:root{--red:#e52f4a;--red-dark:#bd1833;--ink:#17202a;--muted:#64707e;--paper:#f7f5f1;--card:#fff;--line:#ddd9d2;--soft:#efede8;--green:#137a54;--green-bg:#e8f6f0;--red-bg:#fff0f2;--shadow:0 14px 40px #18202a12}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;font-family:"Meiryo UI",Meiryo,"Yu Gothic UI",system-ui,sans-serif;background:var(--paper);color:var(--ink);line-height:1.6;overflow-x:hidden}body.dark{--paper:#14191f;--card:#20262d;--ink:#f5f2ed;--muted:#adb5c0;--line:#39414a;--soft:#2b323a;--green-bg:#153a2d;--red-bg:#402129}button,input,select{font:inherit}button{cursor:pointer}button:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid #e52f4a55;outline-offset:2px}button:disabled{cursor:not-allowed;opacity:.55}
header{height:68px;padding:0 max(24px,calc((100% - 1160px)/2));display:grid;grid-template-columns:auto 1fr auto;align-items:center;gap:36px;border-bottom:1px solid var(--line);background:color-mix(in srgb,var(--card) 95%,transparent);position:sticky;top:0;z-index:10;backdrop-filter:blur(10px)}.brand{border:0;background:none;font-size:24px;font-weight:950;letter-spacing:-1px;color:var(--ink);padding:8px 0}.brand b{color:var(--red)}nav{display:flex;justify-content:center;gap:2px}nav button{border:0;background:none;color:var(--muted);font-size:14px;font-weight:700;padding:12px 13px;border-radius:7px;white-space:nowrap}nav button:hover,nav button.current{background:var(--soft);color:var(--ink)}.badge{display:inline-grid;place-items:center;background:var(--red);color:white;border-radius:12px;min-width:20px;height:20px;padding:0 6px;font-size:11px;margin-left:3px}.header-actions{display:flex;gap:16px;align-items:center;font-size:12px;white-space:nowrap}#theme{border:1px solid var(--line);background:transparent;color:var(--ink);border-radius:50%;width:40px;height:40px}
main{max-width:1120px;margin:auto;padding:44px 24px 90px}.view{display:none}.view.active{display:block}.quiz-active nav{visibility:hidden}.narrow{max-width:850px;margin:auto}.hero{display:grid;grid-template-columns:1fr 260px;gap:60px;align-items:center;padding:38px 0 52px}.eyebrow{letter-spacing:.17em;font-size:11px;font-weight:900;color:var(--red);margin:0 0 8px}h1{font-size:clamp(42px,6.8vw,76px);line-height:1.04;letter-spacing:-.055em;margin:8px 0 22px}h1 em{font-style:normal;color:var(--red)}h2{font-size:27px;line-height:1.3;margin:0 0 18px}.hero>div>p:not(.eyebrow),.page-head>p:not(.eyebrow){color:var(--muted);max-width:600px}.primary,.secondary{min-height:48px;border-radius:8px;font-weight:800;padding:12px 20px}.primary{border:0;background:var(--red);color:#fff;box-shadow:0 8px 22px #e52f4a2c}.primary:hover{background:var(--red-dark)}.secondary{border:1px solid var(--line);background:var(--card);color:var(--ink)}.score-ring{aspect-ratio:1;border-radius:50%;border:18px solid var(--line);border-top-color:var(--red);display:grid;place-content:center;text-align:center;background:var(--card)}.score-ring strong{font-size:44px}.score-ring span{font-size:12px;color:var(--muted)}
.stats{display:grid;grid-template-columns:repeat(3,1fr);background:var(--card);border:1px solid var(--line);border-radius:12px;margin-bottom:54px;overflow:hidden}.stats article{padding:22px 24px;border-right:1px solid var(--line)}.stats article:last-child{border:0}.stats span,.stats small{display:block;color:var(--muted)}.stats strong{display:block;font-size:32px;line-height:1.2;margin:7px 0}.section-title{margin-bottom:16px}.modes{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;margin-bottom:60px}.modes button{display:grid;grid-template-columns:auto 1fr;gap:16px;text-align:left;align-items:center;padding:23px;background:var(--card);border:1px solid