:root {
  font-family: 'Segoe UI', Arial, sans-serif;
  color: #202943;
  background: #f4f6fa;
  font-synthesis: none;
  font-size: 16px;
  --blue: #304be8;
  --ink: #202943;
  --muted: #62708a;
  --line: #e1e6f0;
  --math: 'Cambria Math', Cambria, 'STIX Two Math', Georgia, serif;
}
* { box-sizing: border-box; }
body { margin: 0; }
button, input, textarea, select { font: inherit; }
button, a, summary, select { -webkit-tap-highlight-color: transparent; touch-action: manipulation; }
button, select, summary { cursor: pointer; }
button { transition: background .15s, border-color .15s; }
button:disabled { cursor: default; }
button:focus-visible, a:focus-visible, summary:focus-visible, input:focus-visible, select:focus-visible, textarea:focus-visible, .step:focus-visible {
  outline: 3px solid #8b9aff; outline-offset: 4px;
}
[hidden] { display: none !important; }
a { color: var(--blue); text-underline-offset: 3px; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }
.topbar { min-height: 82px; padding: 16px max(4vw, 24px); display: flex; align-items: center; gap: 26px; border-bottom: 1px solid var(--line); background: #fff; }
.brand { display: flex; align-items: center; gap: 11px; color: var(--ink); text-decoration: none; font-size: 31px; font-weight: 750; letter-spacing: -1.4px; }
.brand-symbol { width: 38px; height: 40px; display: grid; place-items: center; border-radius: 11px; background: var(--blue); color: #fff; font-family: var(--math); font-size: 32px; font-weight: 400; letter-spacing: 0; }
.brand-dot { color: var(--blue); }
.header-description { font-size: .875rem; color: var(--muted); padding-left: 26px; border-left: 1px solid var(--line); }
.version { margin-left: auto; font-size: .8125rem; color: #526386; background: #f4f6fb; border: 1px solid var(--line); padding: 7px 11px; border-radius: 6px; }
main { width: min(1392px, 100%); margin: auto; padding: 34px 4vw 0; }
.page-heading { display: flex; justify-content: space-between; align-items: center; gap: 24px; margin-bottom: 26px; }
.eyebrow { font-size: .6875rem; font-weight: 700; letter-spacing: .14em; color: var(--blue); margin: 0 0 10px; }
h1 { font-size: clamp(1.6rem, 2.5vw, 2rem); font-weight: 650; line-height: 1.25; letter-spacing: -.035em; margin: 0; }
.heading-note { font-size: .875rem; line-height: 1.65; color: var(--muted); margin: 0; text-align: right; }
.topic-switch { display: flex; flex-wrap: wrap; gap: 10px; margin-bottom: 20px; }
.topic-switch button { text-align: left; border: 1px solid var(--line); border-radius: 9px; padding: 12px 18px; background: #fff; color: var(--ink); }
.topic-switch button[aria-pressed=true] { border-color: var(--blue); background: #edf1ff; box-shadow: inset 0 -2px var(--blue); }
.topic-switch strong { display: block; font-size: .875rem; font-weight: 600; }
.topic-switch span { display: block; font-size: .75rem; color: var(--muted); margin-top: 4px; }
.calculator-navigation { display: flex; align-items: stretch; flex-wrap: wrap; gap: 18px 30px; margin-bottom: 24px; }
.calculator-tab { display: flex; align-items: center; gap: 13px; padding: 16px 22px; border: 1px solid var(--line); border-radius: 10px; background: #fff; color: var(--ink); text-align: left; }
.calculator-tab[aria-pressed=true] { background: var(--blue); border-color: var(--blue); color: #fff; box-shadow: 0 4px 12px #304be81a; }
.calculator-tab strong { display: block; font-size: 1rem; font-weight: 650; }
.calculator-tab small { display: block; margin-top: 5px; font-size: .8125rem; opacity: .85; }
