:root{color-scheme:light;--bg:#f5f4ef;--surface:#fffefa;--ink:#182238;--muted:#606978;--line:#dadcd9;--accent:#315acb;--accent-soft:#edf1ff;--good:#167049;--good-bg:#eaf6ee;--bad:#ad3541;--bad-bg:#fff0f1;--shadow:0 12px 40px #1c2b4310;--curve:cubic-bezier(.22,.68,0,1)}
:root[data-theme=dark]{color-scheme:dark;--bg:#141b26;--surface:#1b2432;--ink:#edf0f7;--muted:#acb7c9;--line:#354254;--accent:#a2b9ff;--accent-soft:#26344f;--good:#91d8b2;--good-bg:#203a30;--bad:#ffb0b8;--bad-bg:#432c35;--shadow:0 12px 40px #0002}
*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font-family:"Segoe UI",Tahoma,Arial,sans-serif;font-size:1rem;line-height:1.6}button,input,select{font:inherit}button,a,input,select{ -webkit-tap-highlight-color:transparent}button{cursor:pointer}button:disabled{cursor:default;opacity:.5}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid var(--accent);outline-offset:4px}a{color:var(--accent)}h1,h2,h3,p{margin-top:0}h1{font-size:clamp(2.2rem,4.3vw,3.5rem);letter-spacing:-.055em;line-height:1.12;font-weight:650;margin-bottom:24px}h2{font-size:1.55rem;letter-spacing:-.035em;line-height:1.25}h3{font-size:1.1rem;line-height:1.45}p{margin-bottom:16px}.header{max-width:1200px;margin:auto;padding:32px 40px;display:flex;justify-content:space-between;align-items:center}.brand{display:flex;align-items:center;gap:12px;font-size:1.25rem;font-weight:650;letter-spacing:-.04em;color:var(--ink);text-decoration:none}.brand-mark{display:grid;place-items:center;width:36px;height:36px;border:1px solid var(--accent);border-radius:10px;color:var(--accent);font-size:1.8125rem;font-weight:400}.brand-number{margin-left:4px;font-weight:400}.brand-caption{font-size:0.6875rem;letter-spacing:.16em;color:var(--muted);margin-left:15px;padding-left:24px;border-left:1px solid var(--line)}.theme-toggle{border:1px solid var(--line);background:var(--surface);color:var(--ink);border-radius:25px;padding:8px 12px;display:flex;gap:9px;align-items:center;font-size:1.1875rem}.theme-track{width:29px;height:16px;border-radius:10px;background:var(--line);padding:3px}.theme-track span{display:block;width:10px;height:10px;border-radius:50%;background:var(--ink);transition:transform .24s var(--curve)}[data-theme=dark] .theme-track span{transform:translateX(13px)}.shell{max-width:1120px;margin:0 auto;padding:0 40px}.tabs{display:flex;gap:28px;border-bottom:1px solid var(--line);margin-bottom:52px}.tabs button{position:relative;background:none;border:0;color:var(--muted);padding:15px 0;font-weight:550;transition:color .2s}.tabs button.active{color:var(--ink)}.tabs button.active:after{content:"";position:absolute;bottom:-1px;left:0;right:0;height:3px;border-radius:3px;background:var(--accent)}.tabs span{font-size:0.875rem;margin-left:5px}main{min-height:570px;outline:none}.setup{display:grid;grid-template-columns:1fr 1.08fr;gap:64px;align-items:start;padding:18px 0 42px}.eyebrow{font-size:0.75rem;letter-spacing:.14em;text-transform:uppercase;color:var(--accent);font-weight:650;margin-bottom:20px}.intro{padding-top:12px}.intro>p{color:var(--muted);max-width:390px;font-size:1.0625rem}.stats{display:flex;gap:35px;margin:36px 0}.stats strong{display:block;font-size:1.8125rem;line-height:1.35;font-weight:550;letter-spacing:-.04em}.stats span{font-size:0.8125rem;color:var(--muted)}.mini-note{padding:20px 0;border-top:1px solid var(--line);font-size:0.875rem;color:var(--muted);max-width:380px}.mini-note