@charset "UTF-8";
:root{color-scheme:light;--bg:#f4f4ef;--paper:#fff;--ink:#263531;--muted:#6d7973;--line:#dde4de;--green:#1b514e;--green-light:#eef5f0;--amber:#a46d29;--radius:20px;font-family:"BIZ UDGothic","Hiragino Kaku Gothic ProN","Yu Gothic",Meiryo,sans-serif;color:var(--ink);background:var(--bg);font-synthesis:none}
*{box-sizing:border-box}body{margin:0}button,input{font:inherit}button{cursor:pointer;touch-action:manipulation}button:disabled{cursor:default}button,a,input{-webkit-tap-highlight-color:transparent}button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid #c18c42;outline-offset:4px}button:disabled{opacity:.45}[hidden]{display:none!important}
.page-shell{max-width:1220px;margin:auto;padding:46px 34px 22px}.page-header{display:flex;justify-content:space-between;gap:24px;align-items:flex-start;margin-bottom:30px}.eyebrow{font-size:11px;font-weight:bold;letter-spacing:.12em;color:var(--green);margin:0 0 12px}.eyebrow span{letter-spacing:.04em;display:inline-block;margin-left:14px;border-left:1px solid #bdc9c0;padding-left:14px}h1{font-size:clamp(24px,3vw,34px);letter-spacing:.01em;line-height:1.45;margin:0 0 12px}h2{font-size:22px;line-height:1.65;margin:0}p{line-height:1.8}.intro{font-size:13px;color:var(--muted);margin:0}.text-button{border:0;background:transparent;padding:8px 0;color:var(--muted);font-size:12px;white-space:nowrap}.text-button:hover{text-decoration:underline}.workspace{display:grid;grid-template-columns:minmax(0,1fr) 290px;gap:26px;align-items:start}.lesson-column{min-width:0}
.progress-panel{margin-bottom:20px}.progress-caption{display:flex;justify-content:space-between;gap:12px;font-size:11px;color:var(--muted);margin-bottom:13px}.progress-caption>span:first-child{color:var(--green);font-weight:bold;letter-spacing:.12em}.steps{display:grid;grid-template-columns:repeat(8,1fr);gap:7px;list-style:none;padding:0;margin:0}.step-button{width:100%;height:36px;border:1px solid var(--line);border-radius:9px;background:#e9ede6;color:#8b958e;font-size:12px;font-weight:bold}.step-button.current{background:var(--green);color:white;border-color:var(--green)}.step-button.complete{background:#e2ede5;color:var(--green);border-color:#cadbcf}.step-button.current.complete{background:var(--green);color:white}.step-button:disabled{opacity:1}
.question-card,.video-card{background:var(--paper);border:1px solid var(--line);border-radius:var(--radius)}.question-card{padding:34px;min-height:400px}.question-content{animation:arrive .25s ease-out}.question-label{font-size:11px;color:var(--amber);font-weight:bold;letter-spacing:.08em;margin:0 0 13px}.question-title{font-size:22px;line-height:1.7;letter-spacing:.01em;margin:0 0 12px;outline:none}.question-description{font-size:13px;color:var(--muted);margin:0 0 24px}.options{display:grid;gap:10px;margin-top:26px}.option{display:flex;align-items:center;gap:14px;width:100%;text-align:left;padding:16px 18px;border:1px solid var(--line);border-radius:12px;background:white;color:var(--ink);font-size:15px;line-height:1.65;min-height:60px;transition:background .15s,border-color .15s,transform .15s}.option:hover:not(:disabled){border-color:#81a39a;background:#f8fbf8;transform:translateX(2px)}.option-letter{display:grid;place-items:center;flex:none;width:28px;height:28px;border-radius:8px;background:#f0f2ed;font-size:12px;color:var(--muted)}.option.correct{background:#edf7f0;border-color:#76a48c}.option.correct .option-letter{background:var(--green);color:white}.option.incorrect{background:#fff7ef;border-color:#d6ad85}.option:disabled{opacity:1}.option.unselected{opacity:.52}