var(--line);border-radius:11px;color:var(--ink);transition:.18s}.modes button:hover,.categories button:hover{border-color:var(--red);transform:translateY(-2px);box-shadow:var(--shadow)}.modes b{color:var(--red);align-self:start}.modes strong,.modes small{display:block}.modes small{color:var(--muted);margin-top:3px}.modes i{grid-column:2;font-size:12px;color:var(--red);font-style:normal;font-weight:800}.category-head{display:flex;justify-content:space-between;align-items:end;margin-bottom:17px}.category-head label{color:var(--muted);font-size:12px}.category-head select,.filter-row select{display:block;background:var(--card);color:var(--ink);border:1px solid var(--line);min-height:44px;padding:7px 34px 7px 11px;border-radius:7px}.categories{display:grid;grid-template-columns:repeat(4,1fr);gap:10px}.categories button{padding:18px;text-align:left;background:var(--card);color:var(--ink);border:1px solid var(--line);border-radius:8px;transition:.18s;min-height:110px}.categories button:disabled:hover{border-color:var(--line);transform:none;box-shadow:none}.categories button span,.categories button i{display:block;color:var(--muted);font-size:12px;margin-top:5px}.categories button i{color:var(--red);font-style:normal;font-weight:800;margin-top:13px}
.page-head{padding:28px 0 18px}.page-head h1{font-size:48px;margin:4px 0 10px}.searchbox{height:60px;border:2px solid var(--line);background:var(--card);border-radius:11px;display:flex;align-items:center;padding:0 18px;gap:12px}.searchbox:focus-within{border-color:var(--red)}.searchbox span{font-size:28px;color:var(--muted)}.searchbox input{border:0;outline:0;background:none;color:var(--ink);width:100%;font-size:17px}.filter-row{display:flex;justify-content:space-between;align-items:center;margin:14px 0 22px;color:var(--muted);font-size:13px}.result-list{display:grid;gap:10px}.result-card{display:grid;grid-template-columns:1fr auto;gap:20px;align-items:center;background:var(--card);border:1px solid var(--line);border-radius:10px;padding:18px 20px}.result-card span,.result-card strong{display:block}.result-card span{font-size:11px;color:var(--red);font-weight:800}.result-card p{margin:5px 0 0;color:var(--muted);font-size:14px;line-height:1.55}.result-card button{white-space:nowrap}.notice{background:var(--card);border-left:4px solid var(--red);padding:15px 18px;border-radius:6px;margin-bottom:18px}.retry-all{margin-bottom:8px;width:max-content}.empty{text-align:center;border:1px dashed var(--line);border-radius:11px;padding:50px 20px;color:var(--muted)}.empty b{font-size:30px;color:var(--green)}.muted{color:var(--muted);text-align:center}
#history h2{margin-top:34px}.breakdown{background:var(--card);border:1px solid var(--line);border-radius:11px;padding:6px 20px}.breakdown article{display:grid;grid-template-columns:180px 1fr 50px;gap:18px;align-items:center;padding:17px 0;border-bottom:1px solid var(--line)}.breakdown article:last-child{border:0}.breakdown article div:first-child{display:flex;justify-content:space-between}.breakdown span{color:var(--muted);font-size:12px}.statbar{height:9px;background:var(--soft);border-radius:20px;overflow:hidden}.statbar i{height:100%;background:var(--red);display:block}.history-list{display:grid;gap:7px}.history-list>button{border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:9px;padding:13px 16px;display:grid;grid-template-columns:auto 1fr auto;gap:13px;align-items:center;text-align:left}.history-list small{display:block;color:var(--muted)}.history-list i{font-style:normal;color:var(--red);font-size:12px}.status{display:grid;place-items:center;width:30px;height:30px;border-radius:50%;font-weight:900}.status.ok{background:var(--green-bg);color:var(--green)}.status.ng{background:var(--red-bg);color:var(--red)}