.calculator-symbol { font-family: var(--math); font-size: 30px; }
.chapter-navigation { display: flex; flex-wrap: wrap; align-items: center; gap: 9px 14px; }
.chapter-label { color: var(--muted); font-size: .8125rem; }
.chapter-navigation .topic-switch { margin: 0; }
.calculator-help { font-size: .875rem; color: var(--muted); line-height: 1.65; margin: 0 0 12px; }
.detected-topic { margin: 14px 0 0; font-size: .8125rem; line-height: 1.6; color: #3f5791; }
.calculator-syntax { margin: -6px 0 20px; font-size: .8125rem; line-height: 1.75; color: var(--muted); }
.calculator-syntax summary { color: #405a9b; padding: 4px 0; }
.calculator-syntax p { margin: 9px 0; }
.calculator-syntax pre { white-space: pre-wrap; padding: 12px 15px; border-radius: 7px; background: #f3f6ff; color: var(--ink); font-family: var(--math); font-size: 1rem; line-height: 1.65; }
.practice-panel h3 { font-size: 1.125rem; margin-bottom: 8px; }
.practice-intro { font-size: .9375rem; line-height: 1.75; color: var(--muted); margin: 0 0 22px; }
.practice-panel > label { display: block; font-size: .875rem; font-weight: 600; margin: 18px 0 9px; }
.practice-panel textarea { display: block; width: 100%; resize: vertical; border: 1px solid #b6c3e6; border-radius: 9px; padding: 14px 16px; color: var(--ink); background: #fbfcff; font-family: var(--math); font-size: 1.125rem; line-height: 1.8; }
.practice-panel .practice-work { min-height: 220px; background: repeating-linear-gradient(#fbfcff, #fbfcff 31px, #e9edf7 31px, #e9edf7 32px); line-height: 32px; padding-top: 7px; }
.practice-note { margin: 9px 0 16px; color: var(--muted); font-size: .8125rem; line-height: 1.75; }
.practice-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 18px; }
.practice-actions button:disabled { opacity: .5; }
.practice-feedback { margin: 18px 0 0; border: 1px solid #d5dfef; border-radius: 8px; padding: 13px 16px; background: #f4f7fc; font-size: .9375rem; line-height: 1.75; }
.practice-feedback[data-status=correct] { color: #235c49; background: #edf8f2; border-color: #bbdec9; }
.practice-feedback[data-status=incorrect] { color: #913e40; background: #fff5f3; border-color: #eed0c9; }
.practice-feedback[data-status=partial] { color: #74561a; background: #fff9ed; border-color: #e9dab6; }
.practice-hints { margin-top: 24px; padding: 18px; background: #f8faff; border: 1px dashed #b2c2f1; border-radius: 10px; }
.practice-hints h4 { margin: 0 0 8px; font-size: .9375rem; color: #405ca8; }
.practice-hints p { font-size: .9375rem; line-height: 1.75; }
.practice-hints .practice-note { font-size: .8125rem; }
.practice-hints .extra-hint { padding-top: 8px; border-top: 1px solid #dce3f7; }
.practice-revealed-step { margin-top: 18px; padding: 16px; border: 1px solid #d9e3f5; border-radius: 8px; background: #fff; }
.calculus-math math { font-size: 1em; vertical-align: middle; }
.finance-fields label, #algebra-fields > label { display: block; font-size: .875rem; font-weight: 600; margin-bottom: 9px; }
.finance-fields input, .finance-fields select { width: 100%; min-height: 45px; padding: 10px 12px; border: 1px solid #c7d0e4; border-radius: 7px; color: var(--ink); background: #fff; }
.finance-fields input { font-variant-numeric: tabular-nums; }
.finance-fields [data-finance-field] { margin-bottom: 18px; }
.finance-fields label span { float: right; color: var(--muted); font-weight: 400; }
.course-coverage { padding-left: 19px; font-size: .8125rem; line-height: 1.65; color: var(--muted); }
.course-coverage li + li { margin-top: 10px; }