.formula{padding:23px 18px;background:#f6f8f4;border-radius:14px;display:flex;align-items:center;justify-content:center;gap:14px;margin:25px 0;min-width:0}.formula-label{font-size:13px;line-height:1.6;flex-shrink:0}.formula-equals{font-size:23px;color:var(--muted)}.fraction{display:inline-flex;flex-direction:column;align-items:stretch;min-width:180px;max-width:100%;font-size:18px;text-align:center}.numerator{border-bottom:2px solid #657c70;padding:0 8px 12px;min-height:40px}.denominator{padding:12px 6px 0;display:flex;align-items:center;justify-content:center;gap:7px;min-height:48px}.blank{display:inline-block;min-width:95px;background:#e4ebe2;color:var(--green);border:1px dashed #799a8b;border-radius:7px;padding:4px 12px}.formula input{width:145px;min-width:0;padding:8px 7px;text-align:center;background:#fff;border:1.5px solid #94aaa0;border-radius:7px;font-size:17px;color:var(--ink)}.formula input.numeric{width:110px}.formula input:read-only{background:#e4ede4;border-color:transparent;color:var(--green);font-weight:bold}.inline-answer{display:flex;align-items:center;gap:11px;margin:26px 0 16px}.number-input{width:min(230px,75%);padding:15px 16px;font-size:24px;border:1.5px solid #a4b5ab;border-radius:10px;background:#fff;color:var(--ink)}.input-unit{font-size:14px;white-space:nowrap;color:var(--muted)}.input-guide{font-size:12px;color:var(--muted);margin:10px 0 18px}.submit-button{margin-top:16px}
.primary-button,.secondary-button{border-radius:10px;padding:13px 19px;font-weight:bold;font-size:13px;line-height:1.5;min-height:46px;display:inline-flex;justify-content:center;align-items:center;gap:15px}.primary-button{border:1px solid var(--green);background:var(--green);color:white}.primary-button:hover:not(:disabled){background:#103f3c}.secondary-button{border:1px solid var(--line);background:white;color:var(--muted)}.lesson-actions{display:flex;justify-content:space-between;align-items:center;gap:15px;margin-top:28px;padding-top:22px;border-top:1px solid #edf0eb}.feedback{margin-top:22px;padding:16px 18px;border-radius:11px;font-size:13px;line-height:1.85;background:#edf7f0;color:#285744;border-left:3px solid #659c7d}.feedback.wrong{background:#fff7ed;border-color:#c18c50;color:#785125}.feedback strong{display:block;font-size:14px;margin-bottom:3px}.hint-button{border:0;padding:7px 0;background:transparent;color:var(--muted);font-size:12px;text-decoration:underline;text-underline-offset:3px}.hint{font-size:13px;line-height:1.8;background:#f7f5ef;border-radius:9px;padding:13px 16px;margin-top:8px;color:#77674a}
.source{font-size:11px;color:var(--muted);margin:10px 0 17px;line-height:1.7}.original-question{font-size:14px;line-height:1.9;margin:16px 0}.data-table-wrap{margin:22px auto 24px;max-width:470px}.table-unit{text-align:right;font-size:11px;color:var(--muted);margin:0 0 8px}.data-table{border-collapse:collapse;width:100%;font-size:13px;font-variant-numeric:tabular-nums}.data-table th,.data-table td{padding:11px 14px;border-bottom:1px solid #e7ece5}.data-table thead{background:#eff3ee;color:var(--muted);font-size:11px}.data-table th{text-align:left;font-weight:normal}.data-table td,.data-table thead th:last-child{text-align:right}.data-table tr.relevant{background:#edf5ed}.data-table tr.relevant th{font-weight:bold;color:var(--green)}.calculated-values{display:flex;gap:9px;flex-wrap:wrap;margin:18px 0;font-size:12px}.calculated-values span{border-radius:7px;background:#f0f4ed;padding:9px 12px;color:var(--green)}.calculated-values b{margin-left:7px;font-variant-numeric:tabular-nums}.locked-note{font-size:12px;color:var(--green);margin:20px 0 -10px;line-height:1.7}.final-options{grid-template-columns:repeat(2,minmax(0,1fr))}.completion{margin-top:20px;padding:22px;background:var(--green-light);border:1px solid #c6ddce;border-radius:12px}.completion h3{font-size:18px;margin:0 0 12px;color:var(--green)}.completion p{font-size:13px;margin:6px 0}.completion-result{font-size:22px!important;font-weight:bold;color:var(--green)}
.video-card{margin-top:24px;padding:24px}.video-heading{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-bottom:18px}.video-heading .eyebrow{margin:0 0 5px;font-size:10px}.video-heading h2{font-size:16px}.muted{font-size:11px;color:var(--muted)}.video-frame{aspect-ratio:16/9;background:#e6e9e3;border-radius:10px;overflow:hidden}.video-frame iframe{width:100%;height:100%;border:0;display:block}