.quiz-view{max-width:900px;margin:auto}.quiz-top{display:grid;grid-template-columns:auto 1fr auto auto;gap:18px;align-items:center}.ghost{min-height:44px;border:0;background:none;color:var(--muted);font-weight:700}.progress{height:7px;background:var(--line);border-radius:9px;overflow:hidden}.progress i{display:block;height:100%;background:var(--red);width:0;transition:width .25s}.quiz-top>span{font-size:13px;font-weight:800;white-space:nowrap}.mode-note{max-width:780px;margin:18px auto -38px;color:var(--muted);font-size:12px}.mode-note strong{color:var(--ink);margin-right:6px}.question{max-width:780px;margin:55px auto;background:var(--card);border:1px solid var(--line);border-radius:14px;padding:clamp(25px,5vw,50px);box-shadow:var(--shadow)}.meta{display:flex;gap:8px;flex-wrap:wrap}.meta span{font-size:11px;padding:5px 9px;border-radius:20px;background:var(--soft);color:var(--muted)}.meta span:first-child{color:var(--red);font-weight:900}.question h2{font-size:clamp(20px,2.8vw,29px);line-height:1.65;margin:25px 0;letter-spacing:.01em;white-space:pre-wrap}.choice{display:grid;grid-template-columns:32px 1fr;gap:11px;align-items:center;width:100%;text-align:left;margin:10px 0;padding:13px 15px;border:1px solid var(--line);border-radius:9px;background:var(--card);color:var(--ink);min-height:56px;line-height:1.5}.choice b{display:grid;place-items:center;border-radius:50%;background:var(--soft);width:30px;height:30px}.choice:hover:not(:disabled){border-color:var(--red);background:var(--red-bg)}.choice.correct{border:2px solid var(--green);background:var(--green-bg)}.choice.correct b{background:var(--green);color:white}.choice.wrong{border:2px solid var(--red);background:var(--red-bg)}.choice.wrong b{background:var(--red);color:white}#feedback{border-top:1px solid var(--line);margin-top:25px;padding-top:22px}.feedback-title{display:flex;align-items:center;gap:10px}.feedback-title span{display:grid;place-items:center;width:34px;height:34px;border-radius:50%;font-weight:900;color:#fff}.ok .feedback-title span{background:var(--green)}.ng .feedback-title span{background:var(--red)}#feedback h3{font-size:23px;margin:0}.ok #result{color:var(--green)}.ng #result{color:var(--red)}.explain{background:var(--soft);padding:16px 18px;border-radius:8px;margin-top:16px}.explain strong{font-size:13px}.explain p{margin:5px 0 0;line-height:1.75}.trap{color:var(--muted);font-size:13px}.quiz-actions{display:flex;justify-content:space-between;gap:12px;margin-top:28px}.quiz-actions .primary{margin-left:auto}.finish-card{text-align:center;max-width:650px;margin:45px auto;background:var(--card);padding:55px;border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow)}.finish-card h1{font-size:42px}.finish-score strong{font-size:70px;color:var(--red)}.finish-score span{display:block;color:var(--muted)}.finish-actions{display:flex;justify-content:center;gap:10px;margin-top:25px}#toast{position:fixed;left:50%;bottom:24px;transform:translate(-50%,20px);background:var(--ink);color:var(--card);padding:11px 17px;border-radius:8px;font-size:13px;opacity:0;pointer-events:none;transition:.2s;z-index:30;box-shadow:var(--shadow)}#toast.show{opacity:1;transform:translate(-50%,0)}