.workspace { display: grid; grid-template-columns: minmax(310px, 350px) minmax(0, 1fr); align-items: start; gap: 24px; }
.input-panel, .solution-panel { min-width: 0; background: #fff; border: 1px solid var(--line); border-radius: 14px; box-shadow: 0 4px 18px #24355d06; }
.input-panel { padding: 24px; }
.panel-label { display: flex; align-items: center; gap: 10px; margin-bottom: 23px; }
h2 { font-size: 1.0625rem; font-weight: 650; margin: 0; letter-spacing: -.015em; }
.small-symbol { width: 29px; height: 29px; border-radius: 8px; display: grid; place-items: center; font-family: var(--math); font-size: 23px; font-style: italic; color: var(--blue); background: #eef1ff; }
form > label, legend, .method-field > label { display: block; font-size: .875rem; font-weight: 600; margin-bottom: 9px; }
.input-wrap { position: relative; }
.input-wrap textarea { display: block; width: 100%; min-height: 136px; padding: 14px 36px 14px 16px; resize: vertical; border: 1.5px solid #b6c3f0; border-radius: 9px; background: #fbfcff; color: var(--ink); font-family: var(--math); font-size: 1.375rem; line-height: 1.65; }
.input-wrap textarea[aria-invalid=true] { border-color: #b13d4b; }
.input-wrap button { position: absolute; top: 8px; right: 3px; min-width: 38px; min-height: 40px; border: 0; border-radius: 6px; background: transparent; color: var(--muted); font-size: 23px; }
.input-wrap button:hover { color: var(--ink); background: #edf1fc; }
.math-keys { display: flex; gap: 4px; margin-top: 9px; }
.math-keys button { flex: 1; min-width: 0; min-height: 39px; border: 1px solid var(--line); border-radius: 6px; background: #fff; color: #405071; font-family: var(--math); font-size: 17px; }
.math-keys button:hover { background: #f0f3ff; border-color: #aab8f4; }
.input-help, .method-help { font-size: .8125rem; line-height: 1.65; color: var(--muted); margin: 10px 0 20px; }
.input-preview { margin-top: 14px; padding: 12px 14px; background: #f2f5ff; border: 1px solid #dce4fa; border-radius: 8px; }
.input-preview > span { display: block; color: #52668f; font-size: .75rem; margin-bottom: 10px; }
.expression-view { overflow-x: auto; max-width: 100%; padding: 4px 1px; font-size: 1.3rem; }
.expression-line { min-height: 2em; padding: 4px 0; }
.expression-view math { font-size: 1em; }
.division-field { margin-top: 14px; padding: 12px; border: 1px solid #d8e1f5; border-radius: 8px; }
.division-field legend { padding: 0 4px; font-size: .8125rem; }
.division-field label { display: flex; align-items: flex-start; gap: 8px; font-size: .8125rem; line-height: 1.5; cursor: pointer; }
.division-field label + label { margin-top: 10px; }
.division-field input { accent-color: var(--blue); margin-top: 4px; }
.division-field small { display: block; font-family: var(--math); font-size: .875rem; color: var(--muted); margin-top: 3px; }
.method-field { padding-top: 2px; }
.method-field select { display: block; width: 100%; min-height: 45px; padding: 9px 10px; color: var(--ink); background: #fff; border: 1px solid #c7d0e4; border-radius: 7px; font-size: .9375rem; }
.method-help { margin-bottom: 22px; }
.error { font-size: .875rem; line-height: 1.65; color: #923543; border: 1px solid #f0cbd1; background: #fff4f5; border-radius: 8px; padding: 12px; margin: 0 0 20px; }
fieldset { border: 0; padding: 0; margin: 0 0 18px; min-width: 0; }
legend { padding: 0; }
.mode-option { display: flex; align-items: center; gap: 10px; padding: 11px 12px; margin-top: 7px; border: 1px solid var(--line); border-radius: 8px; cursor: pointer; }