.calculator{position:sticky;top:24px;background:#e9eee7;border:1px solid #d6e0d5;border-radius:var(--radius);padding:22px}.calculator-heading{display:flex;align-items:center;justify-content:space-between}.calculator-heading .eyebrow{font-size:9px;margin-bottom:5px}.calculator-heading h2{font-size:19px}.calculator-note{font-size:11px;margin:12px 0 16px;color:#657668}.calculator-display{width:100%;border:1px solid #cbd8c8;border-radius:9px;background:#fbfcf7;padding:18px 12px;text-align:right;font-size:24px;font-variant-numeric:tabular-nums;color:#203b32;outline-offset:3px}.calculator-result{min-height:24px;text-align:right;font-size:11px;color:#657668;margin:9px 2px 13px;overflow-wrap:anywhere}.calculator-keys{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}.calculator-keys button{background:white;border:1px solid #d1dacf;border-radius:9px;min-height:49px;padding:8px;font-size:19px;color:#314c40;box-shadow:0 2px 0 #d8e0d4}.calculator-keys button:active{transform:translateY(2px);box-shadow:none}.calculator-keys .operator{background:#d6e2d5}.calculator-keys .utility{background:#edf2e8;font-size:16px}.calculator-keys .equals{background:var(--green);border-color:var(--green);color:white}.keyboard-note{font-size:10px;color:#6d7d70;margin:17px 0 0;line-height:1.8}.close-button{display:none}.page-footer{font-size:10px;line-height:1.8;color:#8a948b;padding:30px 0 0}.page-footer span{float:right}.mobile-calculator-button,.calculator-backdrop{display:none}.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}@keyframes arrive{from{opacity:0;transform:translateY(7px)}to{opacity:1;transform:translateY(0)}}
@media(max-width:900px){.page-shell{padding:28px 22px 95px;max-width:760px}.workspace{display:block}.page-header{margin-bottom:24px}.calculator{display:none}.calculator.open{display:block;position:fixed;z-index:40;top:auto;bottom:0;left:50%;transform:translateX(-50%);width:min(100%,430px);max-height:90dvh;overflow-y:auto;border-radius:22px 22px 0 0;padding:20px 24px calc(24px + env(safe-area-inset-bottom));box-shadow:0 -10px 60px #17312c30}.calculator.open .calculator-keys button{min-height:48px}.calculator-backdrop:not([hidden]){display:block;position:fixed;inset:0;background:#152c2870;border:0;z-index:35}.close-button{display:grid;place-items:center;width:38px;height:38px;border:1px solid #becfbd;border-radius:50%;font-size:26px;line-height:1;background:transparent;color:var(--green)}.mobile-calculator-button{display:flex;align-items:center;gap:12px;position:fixed;z-index:30;bottom:calc(18px + env(safe-area-inset-bottom));right:20px;background:var(--green);color:white;border:1px solid #396c61;border-radius:30px;box-shadow:0 5px 20px #1d39332a;padding:14px 19px;min-height:48px;font-weight:bold;font-size:13px}.mobile-calculator-button>span{font-size:11px;letter-spacing:2px;opacity:.75}.question-card{padding:28px}.page-footer span{float:none;display:block}.modal-open{overflow:hidden}.modal-open .mobile-calculator-button{visibility:hidden}.keyboard-note{display:none}.calculator-note{margin:8px 0 10px}}
@media(max-width:480px){.page-shell{padding:25px 16px 100px}.page-header{gap:8px}.eyebrow{font-size:10px}.eyebrow span{margin-left:7px;padding-left:8px}h1{font-size:24px}.intro{font-size:12px;line-height:1.9;max-width:280px}.text-button{font-size:11px}.question-card{padding:25px 20px;border-radius:16px}.question-title{font-size:19px}.question-description{font-size:12px}.question-label{font-size:10px}.option{font-size:14px;padding:14px 12px;gap:11px}.option-letter{width:26px;height:26px}.steps{gap:5px}.step-button{height:32px;font-size:11px;border-radius:7px}.formula{flex-wrap:wrap;gap:9px;padding:20px 9px}.formula-label{font-size:12px}.formula-equals{font-size:20px}.fraction{min-width:163px;font-size:17px}.formula input{width:128px;font-size:16px}.formula input.numeric{width:96px}.primary-button,.secondary-button{font-size:12px;padding:12px 14px}.lesson-actions{gap:8px}.data-table th,.data-table td{padding:10px 9px}.data-table{font-size:12px}.final-options{gap:8px}.final-options .option{gap:8px}.video-card{padding:20px}.video-heading h2{font-size:14px}.video-heading .muted{display:none}.completion{padding:18px}.completion-result{font-size:19px!important}}
/* Minimal chrome: circle steps connected by arrows, without visible numbering. */