strong{display:block;font-weight:550;color:var(--ink);margin-bottom:4px}.panel{background:var(--surface);border:1px solid var(--line);border-radius:22px;padding:32px;box-shadow:var(--shadow)}.panel-title{display:flex;justify-content:space-between;align-items:center;margin-bottom:28px}.panel-title h2{margin:0}.small-count{font-size:0.75rem;border:1px solid var(--line);padding:4px 10px;border-radius:20px;color:var(--muted)}label.field-label{display:block;font-size:0.875rem;font-weight:550;margin-bottom:10px}.field{margin-bottom:25px}select,input[type=text]{width:100%;padding:13px 14px;border:1px solid var(--line);border-radius:10px;background:var(--bg);color:var(--ink)}.type-picker{display:grid;grid-template-columns:repeat(4,1fr);gap:7px}.type-picker button{background:var(--bg);color:var(--muted);border:1px solid var(--line);border-radius:9px;padding:10px 4px;font-size:0.875rem}.type-picker button[aria-pressed=true]{background:var(--accent-soft);color:var(--accent);border-color:var(--accent)}.button{border:1px solid var(--accent);background:var(--accent);color:#fff;border-radius:10px;padding:12px 21px;font-weight:600;min-height:48px;transition:transform .2s var(--curve),filter .2s}.button:hover{filter:brightness(1.08);transform:translateY(-1px)}[data-theme=dark] .button{color:#122041}.button.secondary{background:transparent;color:var(--ink);border-color:var(--line)}.button.quiet{background:transparent;border-color:transparent;color:var(--accent);box-shadow:none;padding-left:0}.wide{width:100%}.subtle{font-size:0.8125rem;color:var(--muted);margin:14px 0 0}.check-row{display:flex;gap:12px;align-items:center;cursor:pointer;font-size:0.9375rem}.check-row input{width:18px;height:18px;accent-color:var(--accent)}.exam-facts{list-style:none;padding:0;margin:0 0 30px}.exam-facts li{display:flex;justify-content:space-between;padding:12px 0;border-bottom:1px solid var(--line);color:var(--muted);font-size:0.9375rem}.exam-facts strong{color:var(--ink);font-weight:550}.actions{display:flex;gap:12px;align-items:center;justify-content:flex-end;flex-wrap:wrap;margin-top:24px}.quiz-wrap{max-width:820px;margin:auto}.session-top{display:flex;justify-content:space-between;gap:16px;align-items:center;margin-bottom:15px;font-size:0.875rem;color:var(--muted)}.progress{height:4px;border-radius:4px;background:var(--line);overflow:hidden;margin-bottom:28px}.progress span{display:block;height:100%;background:var(--accent);transition:width .4s var(--curve)}.question-panel{min-height:410px;padding:38px}.question-meta{display:flex;gap:12px;align-items:center;margin-bottom:20px;font-size:0.75rem;color:var(--muted);letter-spacing:.03em}.question-meta .badge{color:var(--accent);background:var(--accent-soft);padding:4px 9px;border-radius:5px}.question-prompt{font-size:clamp(1.22rem,2.5vw,1.5rem);font-weight:550;letter-spacing:-.025em;line-height:1.5;margin-bottom:25px;white-space:pre-line}.options{display:grid;gap:10px;border:0;padding:0;margin:0;min-width:0}.option{display:flex;gap:14px;align-items:center;padding:14px 16px;border:1px solid var(--line);border-radius:11px;background:var(--bg);cursor:pointer;transition:background .2s,border-color .2s}.option:has(input:checked){border-color:var(--accent);background:var(--accent-soft)}.option input{accent-color:var(--accent);width:17px;height:17px;flex-shrink:0}.option-letter{font-size:0.75rem;color:var(--muted)}.option.correct{border-color:var(--good);background:var(--good-bg)}.option.wrong{border-color:var(--bad);background:var(--bad-bg)}.feedback{display:grid;grid-template-rows:0fr;transition:grid-template-rows .32s var(--curve),opacity .32s;opacity:0}.feedback.open{grid-template-rows:1fr;opacity:1}.feedback-inner{overflow:hidden;min-height:0}.feedback-content{padding-top:25px}.feedback-status{font-size:0.9375rem;font-weight:650;color:var(--good)}.feedback-status.wrong{color:var(--bad)}.answer-line{font-size:0.9375rem;margin-top:8px}.explanation{font-size:0.9375rem;color:var(--muted);line-height:1.8;white-space:pre-line}.language-switch{display:inline-flex;gap:3px;border:1px solid var(--line);border-radius:8px;padding:3px;margin:8px 0 14px}.language-switch button{background:transparent;color:var(--muted);border:0;border-radius:5px;padding:5px 12px;font-size:0.875rem}.language-switch button[aria-pressed=true]{background:var(--accent-soft);color:var(--accent)}.source{font-size:0.75rem;color:var(--muted);padding-top:16px;border-top:1px solid var(--line);line-height:1.65}.source>span{display:block}.link-button{border:0;background:none;color:var(--accent);padding:0;text-align:left;text-decoration:underline;text-underline-offset:4px;font-size:0.875rem}.quiz-nav{display:flex;align-items:center;justify-content:space-between;margin-top:20px;gap:12px}.question-grid{display:flex;flex-wrap:wrap;gap:7px;margin-top:28px}.question-grid button{width:35px;height:35px;border-radius:7px;background:var(--surface);border:1px solid var(--line);color:var(--muted);font-size:0.8125rem}.question-grid button.answered{background:var(--accent-soft);color:var(--accent)}.question-grid button.current{border:2px solid var(--accent);color:var(--ink)}.error{color:var(--bad);font-size:0.875rem;min-height:22px;margin-top:8px}.timer{font-variant-numeric:tabular-nums;color:var(--ink);white-space:nowrap}.timer.low{color:var(--bad)}.text-muted{color:var(--muted)}.study-heading{display:flex;justify-content:space-between;gap:20px;align-items:start;margin-bottom:28px}.study-heading h1{font-size:2.8rem;margin-bottom:10px}.study-layout{display:grid;grid-template-columns:235px minmax(0,1fr);gap:32px;align-items:start}.study-sidebar{position:sticky;top:24px}.topic-button{width:100%;display:flex;justify-content:space-between;gap:10px;text-align:left;border:0;border-left:2px solid transparent;background:none;padding:11px 14px;color:var(--muted);font-size:0.875rem;border-radius:0 8px 8px 0}.topic-button.active{background:var(--accent-soft);color:var(--accent);border-left-color:var(--accent)}.concept-list{display:flex;flex-direction:column;gap:12px}.concept-card{background:var(--surface);border:1px solid var(--line);border-radius:13px;overflow:hidden;transition:border-color .2s}.concept-card.active{border-color:var(--accent)}.concept-trigger{display:flex;align-items:center;justify-content:space-between;gap:20px;width:100%;background:transparent;border:0;text-align:left;color:var(--ink);padding:19px 22px;font-weight:550;font-size:1rem}.concept-trigger span:last-child{color:var(--accent);font-size:1.375rem;transition:transform .3s}.concept-card.active .concept-trigger span:last-child{transform:rotate(45deg)}.concept-body{display:grid;grid-template-rows:0fr;opacity:0;transition:grid-template-rows .35s var(--curve),opacity .3s}.concept-card.active .concept-body{grid-template-rows:1fr;opacity:1}.concept-inner{overflow:hidden;min-height:0}.concept-content{padding:0 22px 24px}.concept-content p{font-size:1rem;color:var(--muted);white-space:pre-line;line-height:1.85}.concept-content ul{padding-inline-start:23px;color:var(--muted)}.concept-content