.data-figure{margin:20px 0 26px}.data-figure figcaption{font-weight:800;margin-bottom:8px}.table-scroll{overflow-x:auto;border:1px solid var(--line);border-radius:8px}.data-figure table{width:100%;border-collapse:collapse;min-width:440px;background:var(--card)}.data-figure th,.data-figure td{padding:10px 12px;text-align:center;border-right:1px solid var(--line);border-bottom:1px solid var(--line)}.data-figure th{background:var(--soft)}.bar-chart{display:grid;gap:9px}.bar-chart>div{display:grid;grid-template-columns:120px 1fr 42px;gap:8px;align-items:center;font-size:12px}.bar-chart i{display:block;height:20px;background:var(--red);border-radius:3px}.choice.selected{border:2px solid var(--red);background:var(--red-bg)}.submit-answer{display:block;margin:18px 0 0 auto}.answer-input{display:grid;gap:7px;font-weight:700}.answer-input input,.child-input{min-height:52px;border:2px solid var(--line);border-radius:8px;background:var(--card);color:var(--ink);padding:10px 12px;font-size:18px}.order-help{color:var(--muted)}.order-picked{background:var(--soft);padding:12px;border-radius:7px;font-weight:800;margin-bottom:14px}.inline-actions{display:flex;justify-content:space-between;gap:10px}.child{border:1px solid var(--line);border-radius:9px;padding:16px;margin:14px 0}.child legend{font-weight:800;padding:0 6px}.child label{display:block;padding:9px;border-radius:6px}.child input{margin-right:7px}.child-input{width:100%}
@media(max-width:820px){header{padding:0 16px;gap:12px;backdrop-filter:none}nav{position:fixed;bottom:0;left:0;right:0;height:64px;background:var(--card);border-top:1px solid var(--line);z-index:20;display:grid;grid-template-columns:repeat(4,1fr);padding-bottom:env(safe-area-inset-bottom)}.quiz-active nav{display:none}nav button{padding:7px 2px;font-size:11px;border-radius:0}.header-actions>#streak{display:none}main{padding-bottom:90px}.quiz-active main{padding-bottom:24px}.categories{grid-template-columns:repeat(3,1fr)}}
@media(max-width:600px){header{height:58px;grid-template-columns:1fr auto}.brand{justify-self:start}.header-actions{grid-column:2}main{padding:22px 15px 88px}.hero{grid-template-columns:1fr;padding:20px 0 34px}.hero h1{font-size:46px}.hero>div>p:not(.eyebrow){font-size:14px}.score-ring{display:none}.stats{grid-template-columns:1fr 1fr;margin-bottom:42px}.stats article{padding:16px}.stats article:last-child{display:none}.stats strong{font-size:28px}.modes{grid-template-columns:1fr;margin-bottom:48px}.modes button{min-height:94px}.category-head{align-items:start;gap:16px}.category-head h2{font-size:23px}.category-head label{max-width:140px}.category-head select{width:140px}.categories{grid-template-columns:1fr 1fr}.categories button{min-height:104px;padding:15px}.page-head{padding-top:14px}.page-head h1{font-size:38px}.searchbox{height:56px}.result-card{grid-template-columns:1fr;padding:16px}.result-card button{width:100%;min-height:48px}.retry-all{width:100%}#history .stats{grid-template-columns:1fr 1fr}#history .stats article:last-child{display:block;grid-column:1/-1;border-top:1px solid var(--line)}.breakdown article{grid-template-columns:1fr 42px;gap:9px}.breakdown article div:first-child{grid-column:1/-1}.history-list>button{grid-template-columns:auto 1fr}.history-list i{grid-column:2}.quiz-view{padding-top:0}.quiz-top{position:sticky;top:58px;z-index:5;background:var(--paper);margin:0 -15px;padding:10px 15px;grid-template-columns:auto 1fr auto;gap:10px}.quiz-top #timer{grid-column:3}.quiz-top #counter{display:none}.mode-note{margin:12px 0 -10px}.question{margin:24px 0 0;padding:20px 16px;border-radius:11px}.meta span{font-size:10px}.question h2{font-size:20px;line-height:1.7;margin:20px 0}.choice{min-height:58px;padding:12px 11px;margin:9px 0}.quiz-actions{position:sticky;bottom:0;background:var(--card);padding:12px 0 2px;margin-top:20px}.quiz-actions button{flex:1;padding:10px 8px}.finish-card{padding:36px 18px;margin:20px 0}.finish-card h1{font-size:35px}.finish-actions{flex-direction:column}.finish-actions button{width:100%}#toast{bottom:76px;width:max-content;max-width:90%;text-align:center}.quiz-active #toast{bottom:20px}}

