:root{--bg:#fafafd;--surface:#ffffff;--ink:#1f1f28;--muted:#686272;--line:#dad7e3;--primary:#7b5fe1;--depth:#6246c4;--soft:#eae3f6;--accent:#9c78c2;font-family:Inter,"Noto Sans JP","Hiragino Sans","Yu Gothic",system-ui,sans-serif;color:var(--ink);background:var(--bg);font-synthesis:none}*{box-sizing:border-box}body{margin:0}button,input,select{font:inherit}button,a,input{touch-action:manipulation}button,a{cursor:pointer;-webkit-tap-highlight-color:transparent}a{color:inherit;text-decoration:none}button{color:inherit;border:0;min-height:44px}button:disabled{opacity:.5;cursor:default}button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid var(--accent);outline-offset:4px}button:not(:disabled):hover{filter:brightness(.95)}h1,h2,h3,p{margin:0}[hidden]{display:none!important}.wrap{width:min(92%,1200px);margin:auto}.site-header{min-height:94px;display:flex;align-items:center;gap:34px;border-bottom:1px solid var(--line)}.brand{display:flex;align-items:center;gap:12px;font-size:19px;font-weight:700;letter-spacing:.08em}.brand img{flex-shrink:0}.header-note{font-size:12px;letter-spacing:.14em;color:var(--muted)}.sample-label{margin-left:auto;font-size:13px;display:flex;align-items:center;gap:13px}.sample-label small{font-size:10px;border:1px solid #dad7e3;color:var(--muted);padding:5px 9px;border-radius:3px}.eyebrow{font-size:11px;letter-spacing:.17em;color:var(--primary);font-weight:600}.intro{position:relative;padding:45px 0 39px;display:flex;align-items:center;justify-content:space-between;gap:20px}.intro h1{font-weight:600;font-size:clamp(32px,4vw,44px);letter-spacing:.1em;margin:12px 0 15px;line-height:1.5}.intro-copy{font-size:15px;line-height:1.9;color:var(--muted)}.intro-art{width:280px;height:156px;margin-right:34px;flex-shrink:0}.section-line{border-top:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;padding:21px 0;gap:15px}.section-line 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var(--line);margin-top:22px;padding-top:13px;display:flex;justify-content:space-between;align-items:center;width:100%;font-size:12px;color:var(--depth)}.theme-bottom b{font-size:20px;font-weight:400}.guide{display:flex;gap:30px;align-items:center;padding:24px 0 35px;font-size:13px;color:var(--muted)}.guide strong{color:var(--ink);font-weight:500}.guide span span{font-size:12px;color:var(--primary);margin-right:7px}.guide .separator{color:#9c78c2}.workspace-nav{display:flex;justify-content:space-between;align-items:center;padding:17px 0;font-size:13px;color:var(--muted)}.text-button{background:transparent;padding:8px 0;color:var(--muted);font-size:13px}.workspace-title{display:flex;justify-content:space-between;align-items:center;padding:12px 0 27px;gap:20px}.workspace-title h1{font-size:30px;letter-spacing:.06em;font-weight:600;margin:10px 0}.workspace-title p:last-child{color:var(--muted);font-size:14px;line-height:1.8}.progress{display:flex;gap:7px;flex-shrink:0}.progress i{width:26px;height:3px;background:#e5deef}.progress i.done{background:#b69aef}.progress i.active{background:var(--depth)}.practice-grid{display:grid;grid-template-columns:minmax(0,1.8fr) minmax(275px,1fr);gap:32px;align-items:start;margin-bottom:44px}.paper{background:var(--surface);border-radius:4px;overflow:hidden;min-width:0}.paper-top{display:flex;justify-content:space-between;font-size:11px;letter-spacing:.08em;color:var(--muted);padding:19px 26px;border-bottom:1px solid var(--line)}.problem-zone{padding:30px 34px 20px;min-height:180px;background-image:linear-gradient(#dad7e355 1px,transparent 1px),linear-gradient(90deg,#dad7e355 