:root{--bg:#f5f4ee;--paper:#fff;--text:#172f30;--muted:#4f6261;--line:#dfe3de;--accent:#17675e;--soft:#eaf2eb;--orange:#bc5936;--shadow:0 5px 24px #173b3110}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--text);font-family:'IBM Plex Sans Arabic','DM Sans',system-ui,sans-serif;line-height:1.7}body.dark{--bg:#101d21;--paper:#172a2e;--text:#edf2e9;--muted:#b1c8c3;--line:#2b4144;--accent:#96cfa9;--soft:#253d39;--orange:#f7ad85;--shadow:none}button,input,select,textarea{font:inherit}button,a,input,textarea,select{touch-action:manipulation}button{cursor:pointer}button:disabled{cursor:default;opacity:.45}button:focus-visible,a:focus-visible{outline:3px solid var(--orange);outline-offset:4px}[hidden]{display:none!important}.topbar{display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line);padding:20px max(4%,calc((100vw - 1280px)/2));gap:20px;background:var(--paper)}.brand{display:flex;gap:10px;text-decoration:none;color:var(--text);font-size:24px;font-weight:700;line-height:1.3;direction:ltr}.brand-icon{background:var(--text);color:var(--paper);width:42px;height:46px;border-radius:12px;display:grid;place-items:center;font-family:Georgia,serif;font-size:36px}.brand-pro{color:var(--accent)}.brand small{display:block;font-size:8px;letter-spacing:1.8px;margin-top:3px;font-family:'DM Sans',sans-serif}nav{display:flex;gap:6px}.nav{border:none;background:none;padding:10px 18px;color:var(--muted);border-radius:8px;font-weight:500}.nav span{font-size:10px;margin-right:10px;opacity:1}.nav.active{color:var(--accent);background:var(--soft)}.icon-button{border:1px solid var(--line);background:var(--paper);color:var(--text);font-size:24px;width:43px;height:43px;border-radius:50%}main{max-width:1280px;margin:auto;padding:0 32px}.intro{display:flex;align-items:center;justify-content:space-between;padding:54px 0 35px;gap:30px}.eyebrow,.section-kicker{font-size:11px;font-weight:600;letter-spacing:.7px;color:var(--muted)}.eyebrow{display:flex;align-items:center;gap:9px}.dot{display:inline-block;width:7px;height:7px;background:var(--accent);border-radius:50%}.intro h1{font-size:clamp(34px,4vw,53px);line-height:1.4;font-weight:600;margin:14px 0}.intro h1 span{color:var(--accent)}.intro p{font-size:14px;color:var(--muted);margin:0}.intro-note{display:flex;align-items:center;gap:25px;margin-left:30px}.intro-note .note-number{font-family:Georgia,serif;font-size:112px;color:var(--orange);line-height:1}.intro-note b{font-size:15px}.intro-note p{font-size:12px;line-height:1.9;margin-top:8px}.engine-strip{display:flex;justify-content:space-between;gap:15px;font-size:11px;border-block:1px solid var(--line);padding:12px 0;margin-bottom:28px}.engine-strip .dot{margin-left:7px}.engine-strip b{font-weight:400}.engine-label{color:var(--muted);letter-spacing:1px;font-family:'DM Sans',sans-serif}.workspace{display:grid;grid-template-columns:250px minmax(0,1fr);gap:24px;align-items:start}.topics-card{background:var(--paper);padding:24px 16px;border:1px solid var(--line);border-radius:14px;position:sticky;top:20px}.topics-card>.section-kicker,.topics-card>h2{padding-inline:10px}.topics-card h2{font-size:18px;margin:6px 0 20px}.operation{width:100%;display:flex;text-align:right;gap:13px;align-items:center;padding:13px 12px;background:none;border:1px solid transparent;color:var(--text);border-radius:9px;margin-bottom:4px}.operation .symbol{font-family:Georgia,serif;font-size:23px;width:26px;text-align:center;color:var(--muted)}.operation b{font-size:13px;font-weight:500}.operation small{display:block;direction:ltr;text-align:right;font-size:10px;color:var(--muted);font-family:'DM Sans',sans-serif}.operation.active{background:var(--soft);border-color:var(--line)}.operation.active .symbol{color:var(--accent)}.operation:hover{background:var(--soft)}.sidebar-foot{border-top:1px solid var(--line);padding:18px 8px 0;margin-top:22px;color:var(--muted);display:flex;gap:12px}.sidebar-foot>span{font-size:26px}.sidebar-foot