/* Exercise reading density: shared across question types. */
.mode-note{max-width:800px;margin:14px auto -24px}.question{max-width:800px;margin:38px auto;padding:clamp(28px,3.5vw,38px)}.question h2{font-size:clamp(20px,2.15vw,25px);line-height:1.55;margin:20px 0 18px;letter-spacing:.005em;white-space:normal}.prompt-paragraph{display:block}.prompt-paragraph+.prompt-paragraph{margin-top:.8em}.long-reading h2{max-width:72ch;font-size:clamp(18px,1.8vw,21px);line-height:1.72;letter-spacing:0}.choice{grid-template-columns:30px minmax(0,1fr);gap:10px;align-items:start;min-height:52px;margin:7px 0;padding:11px 14px;font-size:15.5px;line-height:1.45}.choice b{width:28px;height:28px;margin-top:1px}.choice span{min-width:0;overflow-wrap:anywhere}#feedback{margin-top:20px;padding-top:18px}.explain{padding:14px 16px;margin-top:14px}.explain p{margin-top:4px;line-height:1.65}.data-figure{margin:14px 0 18px}.data-figure figcaption{font-size:14px;margin-bottom:6px}.table-scroll{max-width:100%;-webkit-overflow-scrolling:touch}.data-figure table{width:max-content;min-width:100%;font-size:13.5px;line-height:1.35}.data-figure th,.data-figure td{padding:8px 10px;white-space:nowrap}.bar-chart{gap:7px;max-width:100%}.bar-chart>div{grid-template-columns:minmax(80px,120px) minmax(80px,1fr) 42px;gap:8px}.bar-chart span{overflow-wrap:anywhere}.bar-chart i{max-width:100%;height:18px}.submit-answer{margin-top:16px}.answer-input input,.child-input{min-height:50px;font-size:17px}.order-help{margin:12px 0 8px}.order-picked{padding:10px 12px;margin-bottom:10px}.child{padding:14px;margin:11px 0}.child legend{line-height:1.5}.child label{display:flex;align-items:flex-start;gap:7px;min-height:44px;padding:9px;line-height:1.45}.child input{flex:0 0 auto;margin:4px 0 0}
@media(max-width:600px){.mode-note{margin:10px 0 -8px}.question{padding:18px 15px}.question h2{font-size:18px;line-height:1.58;margin:16px 0 14px}.prompt-paragraph+.prompt-paragraph{margin-top:.72em}.long-reading h2{max-width:none;font-size:16.5px;line-height:1.68}.choice{min-height:52px;margin:6px 0;padding:10px;font-size:15px}.data-figure{margin:12px 0 15px}.data-figure table{font-size:12.5px}.data-figure th,.data-figure td{padding:7px 8px}.bar-chart>div{grid-template-columns:82px minmax(72px,1fr) 36px;gap:6px}.child{padding:12px;margin:9px 0}.quiz-actions{padding-top:10px;margin-top:17px}}
.modes{grid-template-columns:repeat(4,1fr)}.session-wrong{margin-top:28px;text-align:left}.session-wrong h2{font-size:20px}.session-wrong>div{display:grid;gap:8px}.session-wrong button{display:grid;grid-template-columns:auto 1fr auto;gap:12px;align-items:center;width:100%;padding:12px;border:1px solid var(--line);border-radius:8px;background:var(--card);color:var(--ink);text-align:left}.session-wrong button span{color:var(--muted)}.session-wrong button i{color:var(--red);font-size:12px;font-style:normal}.all-correct{margin-top:24px;color:var(--green);font-weight:800}@media(max-width:900px){.modes{grid-template-columns:repeat(2,1fr)}}@media(max-width:600px){.modes{grid-template-columns:1fr}.session-wrong button{grid-template-columns:auto 1fr}.session-wrong button i{grid-column:2}}
.hero{display:block;max-width:760px;padding:38px 0 46px}.hero h1{font-size:clamp(38px,5vw,56px);line-height:1.12;letter-spacing:-.04em;margin:0 0 12px}.hero>div>p{margin:0 0 24px;font-size:16px}.hero .primary{box-shadow:none;padding-inline:24px}@media(max-width:600px){.hero{padding:22px 0 32px}.hero h1{font-size:36px}.hero>div>p{font-size:14px;margin-bottom:20px}.hero .primary{width:100%}}