.page-header{align-items:center;margin-bottom:22px}.page-header>.eyebrow{margin:0}.text-button{font-size:25px;line-height:1;padding:5px 9px;min-width:40px;min-height:40px}.steps{display:flex;align-items:center;gap:0}.steps li{display:flex;align-items:center;flex:1;min-width:0}.steps li:last-child{flex:0 0 auto}.steps li:not(:last-child)::after{content:"";flex:1;height:1px;background:#b8c9bf;margin:0 9px;clip-path:polygon(0 40%,calc(100% - 5px) 40%,calc(100% - 5px) 0,100% 50%,calc(100% - 5px) 100%,calc(100% - 5px) 60%,0 60%);min-height:7px}.step-button{flex:0 0 32px;width:32px;height:32px;border-radius:50%;font-size:12px;display:grid;place-items:center}.step-button.current{box-shadow:0 0 0 4px #1b514e14}.lesson-actions>button{font-size:22px;min-width:54px;padding:8px 18px}.calculator-heading{margin-bottom:16px}.question-description{display:none}
@media(max-width:480px){.steps li:not(:last-child)::after{margin:0 4px}.step-button{flex-basis:26px;width:26px;height:26px;border-radius:50%;font-size:10px}.page-header>.eyebrow{font-size:10px;letter-spacing:.03em}.page-header{gap:4px}.lesson-actions>button{font-size:22px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}

.formula-label{font-size:20px;font-weight:bold;line-height:1.5;white-space:nowrap}.formula{flex-wrap:wrap}@media(max-width:480px){.formula-label{font-size:18px}}
.formula .formula-expression{white-space:normal;overflow-wrap:anywhere;max-width:100%;line-height:1.8}.formula-suffix{font-size:20px;white-space:nowrap}.table-caption{font-size:18px;margin:18px 0 8px}.data-table:has(th:nth-child(5)){min-width:640px}
.formula-label{max-width:100%;white-space:normal;overflow-wrap:anywhere}.story-scenes:has(li:nth-child(4)){grid-template-columns:repeat(2,minmax(0,1fr))}

.comparison-wrap{max-width:100%}.comparison-table{table-layout:fixed}.comparison-table th:first-child{width:14%}.comparison-table td{text-align:right}.comparison-table td.relevant{background:#e1efe3;color:var(--green);font-weight:bold}.binary-options{grid-template-columns:1fr 1fr}.binary-options .option{justify-content:center}.comparison-formula{font-size:22px}.comparison-formula strong{white-space:nowrap}@media(max-width:480px){.comparison-table{font-size:11px}.comparison-table th,.comparison-table td{padding:10px 4px;overflow-wrap:anywhere}.comparison-table thead{font-size:10px}.comparison-formula{font-size:20px}}

.source-card{background:#f8faf6;border:1px solid var(--line);border-radius:var(--radius);padding:24px 28px;margin-bottom:24px}.panel-label{font-size:12px;font-weight:bold;color:var(--green);margin:0 0 16px;letter-spacing:.04em;line-height:1.5}.source-card .source{margin:0 0 12px}.source-card .original-question{margin:0 0 16px}.source-card .data-table-wrap{margin:16px auto 0}.source-card .data-table-wrap .data-table{background:#fff}.source-card .data-table tr.relevant{background:#edf5ed}@media(max-width:480px){.source-card{padding:20px 16px;border-radius:16px;margin-bottom:20px}}

.source-card{margin-top:24px;margin-bottom:0}

/* Shared cell highlights, inline reference table and numeric headings. */
.data-table .numeric-column{text-align:right}.data-table [data-cell].relevant{background:#e1efe3;color:var(--green);font-weight:bold}.step-table{margin:18px 0 26px}.step-table .data-table-wrap{margin:0 auto}.data-table thead th{vertical-align:bottom}.calculator-heading h2{margin:0}

/* Reading size: lesson content takes priority over compact presentation. */
.learning-sidebar{position:sticky;top:24px;max-height:calc(100dvh - 48px);overflow-y:auto;min-width:0}
.learning-sidebar .calculator{position:static}
.lesson-menu{margin-top:18px;padding:20px;background:var(--paper);border:1px solid var(--line);border-radius:var(--radius)}
.lesson-menu ol{list-style:none;margin:0;padding:0;display:grid;gap:6px}
.lesson-menu a{display:flex;align-items:baseline;gap:10px;padding:11px 9px;border-radius:8px;color:var(--ink);font-size:14px;line-height:1.7;text-decoration:none}
.lesson-menu a:hover{background:var(--green-light)}
.lesson-menu a[aria-current="page"]{background:var(--green-light);color:var(--green);font-weight:bold}
.lesson-number{flex:none;font-variant-numeric:tabular-nums;color:var(--muted)}
.completion-actions{display:flex;flex-wrap:wrap;align-items:center;gap:12px;margin-top:18px}
.completion-actions a{text-decoration:none}
.submit-button{width:180px;min-height:48px}
.lesson-actions #next{width:180px;min-height:48px;font-size:14px}