.mode-option:has(input:checked) { border-color: #aab9f2; background: #f3f5ff; }
.mode-option input, .explanation-toggle input { accent-color: var(--blue); width: 16px; height: 16px; flex-shrink: 0; margin: 0; }
.mode-option strong { font-size: .875rem; font-weight: 600; display: block; }
.mode-option small { font-size: .8125rem; color: var(--muted); display: block; margin-top: 3px; line-height: 1.5; }
.mode-icon { margin-left: auto; font-size: 22px; color: #6478b4; }
.primary-button { display: flex; justify-content: space-between; align-items: center; gap: 12px; width: 100%; min-height: 49px; padding: 12px 17px; color: #fff; background: var(--blue); border: 1px solid var(--blue); border-radius: 8px; font-weight: 600; font-size: .9375rem; }
.primary-button:hover, .next-button:hover { background: #243cc7; }
.primary-button span:last-child { font-size: 23px; line-height: 1; }
.keyboard-tip { text-align: center; margin: 9px 0 0; font-size: .75rem; color: var(--muted); }
.examples { margin-top: 23px; padding-top: 21px; border-top: 1px solid var(--line); }
h3 { font-size: .9375rem; font-weight: 650; margin: 0 0 12px; }
.example-list { display: grid; gap: 2px; }
.example-list button { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 6px 10px; min-height: 44px; padding: 10px 0; text-align: left; border: 0; border-bottom: 1px solid #edf0f6; background: transparent; color: var(--muted); font-size: .8125rem; }
.example-list button:last-child { border-bottom: 0; }
.example-list button:hover { color: var(--blue); }
.example-math { color: #394b71; font-family: var(--math); font-size: 1rem; overflow-wrap: anywhere; }
.scope { margin-top: 19px; color: var(--muted); font-size: .875rem; line-height: 1.7; }
.scope summary { color: #475d90; font-size: .8125rem; padding: 3px 0; }
.scope p:last-child { margin-bottom: 0; }
.solution-panel { overflow: hidden; min-height: 600px; }
.solution-toolbar { padding: 20px 28px; min-height: 72px; display: flex; align-items: center; justify-content: space-between; gap: 14px; border-bottom: 1px solid var(--line); }
.solution-toolbar > div { display: flex; align-items: center; gap: 10px; }
.notebook-icon { color: #637497; font-size: 24px; }
.kind-tag { background: #f1f4fa; color: #53678c; padding: 6px 10px; border-radius: 5px; font-size: .75rem; text-align: center; line-height: 1.5; }
.solution-options { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 12px; padding: 13px 28px; background: #fcfdff; border-bottom: 1px solid var(--line); }
.glossary-bar { display: flex; align-items: center; justify-content: space-between; gap: 8px 18px; flex-wrap: wrap; padding: 10px 28px; border-bottom: 1px solid var(--line); }
.glossary-bar p { margin: 0; color: var(--muted); font-size: .75rem; line-height: 1.6; }
#open-glossary { min-height: 40px; padding: 7px 10px; border: 1px solid #d9e1f6; border-radius: 7px; color: #4057a7; background: #f8faff; font-size: .8125rem; white-space: nowrap; }
#open-glossary span { display: inline-grid; place-items: center; width: 17px; height: 17px; margin-left: 5px; border: 1px solid #a4b4e5; border-radius: 50%; font-size: .6875rem; }
.term-link { display: inline; border: 0; border-radius: 2px; padding: 0; color: inherit; background: transparent; font: inherit; text-align: inherit; text-decoration: underline dotted #92a4cd; text-underline-offset: 4px; text-decoration-thickness: 1px; }
.term-link:hover { color: var(--blue); text-decoration-style: solid; background: #eaf0ff; }
.hint-box .extra-hint { margin: 16px 0 0; border-top: 1px solid #dce3f7; padding-top: 12px; }