p{font-size:11px;margin:0}.lab-main{display:grid;gap:24px;min-width:0}.card{padding:28px;background:var(--paper);border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow);min-width:0}.card-top{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:20px}h2{font-size:21px;font-weight:600;margin:4px 0 8px}h2 small{font-family:'DM Sans',sans-serif;font-weight:400;font-size:12px;color:var(--muted);display:inline-block;margin-right:8px}.badge{border:1px solid var(--line);border-radius:20px;font-size:10px;padding:3px 10px;white-space:nowrap;color:var(--accent);background:var(--soft)}.examples{display:flex;flex-wrap:wrap;gap:8px;margin:0 0 24px}.example{font:12px 'DM Sans',sans-serif;border:1px solid var(--line);background:var(--bg);color:var(--text);border-radius:20px;padding:7px 13px;direction:ltr}.example:hover{border-color:var(--accent)}label{display:block;font-size:12px;font-weight:500;margin-bottom:7px}label>span{font-size:10px;color:var(--muted);margin-right:8px}textarea,input:not([type=checkbox]),select{border:1px solid var(--line);border-radius:8px;color:var(--text);background:var(--bg);padding:11px 13px;width:100%;outline:none}textarea:focus,input:focus,select:focus{border-color:var(--accent);box-shadow:0 0 0 3px var(--soft)}textarea{font:22px/1.8 'DM Sans',monospace;resize:vertical;min-height:100px;max-height:280px}input[dir=ltr]{font-family:'DM Sans',monospace}select{font-size:13px}.input-bottom{display:flex;justify-content:space-between;align-items:center;color:var(--muted);font-size:10px;gap:10px}.text-button{background:none;border:0;color:var(--accent);font-size:12px;padding:8px}.keyboard{display:grid;grid-template-columns:repeat(12,1fr);gap:5px;margin:14px 0 22px;direction:ltr}.keyboard button{background:var(--paper);border:1px solid var(--line);border-radius:6px;padding:7px 0;color:var(--text);font-family:Georgia,serif;font-size:14px}.keyboard button:hover{background:var(--soft)}.settings{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;margin-bottom:15px}.extra-fields{margin-top:16px}.check-label{display:flex;align-items:center;gap:8px;font-size:12px;cursor:pointer}.check-label input{accent-color:var(--accent)}.field-note{font-size:11px;color:var(--muted);line-height:1.9}.primary{display:flex;align-items:center;justify-content:space-between;width:100%;border:0;border-radius:8px;padding:13px 20px;background:#17675e;color:#fff;font-size:14px;font-weight:500;min-height:49px;gap:10px}.primary:hover{background:#11574f}.primary>span:last-child{font-size:19px}.secondary{padding:9px 15px;background:var(--paper);border:1px solid var(--line);color:var(--text);border-radius:7px;font-size:12px}.secondary:hover{background:var(--soft)}.error{background:#fff0eb;color:#8d351c;border:1px solid #e9b7a5;border-radius:8px;padding:14px;font-size:13px;margin-top:16px}.final-result{background:var(--soft);color:var(--accent);padding:24px 16px;border-radius:10px;margin-bottom:22px;text-align:center;overflow-x:auto;direction:ltr;font-size:22px;min-height:88px}.math{font-family:Georgia,serif}.katex-display{margin:.5em 0}.step-title{font-size:16px;margin-bottom:12px}.step-math{direction:ltr;padding:20px;background:var(--bg);border-radius:8px;overflow-x:auto;text-align:center;font-size:19px}.step-explanation{font-size:13px;line-height:2}.step-rule{font-size:11px;color:var(--accent)}.step-nav{display:flex;align-items:center;justify-content:space-between;border-top:1px solid var(--line);padding-top:18px;margin-top:18px;font-size:11px;color:var(--muted)}.warnings{border-right:3px solid var(--orange);background:var(--bg);padding:10px 14px;font-size:11px;color:var(--muted);margin:18px 0 8px}.warnings p{margin:4px 0}.method-strip{border-block:1px solid var(--line);display:grid;grid-template-columns:1fr 1.1fr auto;gap:30px;align-items:center;padding:28px 0;margin-top:40px}.method-strip h3{font-size:17px;margin:6px 0}.method-strip p{font-size:12px;color:var(--muted)}.method-strip a{font-size:12px;color:var(--accent);text-decoration:none}.references{font-size:12px;color:var(--muted);margin:20px 