li{margin-bottom:7px}.formula{background:var(--bg);border-left:3px solid var(--accent);border-radius:0 8px 8px 0;padding:16px;font-family:Consolas,"Courier New",monospace;white-space:pre-line;font-size:0.875rem;line-height:1.9;margin:20px 0;overflow-wrap:anywhere;direction:ltr;text-align:left}.study-label{font-size:0.8125rem;font-weight:650;color:var(--ink);margin-bottom:8px}.table-scroll{max-width:100%;overflow-x:auto;border:1px solid var(--line);border-radius:10px;margin:15px 0 22px}table{border-collapse:collapse;width:100%;font-size:0.875rem;line-height:1.65}th,td{text-align:start;padding:13px 14px;border-bottom:1px solid var(--line);vertical-align:top;overflow-wrap:anywhere}th{background:var(--accent-soft);color:var(--ink);font-weight:600}td{color:var(--muted)}tr:last-child td{border-bottom:0}caption{text-align:start;font-weight:600;padding:12px 14px;background:var(--bg);color:var(--ink)}.result-top{display:grid;grid-template-columns:180px 1fr;gap:35px;align-items:center;margin-bottom:32px}.score-ring{--score:0%;width:165px;height:165px;border-radius:50%;background:conic-gradient(var(--accent) var(--score),var(--line) 0);padding:7px}.score-ring>div{background:var(--surface);border-radius:50%;height:100%;display:flex;flex-direction:column;align-items:center;justify-content:center}.score-ring strong{font-size:2.5rem;letter-spacing:-.06em;font-weight:550;line-height:1.3}.score-ring span{font-size:0.8125rem;color:var(--muted)}.result-top h1{font-size:2.5rem;margin-bottom:12px}.review-item{border-top:1px solid var(--line);padding:20px 0}.review-item summary{cursor:pointer;list-style:none;display:flex;gap:15px;align-items:start;font-size:0.9375rem}.review-item summary::-webkit-details-marker{display:none}.review-status{color:var(--good);font-weight:600;min-width:68px;font-size:0.8125rem}.review-status.wrong{color:var(--bad)}.review-content{padding:20px 0 0 83px}.back-link{margin-bottom:22px}.view-enter{animation:enter .35s var(--curve) both}@keyframes enter{from{opacity:0;transform:translateY(7px)}to{opacity:1;transform:translateY(0)}}footer{display:flex;justify-content:space-between;gap:20px;border-top:1px solid var(--line);padding:24px 0;margin-top:55px;font-size:0.75rem;color:var(--muted)}.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}dialog{max-width:440px;width:calc(100% - 36px);padding:28px;background:var(--surface);color:var(--ink);border:1px solid var(--line);border-radius:18px;box-shadow:var(--shadow)}dialog::backdrop{background:#08142999}.noscript{margin:40px}input:disabled{opacity:1}bdi{unicode-bidi:isolate}[dir=rtl]{font-family:Tahoma,"Segoe UI",Arial,sans-serif;letter-spacing:normal}[dir=rtl] h2,[dir=rtl] h3{letter-spacing:normal}
body,.panel,.concept-card,.option,select,input[type=text],.theme-toggle{transition:background-color .25s var(--curve),color .25s var(--curve),border-color .25s var(--curve)}.table-scroll th bdi,.table-scroll td bdi{unicode-bidi:isolate}.concept-card{scroll-margin-top:20px}.header,.tabs,.stats,.panel-title,.question-meta,.quiz-nav{flex-wrap:wrap}.header{gap:16px}.panel-title{gap:12px}.topic-button span{min-width:0;overflow-wrap:anywhere}.setup{grid-template-columns:minmax(0,1fr) minmax(0,1.08fr)}.skip-link{position:absolute;top:5px;left:20px;z-index:5;transform:translateY(-150%);padding:8px 15px;border-radius:8px;background:var(--surface)}.skip-link:focus{transform:none}