.extra-hint > summary { color: #304ea8; font-size: .875rem; font-weight: 600; padding: 8px 0; }
.hint-box .extra-hint > p { margin-top: 12px; }
.extra-hint ol { margin: 12px 0; padding-left: 23px; color: #4c6086; font-size: .9375rem; line-height: 1.75; }
.extra-hint li + li { margin-top: 8px; }
.hint-box .teaching-example-label { font-size: .75rem; font-weight: 600; color: #52658d; }
.math-block.teaching-example { font-size: 1.125rem; margin-top: 8px; background: #fff; padding: 12px 14px; border: 1px solid #e0e6f7; border-radius: 7px; }
#term-dialog { width: min(560px, calc(100% - 28px)); max-height: 85vh; max-height: 85dvh; padding: 0; border: 1px solid var(--line); border-radius: 14px; color: var(--ink); background: #fff; box-shadow: 0 20px 80px #12224740; }
#term-dialog[open] { display: flex; flex-direction: column; }
#term-dialog::backdrop { background: #15234170; }
.term-header { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 14px 18px 10px 24px; border-bottom: 1px solid var(--line); flex-shrink: 0; }
#term-heading { font-size: 1.25rem; line-height: 1.5; }
#term-heading:focus { outline: none; }
#term-close { flex-shrink: 0; width: 44px; height: 44px; border: 0; border-radius: 7px; background: #f4f6fb; color: #51617e; font-size: 25px; }
#term-close:hover { background: #e9eef9; }
#term-back { align-self: flex-start; flex-shrink: 0; min-height: 44px; margin: 8px 18px 0; padding: 8px 6px; border: 0; border-radius: 4px; background: transparent; color: #4057a7; font-size: .875rem; }
#term-back:hover { text-decoration: underline; }
#term-content { min-height: 0; overflow-y: auto; overscroll-behavior: contain; padding: 18px 24px 26px; }
.term-definition, .glossary-intro { margin: 0; font-size: 1rem; line-height: 1.8; }
.glossary-intro { color: var(--muted); font-size: .9375rem; }
.term-example-label { color: #526799; font-size: .6875rem; font-weight: 700; letter-spacing: .1em; margin: 22px 0 8px; }
.math-block.term-example { padding: 14px 16px; border-left: 3px solid #b3c4f8; background: #f4f7ff; border-radius: 4px; font-size: 1.125rem; }
.term-source-label { color: var(--muted); font-size: .75rem; margin: 24px 0 7px; }
.term-source { font-size: .8125rem; line-height: 1.7; overflow-wrap: anywhere; }
.term-group { margin-top: 24px; }
.term-group h3 { color: #53678c; font-size: .8125rem; margin-bottom: 10px; }
.term-list { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 180px), 1fr)); gap: 8px; }
.term-list button { text-align: left; min-height: 44px; padding: 10px 12px; border: 1px solid var(--line); border-radius: 7px; background: #fbfcff; color: var(--ink); font-size: .875rem; }
.term-list button:hover { background: #eff3ff; border-color: #b4c3ed; }
.segmented-control { display: inline-flex; padding: 3px; background: #eef1f8; border-radius: 7px; }
.segmented-control button { min-height: 34px; padding: 5px 14px; border: 1px solid transparent; border-radius: 5px; color: #53678c; background: transparent; font-size: .8125rem; }
.segmented-control button[aria-pressed=true] { color: var(--blue); background: #fff; border-color: #dbe2f5; box-shadow: 0 1px 3px #263c5e0d; }
.explanation-toggle { display: flex; align-items: center; gap: 8px; margin-left: auto; font-size: .8125rem; color: #526487; cursor: pointer; min-height: 36px; }
#solution { padding: 25px 28px 30px; }
.problem-strip { display: flex; align-items: flex-start; justify-content: space-between; gap: 15px; margin-bottom: 23px; }
.problem-strip > div { min-width: 0; }