.hero-menu-link{display:inline-flex;align-items:center;justify-content:center;text-decoration:none}.section-title{scroll-margin-top:84px}

#difficulty{display:none}

@media(max-width:600px){#home .stats article:last-child{display:block;grid-column:1/-1;border-top:1px solid var(--line);border-right:0}}

@media(max-width:820px){nav{grid-template-columns:repeat(3,1fr)}}

.stat-reset{margin-top:10px;padding:5px 9px;border:1px solid var(--line);border-radius:6px;background:transparent;color:var(--muted);font-size:11px}.stat-reset:hover{border-color:var(--red);color:var(--red)}

.confirm-dialog{width:min(420px,calc(100% - 30px));padding:26px;border:1px solid var(--line);border-radius:12px;background:var(--card);color:var(--ink);box-shadow:0 20px 60px #0003}.confirm-dialog::backdrop{background:#11182780}.confirm-dialog h2{font-size:21px;margin:0 0 10px}.confirm-dialog p{margin:0;color:var(--muted);font-size:14px;line-height:1.7}.confirm-dialog>div{display:flex;justify-content:flex-end;gap:10px;margin-top:22px}.confirm-dialog button{min-width:92px}

.categories{display:block}.category-group{margin-bottom:30px}.category-group h3{margin:0 0 12px;font-size:20px}.category-group>div{display:grid;grid-template-columns:repeat(4,1fr);gap:10px}@media(max-width:820px){.category-group>div{grid-template-columns:repeat(3,1fr)}}@media(max-width:600px){.category-group>div{grid-template-columns:repeat(2,1fr)}}

.mock-intro-card{max-width:680px;margin:45px auto;padding:42px;background:var(--card);border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow)}.mock-intro-card h1{font-size:clamp(32px,5vw,48px);margin:6px 0 14px}.mock-intro-card>p:not(.eyebrow){color:var(--muted)}.mock-intro-sections{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin:26px 0}.mock-intro-sections>div{display:flex;align-items:center;justify-content:space-between;padding:18px;border:1px solid var(--line);border-radius:9px;background:var(--soft)}.mock-intro-sections span{color:var(--red);font-weight:900}.mock-intro-note{font-size:13px}.mock-intro-actions{display:flex;justify-content:flex-end;gap:10px;margin-top:28px}.section-results{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin:28px 0}.section-results article{padding:18px;border:1px solid var(--line);border-radius:9px;background:var(--soft);text-align:left}.section-results span,.section-results strong,.section-results small{display:block}.section-results span,.section-results small{color:var(--muted)}.section-results strong{font-size:30px;margin:4px 0}@media(max-width:600px){.mock-intro-card{margin:18px 0;padding:26px 18px}.mock-intro-sections{grid-template-columns:1fr}.mock-intro-actions{flex-direction:column-reverse}.mock-intro-actions button{width:100%}.section-results{grid-template-columns:1fr}}

#quit{min-height:42px;padding:9px 14px;border:1px solid #dc3545;border-radius:8px;background:var(--card);color:#c62838;font-size:14px;font-weight:800;white-space:nowrap}#quit:hover{background:#fff0f2;border-color:#bd2030}

#home .stats{grid-template-columns:repeat(4,1fr)}@media(max-width:600px){#home .stats{grid-template-columns:repeat(2,1fr)}#home .stats article{display:block;grid-column:auto;border-top:0}#home .stats article:last-child{grid-column:auto;border-top:1px solid var(--line)}#home .stats article:nth-child(odd){border-right:1px solid var(--line)}#home .stats article:nth-child(n+3){border-top:1px solid var(--line)}}

/* Structured explanations and accessible stacked fractions. */
#explanation{margin-top:7px;font-size:15.5px;line-height:1.62}
#explanation .explain-heading{margin:15px 0 4px;font-size:14px;line-height:1.4;color:var(--ink)}
#explanation .explain-heading:first-child{margin-top:5px}
#explanation .explain-line{margin:0;line-height:1.62;overflow-wrap:anywhere}
#explanation .explain-gap{height:7px}
.correct-answer-display{display:flex;align-items:baseline;gap:10px;margin-top:16px;padding-top:12px;border-top:1px solid var(--line)}
.correct-answer-display>strong{color:var(--red);font-size:13px;flex:0 0 auto}
.math-frac{display:inline-flex;flex-direction:column;align-items:center;justify-content:center;vertical-align:middle;transform:translateY(-.08em);line-height:.9;font-size:.82em;min-width:1.45em;margin:0 .14em;font-variant-numeric:tabular-nums;white-space:nowrap}
.math-frac-num{box-sizing:border-box;width:100%;padding:0 .14em .09em;border-bottom:1.2px solid currentColor;text-align:center}
.math-frac-den{box-sizing:border-box;width:100%;padding:.09em .14em 0;text-align:center}
.choice .math-frac{margin-top:0;margin-bottom:0}
.choice .math-frac,#explanation .math-frac,.correct-answer-display .math-frac{min-width:1.45em}
@media(max-width:600px){#explanation{font-size:15px;line-height:1.6}#explanation .explain-line{line-height:1.6}#explanation .explain-heading{margin-top:13px}.explain{padding:13px 14px}.correct-answer-display{align-items:flex-start}}