@media(max-width:800px){.header{padding:24px}.shell{padding:0 24px}.brand-caption{display:none}.tabs{margin-bottom:30px;gap:25px}.setup{gap:30px;grid-template-columns:1fr}.intro{max-width:600px}.intro>p{max-width:540px}.stats{margin:25px 0}.mini-note{display:none}.panel{padding:25px}.study-layout{grid-template-columns:1fr;gap:22px}.study-sidebar{position:static;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:5px}.study-heading h1{font-size:2.2rem}.question-panel{padding:25px}.result-top{gap:22px;grid-template-columns:130px 1fr}.score-ring{width:125px;height:125px}.score-ring strong{font-size:2rem}.result-top h1{font-size:2rem}.review-content{padding-left:0}}
@media(max-width:450px){.header{padding:20px}.shell{padding:0 20px}.tabs{gap:24px;font-size:0.875rem}.panel{border-radius:16px;padding:23px}.setup{padding-top:0}.stats{gap:25px}.study-heading{flex-direction:column;gap:0}.topic-button{font-size:0.8125rem;padding:9px}.concept-trigger{padding:16px}.concept-content{padding:0 16px 20px}.question-panel{padding:22px}.question-meta{gap:8px;font-size:0.6875rem}.question-prompt{font-size:1.15rem}.option{padding:13px 12px;gap:9px}.result-top{grid-template-columns:1fr}.result-top h1{font-size:2rem}footer{flex-direction:column;gap:6px}.quiz-nav .button{font-size:0.875rem;padding:11px 14px}.source{font-size:0.75rem}}
.topic-button span:last-child{white-space:nowrap;min-width:1.5em;flex-shrink:0;text-align:right}.mobile-topic{display:none}
@media(max-width:800px){.mobile-topic{display:block}.study-sidebar{display:none}}
@media(max-width:450px){.type-picker{grid-template-columns:repeat(2,minmax(0,1fr))}.table-scroll:has(th:nth-child(4)) table{min-width:580px}.table-scroll:has(th:nth-child(4)) th[scope=row]{min-width:110px}.table-scroll:has(th:nth-child(4)):before{content:"Swipe or scroll to compare";display:block;padding:8px 14px;font-size:.75rem;color:var(--muted);background:var(--bg);direction:ltr;text-align:left}}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}
.tabs{flex-wrap:nowrap;overflow-x:auto;gap:28px;padding:0 5px;scrollbar-width:thin}.tabs button{flex-shrink:0;white-space:nowrap}.tabs:focus-within{overflow:visible;overflow-x:auto}.topic-picker{border:0;padding:0;margin:0;min-width:0}.topic-picker legend{font-size:.875rem;font-weight:600;padding:0}.topic-actions{display:flex;gap:20px;margin:8px 0 14px}.topic-choice{display:flex;gap:12px;align-items:center;padding:11px 0;border-bottom:1px solid var(--line);cursor:pointer;font-size:.875rem;line-height:1.45}.topic-choice>span:nth-child(2){flex:1;min-width:0}.topic-choice input{accent-color:var(--accent);width:18px;height:18px;flex-shrink:0}.topic-choice .topic-count{color:var(--muted);font-variant-numeric:tabular-nums;min-width:24px;text-align:right}.scope-badge{display:inline-block;font-size:.6875rem;line-height:1.4;font-weight:500;letter-spacing:0;padding:4px 7px;border:1px dashed var(--accent);border-radius:6px;color:var(--accent);background:var(--accent-soft);vertical-align:middle;margin:4px 0}.topic-choice .scope-badge,.topic-button .scope-badge{display:block;width:fit-content}.scope-note{margin:16px 0 23px}.selection-status{font-size:.8125rem;color:var(--muted);min-height:26px;margin:20px 0 10px}.blank-hint{margin:-12px 0 16px}.memory-cue{padding:16px 18px;background:var(--accent-soft);border-radius:10px;margin:18px 0}.memory-cue strong{color:var(--accent);font-size:.8125rem}.memory-cue p{margin:4px 0 0;color:var(--ink)}.simple-definition{font-weight:550;color:var(--ink)!important}.formula-links{display:flex;flex-direction:column;align-items:flex-start;gap:12px;margin:12px 