.completion-actions .next-lesson{display:flex;justify-content:space-between;align-items:center;flex:0 0 100%;width:100%;min-height:104px;padding:22px 26px;border-radius:14px;text-align:left;gap:18px}
.next-lesson-label{display:block;font-size:28px;font-weight:bold;line-height:1.4}
.next-lesson-title{display:block;font-size:15px;font-weight:normal;line-height:1.6;margin-top:6px}
.next-lesson-arrow{font-size:36px;flex:none}
@media(max-width:480px){.completion-actions .next-lesson{padding:20px;min-height:100px}.next-lesson-label{font-size:25px}.next-lesson-title{font-size:14px}}
@media(max-width:900px){.learning-sidebar{position:static;max-height:none;overflow:visible}.learning-sidebar .calculator.open{position:fixed}.lesson-menu{margin-top:24px}}
.page-header .text-button{font-size:14px;font-weight:bold;padding:9px 13px;border:1px solid var(--line);border-radius:10px;background:#fff;min-height:42px}
.question-card.final-challenge{background:#fff8ed;border-color:#d4ad76}
.final-challenge>.panel-label{color:#94571d}
.final-challenge .question-title{color:#643c20}
.final-challenge .data-table thead{background:#f1e4d0;color:#725235}
.final-challenge .option{border-color:#dfc8a8;background:#fffdf9}
.final-challenge .option:hover:not(:disabled){background:#fff0d9;border-color:#b98039}
.final-challenge .option-letter{background:#f2e3cd;color:#875820}
.final-challenge .option.correct{background:#f5dfb8;border-color:#b8792e}
.final-challenge .option.correct .option-letter{background:var(--green);color:white}
.final-challenge .option.incorrect{background:#fff0e6;border-color:#c78c62}
.question-title{font-size:28px;line-height:1.65}
.option{font-size:20px;min-height:66px}
.option-letter{font-size:15px}
.step-table .data-table,.step-table .comparison-table{font-size:18px;line-height:1.65}
.step-table .data-table th,.step-table .data-table td{padding:12px 10px}
.step-table .data-table thead{font-size:15px}
.table-unit,.hint-button,.input-guide{font-size:14px}
.step-table .table-unit{margin-bottom:8px}
.feedback,.hint{font-size:16px}
.feedback strong{font-size:18px}
.calculated-values{font-size:16px}
.formula-label{font-size:22px}
.fraction{font-size:24px}
.input-unit{font-size:17px}
.original-question{font-size:17px}
.source-card .data-table{font-size:16px}
.source-card .data-table thead{font-size:14px}
.data-table-wrap{overflow-x:auto}
.story-guide{margin:0 0 24px;padding-bottom:20px;border-bottom:1px solid var(--line);outline:none}
.story-goal{font-size:15px;line-height:1.8;color:var(--muted);margin:0 0 14px}
.story-scenes{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:7px;list-style:none;margin:0;padding:0}
.story-scenes li{padding:9px 6px;background:var(--green-light);color:var(--muted);border-radius:8px;text-align:center;font-size:13px;line-height:1.5}
.story-scenes li.current{background:var(--green);color:#fffaf2;font-weight:bold}
.scene-purpose{margin:12px 0 0;padding-left:10px;border-left:3px solid var(--green);color:var(--green);font-size:15px;font-weight:bold;line-height:1.7}
@media(max-width:480px){.story-goal{font-size:13px}.story-scenes li{font-size:12px}.scene-purpose{font-size:14px}}
.learning-summary{padding:22px;background:#fbefd9;border:1px solid #dfc49b;border-radius:14px;margin-bottom:30px}
.learning-summary h2{font-size:20px;color:#815026;outline:none}
.learning-summary ul{list-style:none;margin:16px 0 0;padding:0;display:grid;gap:16px}
.learning-summary li{padding-bottom:14px;border-bottom:1px solid #e6cfaf}
.learning-summary li:last-child{border-bottom:0;padding-bottom:0}
.learning-summary .summary-question{font-size:14px;color:#876950;margin:0 0 5px}
.learning-summary strong{font-size:19px;color:#704118}
.learning-summary .summary-explanation{font-size:15px;line-height:1.8;margin:5px 0 0}
.learning-summary .formula{background:#fff8ed;margin:18px 0}
.completion-actions .next-lesson:disabled{opacity:1;background:#e9d5b6;border-color:#d2b48b;color:#765736;cursor:default}
/* Every surface switches with the final challenge, including the sidebar. */
body.challenge-mode{--bg:#f6ecdf;--paper:#fffaf2;--ink:#593b27;--muted:#87674d;--line:#e1c8a7;--green:#955923;--green-light:#f5e4ca;--amber:#9c601e;background:var(--bg);color:var(--ink);min-height:100dvh}
