong{font-size:15px}.language{margin-left:auto}.language button{font-size:12px;padding:7px 9px}.main{padding:18px 12px 30px}.study-nav{gap:12px;margin-bottom:16px}.progress-area{min-width:100px;font-size:10px}.browse-button{padding:9px 11px;font-size:12px}.exercise-heading{padding:21px 20px 17px}.exercise-body{padding:0 20px 22px}.exercise-heading h1{font-size:26px}.heading-line{font-size:11px;align-items:flex-start}.save-indicator{display:none}.bilingual{grid-template-columns:1fr;gap:9px}.bilingual>[lang=en]{border-left:0;border-top:1px solid var(--line);padding-left:0;padding-top:9px}.part{padding:20px 0 14px}.part h2{font-size:17px}.part-tabs button{padding:6px 10px;font-size:12px}.fields{display:grid;grid-template-columns:1fr;gap:14px}.field{max-width:none}.number-input,select{font-size:16px}.precision{font-size:10px}.button{padding:9px 13px;font-size:13px}.task-position{font-size:11px}.prompt{font-size:15px}.exercise-grid{grid-template-columns:repeat(6,minmax(0,1fr))}dialog{padding:20px}.brand .bilingual{display:none}.progress-area .bilingual{display:block}.progress-area .bilingual>[lang=en]{padding:0;border:0}.study-nav .bilingual{display:block}.study-nav .bilingual>[lang=en]{padding:0;border:0}.graph-inputs .number-input{font-size:16px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important}}