0 35px}.references summary{cursor:pointer}.references a{display:inline-block;margin:8px 0 8px 20px;color:var(--accent)}footer{max-width:1280px;margin:auto;padding:20px 32px 30px;display:flex;justify-content:space-between;color:var(--text);font-size:11px}.muted{color:var(--muted)}.practice-layout{display:grid;grid-template-columns:minmax(280px, .8fr) minmax(0,1.2fr);gap:24px;align-items:start}.empty{min-height:300px;text-align:center;display:flex;flex-direction:column;justify-content:center}.empty>span{font:70px Georgia,serif;color:var(--accent)}.empty h3{font-size:18px;margin:10px}.empty p{font-size:13px;color:var(--muted)}.exercise-math{direction:ltr;text-align:center;padding:30px 0;font-size:22px;overflow-x:auto}.exercise-actions{display:flex;gap:10px;margin-top:14px}.exercise-actions .primary{flex:1}.exercise-actions .secondary{white-space:nowrap}#feedback{font-size:13px;padding:14px;border-radius:8px;margin:15px 0;background:var(--soft);color:var(--accent)}#feedback.incorrect{color:var(--orange);background:var(--bg)}.stats-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;margin:28px 0}.stat{background:var(--bg);border:1px solid var(--line);border-radius:10px;padding:20px}.stat strong{font:35px 'DM Sans',sans-serif;display:block;color:var(--accent)}.stat span{font-size:12px;color:var(--muted)}.progress-row{padding:16px 0;border-top:1px solid var(--line);display:grid;grid-template-columns:130px 1fr 100px;gap:20px;align-items:center;font-size:12px}.progress-track{height:7px;background:var(--bg);border-radius:10px;overflow:hidden}.progress-fill{height:100%;background:var(--accent);border-radius:10px}.progress-row small{text-align:left;color:var(--muted)}#graph svg{display:block;width:100%;height:auto;min-height:220px;overflow:visible}.graph-legend{display:flex;gap:22px;justify-content:center;color:var(--accent);font-size:11px}.derivative-legend{color:var(--orange)}#graph text{fill:var(--muted);font:11px 'DM Sans',sans-serif}#graph .grid{stroke:var(--line);stroke-width:1}#graph .axis{stroke:var(--muted);stroke-width:1}#graph .curve{fill:none;stroke:var(--accent);stroke-width:2.4;stroke-linejoin:round}#graph .deriv{stroke:var(--orange);stroke-width:1.8;stroke-dasharray:5 4}.busy .dot{animation:pulse 1s infinite}@keyframes pulse{50%{opacity:.3}}@media(max-width:1000px){.intro-note{margin-left:0}.workspace{grid-template-columns:210px minmax(0,1fr);gap:18px}.card{padding:22px}.keyboard{grid-template-columns:repeat(6,1fr)}.method-strip{grid-template-columns:1fr 1fr}.method-strip a{grid-column:1/-1}.nav{padding:8px 12px}.topbar{padding-inline:24px}.engine-label{font-size:9px}}@media(max-width:700px){main{padding:0 18px}.topbar{padding:16px 18px;flex-wrap:wrap;gap:12px}.brand{font-size:22px;order:0}.icon-button{order:1;margin-right:auto}nav{order:2;flex-basis:100%;border-top:1px solid var(--line);padding-top:10px;justify-content:space-between}.nav{flex:1;padding:9px 4px;font-size:12px}.nav span{margin-right:5px}.intro{padding:32px 0 25px;display:block}.intro h1{font-size:38px}.intro p{font-size:12px}.intro-note{display:none}.eyebrow{font-size:9px}.engine-label{display:none}.engine-strip{font-size:10px}.workspace{display:block}.topics-card{position:static;padding:14px 12px;margin-bottom:18px}.topics-card>h2,.topics-card>.section-kicker,.sidebar-foot{display:none}#operations{display:flex;gap:6px;overflow-x:auto;padding-bottom:3px}.operation{flex:0 0 auto;width:auto;padding:7px 10px;gap:8px;margin:0;border:1px solid var(--line);border-radius:8px}.operation .symbol{font-size:19px;width:20px}.operation b{font-size:11px}.operation small{font-size:8px}.card{padding:20px 17px}.card-top{margin-bottom:15px}h2{font-size:19px}h2 small{display:block;margin-right:0;margin-top:4px}textarea{font-size:20px}.input-bottom span{font-size:8px}.settings{gap:10px}label{font-size:10px}.step-nav{gap:5px}.step-nav .secondary{padding:8px 10px}.method-strip{display:block;margin-top:28px;padding:22px 0}.practice-layout{display:block}.practice-layout>.card{margin-bottom:18px}.stats-grid{gap:9px}.stat{padding:12px}.stat strong{font-size:27px}.stat span{font-size:9px}.progress-row{grid-template-columns:90px 1fr 70px;gap:10px;font-size:11px}footer{padding:18px;display:block}footer>span{display:block;margin-bottom:7px}.badge{font-size:9px}.final-result{font-size:18px}.step-math{font-size:17px}.exercise-math{font-size:18px}}@media(prefers-reduced-motion:reduce){*{animation:none!important;scroll-behavior:auto!important}}