0 24px}.filter-row{display:flex;gap:15px;align-items:center;max-width:580px}.filter-row label{font-weight:550}.calculation-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px;margin:30px 0}.formula-card{padding:25px;scroll-margin-top:20px;min-width:0;box-shadow:none}.formula-card h3{margin-bottom:12px;font-size:1.125rem}.formula-card h4{font-size:.8125rem;color:var(--ink);margin:20px 0 8px}.formula-card p{font-size:.9375rem;line-height:1.8;color:var(--muted)}.formula-card .formula{margin:14px 0;font-size:.8125rem}.formula-card .calculation-answer{display:inline-block;color:var(--good);background:var(--good-bg);border-radius:6px;padding:5px 10px;font-family:Consolas,monospace;margin:0}.formula-card .source{margin-top:20px}.formula-card ul{font-size:.9375rem;line-height:1.8;color:var(--muted);padding-inline-start:22px}.formula-card[dir=rtl] .link-button{text-align:right}.review-jumps{display:flex;flex-wrap:wrap;gap:8px;padding:20px 0;border-block:1px solid var(--line)}.review-jumps a{display:block;border:1px solid var(--line);border-radius:20px;padding:6px 12px;font-size:.75rem;text-decoration:none;background:var(--surface)}.quick-topic{padding-top:40px;scroll-margin-top:15px}.section-heading{display:flex;gap:15px;align-items:center;flex-wrap:wrap;margin-bottom:20px}.section-heading h2{margin:0}.takeaways{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px}.takeaway{padding:20px;background:var(--surface);border:1px solid var(--line);border-radius:12px}.takeaway h3{font-size:1rem;margin-bottom:10px}.takeaway p{font-size:.875rem;color:var(--muted);margin-bottom:10px;line-height:1.8}.takeaway .memory-line{color:var(--accent)}.comparison-review{padding:17px 0;border-bottom:1px solid var(--line);font-size:.875rem}.comparison-review summary{cursor:pointer;color:var(--accent);font-weight:550}.quick-question-heading{margin:25px 0 16px}.quick-question{padding:20px 22px;background:var(--surface);border-left:3px solid var(--accent);border-radius:0 10px 10px 0;margin:12px 0}.quick-question p{font-size:.875rem;line-height:1.8;margin-bottom:10px}.quick-question p[dir=rtl]{color:var(--muted)}.quick-answer{color:var(--good)}.quick-question .source{margin-top:15px}.compact .formula-card{padding:22px}.compact .variable-text{font-size:.8125rem}.optional-heading{margin-top:35px}.quick-example{margin-bottom:10px}.question-meta .scope-badge{letter-spacing:0}
@media(max-width:800px){.calculation-grid{grid-template-columns:1fr}.tabs{gap:24px}.setup{gap:25px}.setup .intro h1 br{display:none}.stats{gap:30px}.takeaways{grid-template-columns:1fr}.formula-card{padding:22px}}
@media(max-width:450px){.tabs{gap:22px;margin-right:-15px;padding-right:15px}.panel-title{margin-bottom:22px}.topic-choice{font-size:.8125rem}.topic-actions .link-button{font-size:.8125rem}.filter-row{align-items:flex-start;flex-direction:column;gap:7px}.study-heading h1{font-size:2rem}.question-meta .scope-badge{max-width:100%}.stats span{font-size:.75rem}}
.intro,.panel,.concept-list,.study-heading>div{min-width:0}h1,h2,h3,.source,.explanation,.concept-content,.formula-card p,.takeaway p,.quick-question p{overflow-wrap:anywhere}.topic-actions{flex-wrap:wrap}.check-row{flex-wrap:wrap}.check-row input{flex-shrink:0}
@media(max-width:800px){.setup,.study-layout,.calculation-grid{grid-template-columns:minmax(0,1fr)}}
.tabs,.tabs:focus-within{overflow-y:hidden}.tabs button:focus-visible{outline-offset:-3px}