.problem-strip p { margin: 0 0 7px; color: var(--muted); font-size: .6875rem; font-weight: 650; letter-spacing: .08em; }
.step-count { color: var(--muted); font-size: .8125rem; white-space: nowrap; margin-top: 3px; }
.math-block { font-family: var(--math); font-size: 1.375rem; line-height: 1.8; letter-spacing: .01em; overflow-wrap: anywhere; }
.math-line { min-height: 1.5em; white-space: pre-wrap; }
math { font-family: var(--math); font-size: 1.1em; vertical-align: middle; }
.source-math { font-size: 1.3125rem; color: #334567; }
.answer-card { padding: 19px 22px 20px; background: #f0f4ff; border: 1px solid #d2dcfc; border-radius: 10px; margin-bottom: 27px; }
.answer-topline { display: flex; align-items: center; justify-content: space-between; gap: 16px; }
.answer-label { color: #4c60a8; font-size: .6875rem; font-weight: 750; letter-spacing: .12em; }
.answer-check { display: grid; place-items: center; width: 24px; height: 24px; color: var(--blue); background: #dfe7ff; border-radius: 50%; font-size: .875rem; }
.answer-math { font-size: 1.625rem; color: #263fa8; line-height: 1.6; margin: 7px 0; }
.answer-card p { font-size: .875rem; line-height: 1.65; color: #5c6d96; margin: 6px 0 0; }
.steps-header { display: flex; align-items: center; justify-content: space-between; gap: 14px; margin-bottom: 23px; }
.steps-header h3 { margin: 0; }
.steps-header span { color: var(--muted); font-size: .75rem; }
.steps { list-style: none; margin: 0; padding: 0; }
.step { position: relative; padding: 0 0 28px 42px; min-width: 0; scroll-margin: 24px; border-radius: 4px; }
.step:not(:last-child)::before { content: ''; position: absolute; left: 13px; top: 33px; bottom: 6px; width: 1px; background: #dfe6f3; }
.step-number { position: absolute; top: 0; left: 0; display: grid; place-items: center; width: 28px; height: 28px; border-radius: 50%; background: #f0f3fc; border: 1px solid #dce4f7; color: #5066a7; font-weight: 650; font-size: .75rem; }
.step h4 { font-size: 1rem; font-weight: 600; line-height: 1.5; padding-top: 2px; margin: 0 0 12px; }
.step-math { background: #f8f9fc; border: 1px solid #ecf0f6; border-radius: 8px; padding: 10px 15px; margin: 9px 0 13px; }
.operation { display: inline-block; max-width: 100%; padding: 4px 10px; margin: 0 0 1px; color: #314caf; border: 1px solid #dce4fc; border-radius: 5px; background: #f1f4ff; font-size: 1rem; line-height: 1.7; }
.step details { margin-top: 12px; }
.step summary { width: fit-content; font-size: .8125rem; color: #475fad; padding: 3px 0; }
.step summary:hover { color: var(--blue); }
.explanation { color: #53627e; font-size: .9375rem; line-height: 1.8; margin: 9px 0; }
.paper-note { padding: 12px 14px; margin-top: 12px; border-left: 2px solid #c3d0f2; background: #fafbfe; color: #586984; font-size: .875rem; line-height: 1.75; }
.paper-note strong { display: block; color: #5b6e9e; font-size: .625rem; letter-spacing: .1em; font-weight: 700; margin-bottom: 5px; }
.matrices { display: flex; flex-wrap: wrap; gap: 16px 24px; margin-top: 12px; }
.matrix-figure { min-width: 0; max-width: 100%; margin: 6px 0 16px; }
.matrix-figure figcaption { font-size: 1rem; font-family: var(--math); color: #42557e; margin-bottom: 5px; }
.matrix-frame { max-width: 100%; overflow-x: auto; padding: 3px 0; }
.matrix-table { width: auto; border-collapse: separate; border-spacing: 0; font-family: var(--math); font-size: 1.3125rem; line-height: 1.5; }
.matrix-table th, .matrix-table td { text-align: center; padding: 8px 14px; min-width: 55px; white-space: nowrap; font-weight: 400; }