1px,transparent 1px);background-size:28px 28px}.problem-label{font-size:12px;color:var(--muted);margin-bottom:21px}.problem{font-size:clamp(24px,3.2vw,38px);font-weight:500;line-height:1.6;letter-spacing:.04em;overflow-wrap:anywhere}.problem.words{font-size:clamp(20px,2.4vw,27px)}.answer-area{padding:23px 34px 27px}.answer-label{font-size:13px;display:block;margin-bottom:12px}.answer-row{display:flex;gap:13px;align-items:center}.answer-input{width:100%;min-width:0;height:54px;background:white;border:1px solid #b9adce;border-radius:5px;color:var(--depth);font-size:25px;padding:10px 15px;font-variant-numeric:tabular-nums}.answer-input:disabled{background:#f2f0f7}.primary{background:var(--depth);color:white;border-radius:28px;padding:13px 26px;font-size:14px;min-height:49px;white-space:nowrap}.outline{background:transparent;border:1px solid #b69aef;color:var(--depth);border-radius:28px;padding:12px 23px;font-size:14px}.fraction-input{display:flex;align-items:center;gap:12px;min-width:0;flex:1}.fraction-input span{font-size:26px;color:var(--muted)}.input-note{font-size:11px;color:var(--muted);margin:10px 0 0;line-height:1.7}.feedback{font-size:14px;line-height:1.8;padding:15px 17px;margin:17px 0 0;background:#f2f0f7;color:var(--depth);border-left:2px solid var(--primary)}.feedback.retry{background:#f2f0f7;border-color:var(--accent);color:#624775}.next-actions{display:flex;gap:10px;flex-wrap:wrap;margin-top:19px}.choices{display:flex;gap:10px;flex-wrap:wrap}.choice{border:1px solid #b9adce;background:white;border-radius:6px;padding:13px 19px;flex:1;min-width:100px}.choice[aria-pressed=true]{background:var(--soft);border-color:var(--primary);color:var(--depth)}.choice-submit{margin-top:17px}.help{background:#f2f0f7;border-radius:10px;padding:26px}.help-top{display:flex;justify-content:space-between;align-items:center;gap:10px;margin-bottom:18px}.help-top h2{font-size:17px;font-weight:600}.help-top span{font-family:Georgia,serif;color:var(--primary);font-size:24px}.help>p{font-size:14px;color:var(--muted);line-height:1.9}.help .outline{width:100%;margin-top:22px}.hints{list-style:none;padding:0;margin:0}.hints li{border-top:1px solid #dad7e3;padding:18px 0 0;margin-top:18px;font-size:14px;line-height:1.9}.hints li small{display:block;font-size:10px;letter-spacing:.12em;color:var(--primary);margin-bottom:6px}.help .text-button{width:100%;margin-top:7px}.side-note{font-size:12px;color:var(--muted);line-height:1.9;padding:19px 9px}.finish{max-width:650px;margin:68px auto 75px;text-align:center}.finish-mark{display:grid;place-items:center;width:88px;height:88px;border-radius:50%;border:1px solid #b69aef;background:#f2f0f7;margin:0 auto 27px;font-family:Georgia,serif;font-size:40px;font-style:italic;color:var(--depth)}.finish h1{font-size:30px;font-weight:500;letter-spacing:.06em;margin:17px 0}.finish p{color:var(--muted);line-height:2;font-size:15px}.finish-actions{display:flex;justify-content:center;gap:12px;flex-wrap:wrap;margin:29px 0}.finish .finish-note{font-size:12px}footer{display:flex;justify-content:space-between;gap:20px;border-top:1px solid var(--line);padding:23px 0 30px;font-size:11px;line-height:1.8;color:var(--muted)}.footer-note{margin-left:12px}
@media(min-width:1450px){.intro{padding-top:60px;padding-bottom:45px}.theme{padding:30px}.catalog{gap:22px}}
@media(max-width:900px){.header-note{display:none}.catalog{grid-template-columns:repeat(2,minmax(0,1fr))}.intro-art{margin-right:0;width:215px}.practice-grid{grid-template-columns:minmax(0,1.5fr) minmax(240px,1fr);gap:20px}.answer-row{flex-wrap:wrap}.answer-row>.primary{width:100%}.answer-area,.problem-zone{padding-left:24px;padding-right:24px}.guide{gap:16px;font-size:12px}.guide strong{display:none}}