/* Local image reference, calculator input, and complete print report */
.image-input{border:1px dashed var(--line);background:var(--bg);padding:18px;border-radius:10px;margin-bottom:24px}.image-input h3{font-size:15px;margin:0}.image-input h3 small{font-size:10px;color:var(--muted);font-weight:400;margin-inline-start:5px}.image-input .card-top{margin-bottom:12px}.image-actions{display:flex;gap:10px;align-items:center;flex-wrap:wrap}.image-actions span{font-size:11px;color:var(--muted);overflow-wrap:anywhere}#question-preview{display:block;width:100%;max-height:360px;object-fit:contain;border:1px solid var(--line);border-radius:8px;background:var(--paper);margin:12px 0}#image-dialog{max-width:94vw;max-height:94vh;padding:18px;border:1px solid var(--line);border-radius:12px;background:var(--paper)}#image-dialog::backdrop{background:#001b29b3}#image-large{display:block;max-width:85vw;max-height:78vh;object-fit:contain;margin-top:12px}.input-preview{overflow:auto;direction:ltr;text-align:center;padding:16px;background:var(--soft);border-radius:8px;margin-top:10px}.symbol-reference,.source-reference{margin:16px 0;font-size:12px;color:var(--muted)}.symbol-reference summary,.source-reference summary{cursor:pointer;margin-bottom:12px}.symbol-reference table{width:100%;border-collapse:collapse;font-size:11px}.symbol-reference th,.symbol-reference td{padding:8px;border:1px solid var(--line);text-align:start}.source-reference label{margin-top:12px}.source-reference textarea{font:13px/1.8 inherit;min-height:75px}.mode-help{align-self:end}.keyboard{grid-template-columns:repeat(10,minmax(0,1fr))}.report-toolbar{display:flex;gap:12px;position:sticky;top:0;background:#fff;padding:16px 0;z-index:2}.report-toolbar .primary{width:auto}.report-open>header,.report-open>main,.report-open>footer{display:none!important}#report-sheet{max-width:850px;margin:auto;background:#fff;color:#172f30;min-height:100vh;padding:0 36px 40px;--paper:#fff;--bg:#f5f4ee;--text:#172f30;--muted:#627272;--line:#dfe3de;--accent:#17675e}#report-content h1{font-size:28px;margin:18px 0}#report-content p{font-size:13px;line-height:1.9}#report-content .report-stage{margin-top:30px;padding-top:18px;border-top:1px solid #dfe3de}#report-content h2{font-size:18px;margin-top:20px}#report-content h3{font-size:14px}.report-math{direction:ltr;text-align:center;padding:12px 5px;overflow:auto;background:#f7f8f5;margin:10px 0}.report-raw{direction:ltr;text-align:left;white-space:pre-wrap;overflow-wrap:anywhere}#report-content figure{margin:20px 0}#report-content figure img{display:block;max-width:100%;max-height:290px;margin:auto;object-fit:contain}#report-content figcaption{font-size:10px;color:#627272;text-align:center}#report-content a{font-size:12px;color:#17675e;overflow-wrap:anywhere}@media(max-width:700px){.keyboard{grid-template-columns:repeat(5,minmax(0,1fr))}.symbol-reference td:last-child{font-size:9px;word-break:break-all}.image-actions .secondary{font-size:11px;padding:9px}.image-input{padding:12px}#report-sheet{padding-inline:16px}.report-toolbar .primary,.report-toolbar .secondary{font-size:12px}.image-input .badge{white-space:normal}}
@media print{@page{size:A4;margin:16mm 14mm}body{background:#fff!important;color:#172f30!important}body>*{display:none!important}body>#report-sheet:not([hidden]){display:block!important;width:100%;max-width:none;padding:0;min-height:0}.report-toolbar{display:none!important}#report-content h1,#report-content h2,#report-content h3{break-after:avoid}#report-content .report-math,#report-content figure{break-inside:avoid}.report-math{overflow:visible;font-size:12pt;background:none}#report-content p{font-size:10pt}#report-content h2{font-size:13pt}#report-content img{max-height:65mm}a{color:#172f30!important;text-decoration:none}}