.matrix-table thead th { font-family: 'Segoe UI', Arial, sans-serif; font-size: .8125rem; color: #576e9a; padding: 0 12px 8px; }
.matrix-table .row-label { min-width: 0; text-align: right; padding: 8px 10px 8px 0; font-family: 'Segoe UI', Arial, sans-serif; font-size: .6875rem; color: #6b7d9d; }
.matrix-table tbody td { background-color: #fbfcfe; }
.matrix-table tbody td:first-of-type { border-left: 2px solid #7b8eb5; }
.matrix-table tbody td:last-child { border-right: 2px solid #7b8eb5; }
.matrix-table tbody tr:first-child td:first-of-type { background-image: linear-gradient(#7b8eb5, #7b8eb5); background-size: 7px 2px; background-repeat: no-repeat; background-position: top left; }
.matrix-table tbody tr:first-child td:last-child { background-image: linear-gradient(#7b8eb5, #7b8eb5); background-size: 7px 2px; background-repeat: no-repeat; background-position: top right; }
.matrix-table tbody tr:last-child td:first-of-type { box-shadow: inset 0 -2px 0 -1px #7b8eb5; }
.matrix-table tbody tr:last-child td:last-child { box-shadow: inset 0 -2px 0 -1px #7b8eb5; }
.matrix-table .rhs-cell { border-left: 1px solid #b9c6e0; color: #304779; }
.matrix-table .active-row td, .matrix-table .active-cell { background-color: #eaf0ff; color: #233f9f; }
.matrix-table .active-row .row-label { color: #304be8; }
.determinant .matrix-table tbody td { background-image: none !important; box-shadow: none !important; }
.matrix-help { font-size: .8125rem; line-height: 1.7; color: #5b6e90; background: #f4f7ff; padding: 11px 13px; border-radius: 6px; margin: -6px 0 23px; }
.verification { border-top: 1px solid var(--line); padding-top: 21px; margin-top: 0; }
.verification h3 { color: #28615a; font-size: .9375rem; }
.verification p { color: var(--muted); font-size: .875rem; line-height: 1.7; margin: 6px 0; }
.verify-math { color: #2c645b; font-size: 1.1875rem; margin-top: 10px; }
.substitution { color: #5b6d8b; font-size: 1.125rem; }
.guided-intro { background: #f4f6ff; border: 1px solid #dce3fb; border-radius: 9px; padding: 15px 17px; margin-bottom: 23px; }
.guided-intro strong { color: #3e56a5; font-size: .9375rem; }
.guided-intro p { color: #5b6d90; font-size: .875rem; line-height: 1.75; margin: 6px 0 0; }
.step-progress { appearance: none; display: block; width: 100%; height: 4px; border: 0; border-radius: 3px; background: #edf1fa; margin: -9px 0 26px; overflow: hidden; }
.step-progress::-webkit-progress-bar { background: #edf1fa; }
.step-progress::-webkit-progress-value { background: #7288e8; }
.step-progress::-moz-progress-bar { background: #7288e8; }
.hint-box { margin-left: 42px; padding: 19px; background: #fafbff; border: 1px dashed #acbce8; border-radius: 9px; }
.hint-box h4 { font-size: .875rem; color: #4e64a4; margin: 0 0 8px; }
.hint-box p { font-size: .9375rem; line-height: 1.75; color: #546682; margin: 0; }
.hint-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 17px; }
.next-button, .all-button { min-height: 44px; border-radius: 7px; font-size: .875rem; padding: 10px 14px; }
.next-button { background: var(--blue); border: 1px solid var(--blue); color: #fff; font-weight: 600; }
.all-button { border: 1px solid #d4dcef; color: #4c618f; background: #fff; }
.all-button:hover { background: #f0f3fc; }
.guided-answer { margin: 12px 0 24px; }
.stale-note, .method-notice { background: #fff8e9; color: #79602d; border: 1px solid #eadbb8; border-radius: 7px; padding: 12px 14px; font-size: .875rem; line-height: 1.7; margin: 0 0 20px; }
.is-stale .answer-card { background: #f5f6f9; border-color: #dfe4ed; }