@media(max-width:600px){.site-header{min-height:77px;gap:12px}.brand{font-size:16px;gap:7px}.brand img{width:29px;height:37px}.sample-label{font-size:10px;gap:5px}.sample-label small{font-size:9px;padding:4px 6px}.intro{padding:30px 0}.intro h1{font-size:32px}.intro-copy{font-size:13px}.intro-art{position:absolute;right:0;top:30px;width:96px;height:85px;opacity:.55}.intro .eyebrow{font-size:9px}.catalog{gap:11px}.theme{padding:17px 16px 14px}.theme h3{font-size:17px;margin-top:10px}.theme p{font-size:12px;min-height:43px}.theme-symbol{font-size:31px;height:40px}.theme-bottom{margin-top:16px;font-size:11px}.theme-number{font-size:11px}.section-line h2{font-size:16px}.section-line span{font-size:10px}.guide{flex-wrap:wrap;justify-content:center;gap:10px;padding:24px 0 29px;font-size:11px}.workspace-title h1{font-size:25px}.workspace-title{gap:10px;align-items:flex-start;padding-bottom:20px}.workspace-title p:last-child{font-size:12px}.progress{gap:4px;margin-top:13px}.progress i{width:15px}.practice-grid{grid-template-columns:1fr;gap:21px}.paper-top{padding:16px 21px}.problem-zone{min-height:157px;padding:24px 21px}.problem{font-size:31px}.problem.words{font-size:23px}.answer-area{padding:21px}.answer-row{flex-wrap:nowrap}.answer-row>.primary{width:auto;font-size:13px;padding:13px 18px}.answer-input{height:51px;font-size:23px}.help{padding:23px}.side-note{padding:14px 5px 0}.finish{margin:45px auto 55px}.finish h1{font-size:26px}footer{flex-direction:column;gap:7px;font-size:10px}.footer-note{margin-left:5px}}
@media(max-width:360px){.sample-label{font-size:0}.sample-label small{font-size:9px}.intro-art{display:none}.theme{padding:15px 12px}.theme h3{font-size:16px}.answer-row{flex-wrap:wrap}.answer-row>.primary{width:100%}.fraction-input{flex-basis:100%}}
.portal-back{margin-left:auto;font-size:12px;color:var(--muted);white-space:nowrap;padding:13px 0}.primary{background:var(--primary)}.theme{border-color:#ebe7f1}.theme-symbol.warm{color:var(--primary)}.help{border:1px solid #e7e0ef}.intro-art{opacity:.85}.feedback{color:#533c8a}.finish-mark{font-style:normal}.answer-input:focus{border-color:var(--primary)}@media(max-width:600px){.portal-back{font-size:11px}.theme p{min-height:65px}.brand{font-size:16px}}@media(prefers-reduced-motion:reduce){*{transition:none!important}}

.theme-training{border-color:#d7c9ef;background:#faf6ff}.theme-training .theme-symbol{font-size:31px;font-style:italic}.theme-training .theme-number{color:var(--depth)}

.notebook-footer{align-items:center}.notebook-footer nav{margin-left:auto}.notebook-switch{display:inline-flex;align-items:center;justify-content:center;gap:9px;min-height:44px;padding:9px 15px;border:1px solid #b9adce;border-radius:24px;color:#533c8a;font-size:12px;font-weight:600;line-height:1.5;text-align:center}.notebook-switch:hover{background:#f2edfa}.notebook-switch:focus-visible{outline:3px solid var(--accent);outline-offset:3px}@media(max-width:600px){.notebook-footer{align-items:stretch}.notebook-footer nav{margin-left:0}.notebook-switch{width:100%;font-size:13px}}

.file-help{max-width:640px;margin:55px auto 65px;padding:28px 30px;border:1px solid #d7c9ef;border-radius:8px;background:#fff}.file-help h1{font-size:23px;line-height:1.5;color:#533c8a}.file-help p{margin-top:14px;font-size:14px;line-height:1.9;color:#686272}@media(max-width:600px){.file-help{margin:30px auto 45px;padding:22px}.file-help h1{font-size:20px}}