#ocr-review{padding:16px;margin-top:12px;border:1px solid var(--line);border-radius:12px}#ocr-text{min-height:90px;margin:8px 0}.topic-resources{border-top:1px solid var(--line);margin:18px 0;padding-top:12px}.topic-resources a{display:inline-block;font-size:12px;margin:4px 8px;color:var(--accent)}
.engine-settings{max-width:650px;margin:12px 0 24px}.engine-settings select{max-width:100%}.engine-settings label{display:block;font-size:12px;margin-bottom:6px}

/* 3.6: readable academic UI, inline tabbed keypad and clear action hierarchy. */
:root{--control-line:#788e85;--cta:#12594f;--cta-hover:#0b453d;--cta-text:#fff}
body.dark{--control-line:#78968c;--cta:#9ad6b1;--cta-hover:#b6e7c7;--cta-text:#102b26}
.field-note,.warnings,.sidebar-foot p,.keyboard-note{font-size:13px;line-height:1.9}
label{font-size:13px}label>span,.image-input h3 small,.operation small{font-size:12px}
.input-bottom,.input-bottom span{font-size:12px}.eyebrow,.section-kicker{font-size:12px}
textarea::placeholder,input::placeholder{color:var(--muted);opacity:1}
textarea,input:not([type=checkbox]),select{border-color:var(--control-line)}
.preview-region{min-width:0;margin:20px 0 14px;padding:16px 20px 20px;border:1px solid var(--control-line);border-radius:14px;background:var(--soft)}
.preview-heading,.keyboard-heading{display:flex;align-items:center;justify-content:space-between;gap:12px;font-size:13px;color:var(--text)}
.preview-heading>span,.keyboard-heading>span{color:var(--muted);font-size:12px}
.preview-region .input-preview{display:grid;align-items:center;min-height:116px;margin:12px 0 0;padding:18px 12px;font-size:clamp(24px,2.6vw,30px);line-height:1.8;border-radius:10px;background:var(--paper);overflow-x:auto;max-width:100%}
.preview-region .katex-display{margin:.5em 0}.preview-region .katex{font-size:1.15em}
.math-keyboard{position:static;margin:22px 0;padding:16px;border:1px solid var(--line);border-radius:14px;background:var(--bg);min-width:0}
.keyboard-heading{margin-bottom:12px}.keyboard-tabs{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:8px}
.keyboard-tabs [role=tab]{min-height:58px;min-width:0;padding:8px 5px;border:1px solid var(--control-line);border-radius:9px;background:var(--paper);color:var(--muted);line-height:1.5;font-size:13px;font-weight:600}
.keyboard-tabs [role=tab] small{display:block;font-size:11px;font-weight:400}
.keyboard-tabs [aria-selected=true]{background:var(--accent);color:var(--paper);border-color:var(--accent);box-shadow:inset 0 -3px 0 var(--text)}
body.dark .keyboard-tabs [aria-selected=true]{color:var(--bg)}
.math-keyboard .keyboard{grid-template-columns:repeat(5,minmax(0,1fr));gap:9px;margin:16px 0 12px}
.math-keyboard .keyboard button{min-height:48px;min-width:0;padding:8px 4px;font-size:22px;line-height:1.3;border-color:var(--control-line);border-radius:9px;background:var(--paper)}
.math-keyboard .keyboard button:hover{background:var(--soft);border-color:var(--accent)}
.math-keyboard .keyboard button:active{background:var(--soft)}
.keyboard-note{color:var(--muted);margin:8px 0 0;font-size:12px}
.primary{min-height:60px;margin-top:18px;padding:16px 22px;border-radius:12px;background:var(--cta);color:var(--cta-text);border:2px solid var(--cta);box-shadow:0 6px 16px #12594f24;font-size:18px;font-weight:700;transition:background-color .15s,box-shadow .15s}
.primary:hover{background:var(--cta-hover);border-color:var(--cta-hover);box-shadow:0 8px 20px #12594f32}
.primary .cta-label{display:flex;align-items:center;flex-wrap:wrap;gap:4px 14px}.cta-label small{font-size:12px;font-weight:500}
.primary:disabled{opacity:1;background:var(--soft);color:var(--muted);border-color:var(--control-line);box-shadow:none}