.challenge-mode .step-button{background:#f1e2cf;color:#a27c55;border-color:#ddc6a8}
.challenge-mode .step-button.complete{background:#f0dabc;color:#955923;border-color:#d5b185}
.challenge-mode .step-button.current,.challenge-mode .step-button.current.complete{background:#955923;color:#fffaf3;border-color:#955923;box-shadow:0 0 0 4px #9559231a}
.challenge-mode .steps li:not(:last-child)::after{background:#c8a47d}
.challenge-mode .eyebrow span{border-color:#d9bd9a}
.challenge-mode .page-header .text-button,.challenge-mode .secondary-button{background:#fffaf2;color:#87674d;border-color:#d8bc98}
.challenge-mode .primary-button:hover:not(:disabled){background:#78411c}
.challenge-mode .lesson-actions{border-color:#ead6bd}
.challenge-mode .feedback{background:#f8e6c9;color:#71451f;border-color:#b47c39}
.challenge-mode .feedback.wrong{background:#fff0df;color:#8b4e26;border-color:#c4884d}
.challenge-mode .completion{background:#f7e5c9;border-color:#d6af79}
.challenge-mode .option.correct{background:#f5dfb8;border-color:#b8792e}
.challenge-mode .option.correct .option-letter{background:#955923;color:#fffaf2}
.challenge-mode .option.unselected{opacity:.65}
.challenge-mode .data-table thead{background:#f1e2cb;color:#805d38}
.challenge-mode .data-table th,.challenge-mode .data-table td{border-color:#e6d2b6}
.challenge-mode .numerator{border-color:#b68b57}
.challenge-mode .formula{background:#fff4e3}
.challenge-mode .calculator{background:#f0dfc6;border-color:#d9b98f}
.challenge-mode .calculator-display{background:#fffaf1;color:#603d21;border-color:#d6b58d}
.challenge-mode .calculator-result{color:#856348}
.challenge-mode .calculator-keys button{background:#fffaf2;color:#704b29;border-color:#d6b78f;box-shadow:0 2px 0 #d8bd99}
.challenge-mode .calculator-keys .utility{background:#f6ead7}
.challenge-mode .calculator-keys .operator{background:#e6caa2}
.challenge-mode .calculator-keys .equals{background:#955923;color:#fffaf2;border-color:#955923}
.challenge-mode .calculator.open{box-shadow:0 -10px 60px #69421d30}
.challenge-mode .close-button{border-color:#c9a371;color:#955923}
.challenge-mode .calculator-backdrop{background:#5b361c70}
.challenge-mode .mobile-calculator-button{background:#955923;border-color:#a56a35;box-shadow:0 5px 20px #76451e2a}
.challenge-mode .page-footer{color:#927154}
@media(max-width:360px){#steps:has(li:nth-child(13)) .step-button{flex-basis:20px;width:20px;height:20px}}
/* Mobile calculator gets its own bottom space instead of covering the lesson. */
@media(max-width:900px){
  html,body{height:100dvh;overflow:hidden;overscroll-behavior:none}
  #quiz-app{height:100dvh;overflow:hidden;display:flex;flex-direction:column}
  #quiz-app>.page-shell{flex:1;min-height:0;width:100%;overflow-y:auto;overscroll-behavior-y:contain;padding-bottom:24px;scroll-padding-bottom:16px}
  .mobile-calculator-button{position:static;flex:none;align-self:flex-end;margin:12px 20px calc(12px + env(safe-area-inset-bottom))}
  .modal-open #quiz-app>.page-shell{overflow:hidden}
}
@media(max-width:480px){
  .learning-summary{padding:18px}
  .steps .step-button{flex-basis:24px;width:24px;height:24px;font-size:10px}
  .steps:has(li:nth-child(12)) .step-button{flex-basis:22px;width:22px;height:22px}
  .steps li:not(:last-child)::after{margin:0 1px}
  .question-title{font-size:23px}
  .option{font-size:18px}
  .step-table .data-table,.step-table .comparison-table{font-size:16px}
  .step-table .data-table thead{font-size:14px}
  .step-table .data-table th,.step-table .data-table td{padding:11px 8px}
  .comparison-table{min-width:540px}
  .formula-label{font-size:20px}
  .fraction{font-size:22px}
  .original-question{font-size:16px}
}

/* 整理用の表（data.workTable がある教材だけ） */
.work-table-wrap{margin:0 0 18px;padding:12px 14px;border:1px dashed #9bb8a5;border-radius:12px;background:#fbfdfb}
.work-table-title{margin:0 0 8px;font-size:12px;font-weight:bold;color:var(--green)}
.work-table-title span{margin-left:10px;font-weight:normal;color:var(--muted)}
.work-table{width:100%;font-size:14px}
.work-table td{position:relative;text-align:right;min-width:7em;height:2.4em}