.is-stale .answer-math { color: #62708a; }
.empty-message { color: var(--muted); font-size: 1rem; line-height: 1.75; padding: 24px 0; }
footer { display: flex; justify-content: space-between; align-items: center; gap: 20px; padding: 24px 2px 30px; color: #6e7e9a; font-size: .75rem; }
.footer-symbol { color: #637eac; font-size: 19px; margin-right: 5px; vertical-align: middle; }
@media (min-width: 1500px) { main { padding-left: 55px; padding-right: 55px; } }
@media (max-width: 1100px) {
  main { padding: 28px 24px 0; }
  .workspace { grid-template-columns: 310px minmax(0, 1fr); gap: 18px; }
  .input-panel { padding: 21px; }
  .solution-toolbar, .solution-options, .glossary-bar { padding-left: 20px; padding-right: 20px; }
  #solution { padding: 23px 20px 26px; }
  .step { padding-left: 37px; }
  .hint-box { margin-left: 0; }
  .steps-header span { display: none; }
  .matrix-table th, .matrix-table td { padding-left: 11px; padding-right: 11px; min-width: 48px; }
}
@media (max-width: 820px) {
  .workspace { grid-template-columns: minmax(0, 1fr); gap: 22px; }
  .topbar { min-height: 72px; padding: 14px 22px; }
  .header-description { display: none; }
  .heading-note { display: none; }
  main { padding: 25px 20px 0; }
  .input-panel { padding: 23px; }
  .solution-panel { min-height: 0; scroll-margin: 16px; }
  .example-list { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px; }
  .example-list button { flex-direction: column; align-items: flex-start; justify-content: center; padding: 10px 12px; border: 1px solid var(--line); border-radius: 7px; }
  .example-list button:last-child { border-bottom: 1px solid var(--line); }
  .solution-toolbar, .solution-options, .glossary-bar { padding-left: 23px; padding-right: 23px; }
  #solution { padding: 23px; }
}
@media (max-width: 480px) {
  .calculator-tab { width: 100%; }
  .chapter-navigation { width: 100%; }
  .chapter-navigation .topic-switch { width: 100%; }
  .topic-switch { gap: 7px; }
  .topic-switch button { flex: 1; min-width: 0; padding: 11px; }
  .topic-switch strong { font-size: .8125rem; }
  .topic-switch span { font-size: .6875rem; }
  .topbar { padding: 13px 17px; gap: 12px; }
  .brand { font-size: 28px; }
  .brand-symbol { width: 34px; height: 36px; font-size: 29px; }
  .version { max-width: 135px; font-size: .6875rem; }
  main { padding: 24px 12px 0; }
  h1 { font-size: 1.55rem; }
  .eyebrow { font-size: .625rem; }
  .page-heading { margin: 0 5px 23px; }
  .input-panel { padding: 20px; }
  .solution-toolbar, .solution-options, .glossary-bar { padding-left: 16px; padding-right: 16px; }
  .solution-toolbar h2 { font-size: 1rem; }
  .notebook-icon { display: none; }
  .kind-tag { max-width: 145px; font-size: .6875rem; }
  #solution { padding: 22px 16px; }
  .answer-card { padding: 17px; }
  .math-block { font-size: 1.25rem; }
  .answer-math { font-size: 1.5rem; }
  .operation { font-size: 1rem; }
  .step { padding-left: 33px; }
  .step h4 { font-size: .9375rem; }
  .step-math { padding: 10px; }
  .explanation { font-size: .9375rem; }
  .matrix-table { font-size: 1.125rem; }
  .matrix-table th, .matrix-table td { min-width: 40px; padding: 8px 9px; }
  .matrix-table .row-label { font-size: .625rem; padding-right: 7px; }
  .paper-note { padding: 11px 12px; }
  footer { align-items: flex-start; }
  footer span:last-child { text-align: right; max-width: 140px; line-height: 1.65; }
}
@media (prefers-reduced-motion: reduce) { * { transition: none !important; scroll-behavior: auto !important; } }