button:focus-visible,a:focus-visible,input:focus-visible,textarea:focus-visible,select:focus-visible{outline:3px solid var(--orange);outline-offset:3px}
@media(max-width:700px){
 .math-keyboard{padding:12px}.keyboard-heading>span{font-size:11px}
 .keyboard-tabs{gap:5px}.keyboard-tabs [role=tab]{font-size:12px;min-height:60px}.keyboard-tabs [role=tab] small{font-size:10px}
 .math-keyboard .keyboard{grid-template-columns:repeat(4,minmax(0,1fr));gap:8px}
 .preview-region{padding:12px;margin:18px 0 14px}.preview-region .input-preview{min-height:108px;padding:16px 10px;font-size:24px}
 .preview-heading{font-size:13px}.preview-heading>span{font-size:11px}
 input:not([type=checkbox]),select{font-size:16px}.primary{min-height:62px;font-size:18px;padding:15px 18px}.primary .cta-label{justify-content:flex-start}
}
@media(max-width:360px){.keyboard-heading{align-items:flex-start}.keyboard-heading>span{max-width:110px;text-align:end}.keyboard-tabs [role=tab] small{font-size:9px}.math-keyboard .keyboard{gap:6px}.preview-region .input-preview{font-size:22px}.cta-label small{font-size:11px}}
@media(prefers-reduced-motion:reduce){.primary{transition:none}.engine-strip.busy .dot{animation:none}}

.tutor-box{margin:20px 0 24px;padding:18px 20px;border:1px solid var(--control-line);border-inline-start:4px solid var(--accent);border-radius:12px;background:var(--soft);color:var(--text)}.tutor-header{display:flex;align-items:center;gap:10px}.tutor-header>span{color:var(--accent);font-size:24px}.tutor-header h3{margin:0;font-size:16px}.tutor-header small{display:inline-block;font-size:12px;font-weight:500;color:var(--muted);margin-inline-start:8px}.tutor-box p{font-size:14px;line-height:2;margin:12px 0 0}.tutor-box .field-note{font-size:12px;color:var(--muted)}@media(max-width:700px){.tutor-box{padding:16px}.tutor-header h3{font-size:15px}.tutor-header small{display:block;margin-inline-start:0}}
.detailed-choice{margin:18px 0;padding:12px 14px;background:var(--bg);border:1px solid var(--control-line);border-radius:9px;line-height:1.8}.detailed-choice input{width:18px;height:18px;flex-shrink:0}
/* 4.4 scientific palette, kept in the page flow on phones. */
.version-badge{align-self:center;font-size:11px;padding:4px 8px;border-radius:7px;background:var(--soft);color:var(--accent);white-space:nowrap}
.quick-palette{display:flex;align-items:center;gap:8px;background:#5c4482;padding:12px;border-radius:12px;overflow-x:auto;margin:16px 0;direction:ltr}
.quick-palette button,.extra-scalars button{flex:0 0 auto;min-width:46px;min-height:46px;border:1px solid #bfa6df;border-radius:8px;background:#6e5494;color:#fff;font-size:18px;padding:8px 12px}
.quick-palette button:hover,.extra-scalars button:hover{background:#432e63}.quick-palette #toggle-math-drawer{margin-inline-start:auto;font:inherit;direction:rtl;white-space:nowrap}
#math-drawer{border:1px solid var(--control-line);border-radius:14px;padding:16px;background:var(--soft);margin-bottom:20px}.drawer-heading{display:flex;justify-content:space-between;align-items:center;gap:10px}.drawer-heading button{background:var(--paper);color:var(--text);border:1px solid var(--control-line);border-radius:8px;min-height:44px;padding:6px 14px}
.drawer-extra{padding-top:14px;border-top:1px solid var(--control-line);margin-top:14px}.drawer-extra h3{font-size:15px}.drawer-action-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(100px,1fr));gap:8px}.drawer-action-grid button{min-height:46px;border:1px solid var(--control-line);background:var(--paper);color:var(--text);border-radius:8px;padding:8px}.drawer-action-grid button:disabled{opacity:1;color:var(--muted);background:var(--bg)}
.method-summary{background:var(--soft);border:1px solid var(--control-line);padding:18px;border-radius:14px;margin:24px 0}.method-summary h3{margin:0;font-size:17px}.parameter-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(100%,240px),1fr));gap:12px}.parameter-item{background:var(--paper);border:1px solid var(--control-line);border-radius:10px;padding:14px;min-width:0}.parameter-item b{font-size:13px}.parameter-item .math{overflow-x:auto;font-size:16px}