.work-table td.given{color:#333}
.work-table td.filled{background:#e3f1e6;color:var(--green);font-weight:bold}
.work-table td.unknown{color:#b0460c;font-weight:bold;font-size:18px}
.work-table td.target{outline:3px solid #f0b400;outline-offset:-3px;background:#fff8dc}
.here-mark{position:absolute;left:6px;top:50%;transform:translateY(-50%);font-size:10px;font-weight:bold;color:#fff;background:#e09b00;border-radius:999px;padding:2px 7px}
@media(max-width:480px){.work-table{font-size:12px}.work-table td{min-width:0}.here-mark{font-size:9px;padding:1px 5px;left:3px}}

/* 最初の画面（問題文と案内） */
.intro-lead{margin:22px 0 0;padding:14px 16px;border-radius:12px;background:var(--green-light);color:var(--green);font-weight:bold;font-size:17px;text-align:center;line-height:1.6}
/* 解説動画（動画がある問題だけ）：上にジャンプボタン、ページの一番下に横長の動画 */
.video-jump{display:inline-flex;align-items:center;gap:6px;margin:0 0 12px;padding:9px 16px;border-radius:999px;background:#c4302b;color:#fff;font-weight:bold;font-size:14px;text-decoration:none;box-shadow:0 2px 6px #c4302b33}
.video-jump:hover{background:#a82722}
.video-jump[hidden],.video-section[hidden]{display:none}
.video-section{margin:40px auto 0;padding:20px 20px 18px;max-width:860px;background:var(--paper);border:1px solid var(--line);border-radius:var(--radius);text-align:center;scroll-margin-top:16px}
.video-section .panel-label{text-align:left}
.video-frame-wide{position:relative;width:100%;aspect-ratio:16/9;border-radius:12px;overflow:hidden;background:#000}
.video-frame-wide iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.video-back{margin-top:14px;padding:7px 14px;border-radius:999px;border:1px solid var(--line);background:transparent;color:inherit;font-size:13px;cursor:pointer}
@media(max-width:480px){.video-section{padding:14px 10px 14px}}
/* カットの行き先（step.dest がある問題だけ） */
.cut-dest{margin:0 0 10px;padding:8px 12px;border-left:4px solid #e09b00;background:#fff8e6;color:#7a5200;font-size:13px;font-weight:bold;line-height:1.6;border-radius:0 8px 8px 0}
/* ミッション（シーン）表示 2026-11-06 */
.mission-guide{margin:0 0 18px;padding:14px 16px;border-radius:14px;background:var(--green);color:#fffaf2;outline:none}
.mission-top{display:flex;align-items:center;justify-content:space-between;gap:10px}
.mission-label{font-size:12px;font-weight:bold;letter-spacing:.08em;opacity:.85}
.mission-list{display:flex;gap:5px;list-style:none;margin:0;padding:0}
.mission-list li{width:22px;height:22px;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:11px;font-weight:bold;background:#ffffff26;color:#fffaf2}
.mission-list li.cleared{background:#f0b400;color:#3b2a00}
.mission-list li.current{background:#fffaf2;color:var(--green)}
.mission-title{margin:8px 0 10px;font-size:21px;font-weight:bold;line-height:1.45}
.mission-dots{display:flex;align-items:center;gap:6px}
.mission-dot{width:12px;height:12px;border-radius:50%;border:2px solid #fffaf2aa}
.mission-dot.done{background:#f0b400;border-color:#f0b400}
.mission-dot.now{border-color:#fffaf2;box-shadow:0 0 0 3px #ffffff40}
.mission-count{margin-left:6px;font-size:12px;opacity:.85}
.mission-clear{margin-top:10px;padding:10px 12px;border-radius:10px;background:#f0b400;color:#3b2a00}
.mission-clear b{display:block;font-size:16px;letter-spacing:.04em}
.mission-clear span{display:block;font-size:13px;margin-top:2px}
.challenge-mode .mission-guide{background:#955923}
@media(max-width:480px){.mission-title{font-size:18px}}
/* ミッションごとの色（帯ははっきり、背景はうっすら） 2026-11-06 */
body{transition:background-color .5s ease}
.mission-guide{background:var(--mission,var(--green));transition:background-color .5s ease}
body[data-mission="0"]{--mission:#1e6b3a;--bg:#f1f7f2;background:var(--bg)}
body[data-mission="1"]{--mission:#1f5a8a;--bg:#eef4fa;background:var(--bg)}
body[data-mission="2"]{--mission:#5b3a86;--bg:#f4f0fa;background:var(--bg)}
body[data-mission="3"]{--mission:#7a4e1e;--bg:#f8f2ea;background:var(--bg)}
body[data-mission="4"]{--mission:#23305c;--bg:#eff1f7;background:var(--bg)}
body[data-mission]{min-height:100vh}
/* スマホの電卓ボタンを左下へ。見た目も白地＋枠線にして「答えを確かめる」と区別する 2026-11-06 */
@media(max-width:900px){