.verified-check{padding:18px;border-inline-start:4px solid var(--accent);background:var(--soft);margin:18px 0;border-radius:10px}.verified-check h3{font-size:16px;margin:0}.verified-check p{font-size:13px;color:var(--muted)}.verified-check .math{overflow-x:auto}
.all-steps-choice{margin:20px 0}.timeline-step{position:relative;border-inline-start:3px solid var(--control-line);padding:0 20px 22px;margin-inline-start:8px;min-width:0}.timeline-step h3{font-size:17px}.timeline-step p{font-size:14px}.timeline-step:before{content:'';position:absolute;inset-inline-start:-7px;top:9px;width:11px;height:11px;background:var(--accent);border-radius:50%}
@media(max-width:700px){#math-drawer{padding:10px}.quick-palette{gap:6px;padding:10px}.quick-palette button{min-width:44px;padding:8px}.brand .version-badge{font-size:10px}.timeline-step{padding-inline:14px}.method-summary{padding:12px}.drawer-action-grid{grid-template-columns:repeat(3,minmax(0,1fr))}.drawer-action-grid button{font-size:12px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}

/* 4.4.1: explicit colors override the general keyboard button background. */
.math-keyboard .extra-scalars button{background:var(--paper);color:var(--text);min-height:54px;font-size:18px;padding:10px 6px}
.math-keyboard .extra-scalars button:disabled{opacity:1;color:var(--muted);font-size:13px}
@media(max-width:700px){.quick-palette{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));overflow:visible;direction:ltr}.quick-palette button{min-width:0;width:100%;font-size:17px;padding:8px 4px}.quick-palette #toggle-math-drawer{grid-column:span 2;font-size:12px;margin:0}.quick-palette button:focus-visible{outline-offset:1px}}
/* 4.5 feedback uses engine events; rotating notes are educational, not progress claims. */
.loader-container{display:flex;flex-direction:column;align-items:center;justify-content:center;padding:20px 14px;margin:16px 0;background:var(--soft);border:1px solid var(--control-line);border-radius:12px;text-align:center;direction:rtl}
.spinner{width:36px;height:36px;border:4px solid var(--control-line);border-top-color:var(--accent);border-radius:50%;animation:calculus-spin 1s linear infinite;margin-bottom:8px;flex-shrink:0}
#loading-message{font-size:14px;color:var(--text);font-weight:600;margin:5px 0}#loading-tip{margin:5px 0;font-size:12px;max-width:56ch}
@keyframes calculus-spin{to{transform:rotate(360deg)}}
.solver-hints{margin-top:18px}.hint-button{min-height:44px;padding:9px 16px;border:1px solid var(--control-line);border-radius:9px;background:var(--soft);color:var(--text);font-weight:600}.hint-button:hover{border-color:var(--accent)}.hint-button:disabled{opacity:1;color:var(--muted)}
.hint-content{margin-top:12px;padding:14px;border-inline-start:4px solid var(--accent);background:var(--soft);border-radius:8px}.hint-content p{margin:0 0 8px;color:var(--text);font-size:14px}.hint-content .math{overflow-x:auto}.hint-level{display:block;font-size:12px;color:var(--muted);text-align:end}
.math,.exercise-math,.step-math,.report-math{direction:ltr;unicode-bidi:isolate}.katex,.MathJax{direction:ltr;unicode-bidi:isolate}
.graph-warning-banner{display:flex;align-items:flex-start;gap:10px;margin-top:14px;padding:12px 14px;border:1px solid var(--control-line);border-inline-start:4px solid var(--orange);background:var(--soft);color:var(--text);border-radius:8px;direction:rtl}.graph-warning-banner>span{font-size:20px;flex-shrink:0}.graph-warning-banner p{font-size:12px;line-height:1.9;margin:0}
.toast-container{position:fixed;inset-inline:0;bottom:calc(20px + env(safe-area-inset-bottom,0px));z-index:1000;display:flex;justify-content:center;pointer-events:none;padding:0 16px;direction:rtl}.toast{pointer-events:auto;display:flex;align-items:flex-start;gap:12px;max-width:600px;padding:15px 18px;background:#1e293b;color:#fff;border-inline-start:4px solid #fbbf24;border-radius:10px;box-shadow:0 8px 25px #0003}.toast strong{font-size:14px}.toast p{font-size:12px;line-height:1.8;color:#e2e8f0;margin:5px 0 0}.toast button{min-height:44px;min-width:60px;background:transparent;color:#fff;border:1px solid #94a3b8;border-radius:7px;padding:6px;font-size:12px;white-space:nowrap}