  .mobile-calculator-button{align-self:flex-start;left:20px;right:auto;background:var(--paper);color:var(--green);border:2px solid var(--green);box-shadow:0 3px 12px #1d39331a}
  .mobile-calculator-button>span{opacity:.9}
  .challenge-mode .mobile-calculator-button{background:#fffaf2;color:#955923;border-color:#955923;box-shadow:0 3px 12px #76451e1a}
}
/* 「答えを確かめる」と「次へ」を分ける 2026-11-06 */
.check-button{margin-top:16px;min-width:180px}
.lesson-actions #next:disabled{background:#c9d1cc;border-color:#c9d1cc;color:#fff;cursor:not-allowed;opacity:1;box-shadow:none}
.challenge-mode .lesson-actions #next:disabled{background:#e2d2bd;border-color:#e2d2bd}
/* 列が4つ以上の表は枠を広げ、左端の列が隠れないようにする 2026-11-06 */
.data-table-wrap:has(thead th:nth-child(4)){max-width:100%}
.data-table-wrap:has(thead th:nth-child(5)) .data-table th,.data-table-wrap:has(thead th:nth-child(5)) .data-table td{padding-left:8px;padding-right:8px}
.data-table-wrap{overflow-x:auto}
/* 解説の下に操作ボタン */
#question-card > .feedback{margin-top:18px}
/* 確認用ボタン（本番では出ない） */
.review-skip{margin-left:auto;margin-right:10px;padding:8px 12px;border-radius:999px;border:1px dashed #b0460c;background:#fff4ec;color:#b0460c;font-size:12px;font-weight:bold;cursor:pointer}
.lesson-actions{flex-wrap:wrap;gap:8px}
/* 図（step.figure がある問いだけ） */
.step-figure{margin:6px 0 18px;padding:10px;border:1px solid var(--line);border-radius:14px;background:#fff}
.step-figure svg{display:block;width:100%;height:auto}
/* X に途中経過・クリアを投稿 2026-11-06 */
.share-row{display:flex;align-items:center;gap:12px;flex-wrap:wrap;margin:0 0 12px}
.share-x{display:inline-flex;align-items:center;gap:6px;padding:7px 14px;border-radius:999px;border:1px solid #111;background:#111;color:#fff;font-size:13px;font-weight:bold;cursor:pointer}
.share-x:disabled{background:#c9d1cc;border-color:#c9d1cc;cursor:not-allowed}
.share-x span{font-size:15px}
.share-note{font-size:12px;color:var(--muted);margin:0}
.share-clear{margin-top:16px;display:flex;flex-direction:column;align-items:flex-start;gap:6px}
.share-x-big{padding:11px 20px;font-size:15px}
/* アプリの名前 */
.eyebrow .app-title{display:block;font-size:15px;color:var(--green);letter-spacing:.02em;margin-bottom:2px}
.eyebrow a.app-title{font-weight:700;text-decoration:none}.eyebrow a.app-title:hover{text-decoration:underline}

/* 最初の画面の選択肢（見せるだけ） */
.intro-choices{list-style:none;margin:18px 0 0;padding:0;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px 14px}.intro-choices-long{grid-template-columns:1fr}
.intro-choices li{display:flex;gap:10px;align-items:baseline;padding:8px 12px;border:1px solid var(--line);border-radius:10px;background:var(--paper);font-size:16px;line-height:1.6}
.intro-choice-mark{flex:none;font-weight:bold;color:var(--green)}

/* スマホの電卓ボタンをヘッダーへ。ヘッダーは上に貼り付けて、スクロールしても電卓と「最初から」が押せる 2026-11-06 */
.header-actions{display:flex;align-items:center;gap:8px;flex:none}
@media(max-width:900px){
  .page-header{position:sticky;top:-28px;z-index:40;margin:-28px -22px 22px;padding:10px 22px;background:var(--bg,#f4f4ef);border-bottom:1px solid var(--line)}
  .page-header .mobile-calculator-button{position:static;margin:0;align-self:auto;gap:6px;padding:8px 12px;min-height:42px;font-size:14px;font-weight:bold;border-radius:10px;box-shadow:none}
  .page-header .mobile-calculator-button>span{font-size:10px;letter-spacing:1px}
}
@media(max-width:480px){.page-header{top:-25px;margin:-25px -16px 16px;padding:8px 16px;gap:8px}.page-header .mobile-calculator-button>span{display:none}.page-header>.eyebrow{min-width:0;line-height:1.4}.page-header .app-title{white-space:nowrap;overflow:hidden;text-overflow:ellipsis;font-size:13px;margin-bottom:1px}.page-header .header-actions{gap:6px}.page-header .header-actions>*{min-height:38px;padding:6px 10px;font-size:13px}}

/* 最初の画面：「正解した人の思考を1つ1つ辿ってみよう →」を始めるボタンにする 2026-11-07 */
.intro-start{display:block;width:100%;margin:22px 0 0;padding:16px 18px;font-size:17px;line-height:1.6;white-space:normal;text-align:center}
.lesson-actions.intro-actions:not(:has(#review-skip)){display:none}

/* X の投稿の埋め込み（最後のステップとトップページ） */
.x-post{max-width:550px;margin:18px auto 0}.x-post-link{display:inline-block;padding:10px 16px;border-radius:999px;background:#111;color:#fff;font-weight:bold;text-decoration:none}