@media(prefers-reduced-motion:reduce){.spinner{animation:none}}@media print{.loader-container,.solver-hints,.toast-container{display:none!important}}

/* Visual mathematics: independent scroll area, with an always reachable source toggle. */
.editor-toolbar{display:flex;gap:12px;align-items:center;flex-wrap:wrap;margin:12px 0}
.editor-toolbar button{border:1px solid var(--muted);border-radius:8px;padding:10px 14px;background:var(--paper);color:var(--text);font:inherit;min-height:44px;cursor:pointer}
.editor-toolbar span{color:var(--muted);font-size:.86rem}
#visual-editor{min-width:0;max-width:100%}
#visual-expression{display:block;direction:ltr;unicode-bidi:isolate;text-align:left;width:100%;max-width:100%;min-height:88px;padding:18px 14px;border:2px solid var(--muted);border-radius:12px;background:var(--paper);color:var(--text);font-size:1.6rem;overflow-x:auto;--caret-color:var(--text);--selection-background-color:#c9dedc}
#visual-expression:focus-within{outline:3px solid #5f8a85;outline-offset:3px}
#visual-expression::part(virtual-keyboard-toggle){display:none}
#visual-expression::part(menu-toggle){display:none}
#visual-editor[hidden],#expression[hidden]{display:none!important}
@media(max-width:640px){#visual-expression{font-size:1.35rem;min-height:80px;padding:12px}.editor-toolbar{gap:8px}}

/* SYN identity: preserve approved colors with a light plate in either theme. */
.topbar .brand{align-items:center;flex-shrink:0;max-width:100%;gap:10px}
.syn-logo-plate{display:inline-flex;align-items:center;justify-content:center;background:#fff;border-radius:10px;padding:7px 10px;line-height:0}
.syn-brand-logo{display:block;width:220px;height:76px;object-fit:contain;max-width:100%}
.syn-report-logo{display:block;width:260px;max-width:100%;height:90px;object-fit:contain;background:#fff;border-radius:10px;padding:8px;margin:0 0 22px auto;break-inside:avoid}
@media(max-width:640px){.topbar .brand{gap:8px}.syn-brand-logo{width:172px;height:60px}.syn-logo-plate{padding:5px 8px}.syn-report-logo{width:220px;height:76px}}
@media(max-width:360px){.syn-brand-logo{width:148px;height:52px}.topbar .brand{gap:5px}}
@media print{.syn-report-logo{width:230px;height:80px;background:#fff!important;print-color-adjust:exact;-webkit-print-color-adjust:exact}}

/* SVG remains sharp when printed or saved as PDF, with its own light palette. */
.report-plot{margin:28px 0;padding-top:18px;border-top:1px solid #d8dfdc;break-inside:avoid;page-break-inside:avoid}
#report-content .report-plot-figure{margin:14px 0}
.report-plot-svg{background:#fff;border:1px solid #d8dfdc;border-radius:8px;padding:10px;overflow:hidden}
.report-plot-svg svg{display:block;width:100%;height:auto;max-height:110mm;direction:ltr}
#report-content .report-plot-caption,#report-content .report-plot-warning{color:#344b48;line-height:1.8;font-size:12px}
.report-plot-warning{border-right:3px solid #ac4729;padding:8px 12px;background:#fff7ed}
@media print{.report-plot{break-inside:avoid;page-break-inside:avoid}.report-plot-svg{background:#fff!important;print-color-adjust:exact;-webkit-print-color-adjust:exact}.report-plot-svg svg{width:100%;height:auto;max-height:95mm}.report-plot h2{break-after:avoid}}

/* Preserve the full expression on narrow screens and isolate math from RTL prose. */
.step-math,.math,.katex-display{max-width:100%;overflow-x:auto;overflow-y:hidden;direction:ltr;text-align:center;}
.example{display:inline-flex;gap:.5rem;align-items:center;flex-wrap:wrap;}
.example bdi{direction:ltr;unicode-bidi:isolate;}
.teaching-card{margin-block:1.2rem;padding-block:1rem;border-top:1px solid var(--line);}
.teaching-card p{line-height:1.8}.teaching-card a{overflow-wrap:anywhere}