.ichitasu-practice-app{--ink:#252525;--muted:#777;--line:#e6e6e6;--blue1:#91bce5;--blue2:#4f8fcb;--blue3:#1e5791;--ok:#317358;--oksoft:#edf7f1;--bad:#a84f4f;--badsoft:#fbefef;max-width:820px;margin:28px auto;padding:0;color:var(--ink);font-family:-apple-system,BlinkMacSystemFont,"Hiragino Kaku Gothic ProN","Yu Gothic",YuGothic,Meiryo,sans-serif;line-height:1.8}.ichitasu-practice-app *{box-sizing:border-box}.ichitasu-practice-app .practice-kicker{color:#777;font-size:12px;letter-spacing:.14em}.ichitasu-practice-app h2{margin:0;font-size:clamp(22px,4vw,30px);font-weight:600}.ichitasu-practice-app .intro{margin:6px 0 20px;color:#5f5f5f;font-size:14px}.ichitasu-practice-app .level-tabs{display:grid;grid-template-columns:repeat(3,1fr);gap:1px;background:var(--line);border:1px solid var(--line);margin-bottom:22px}.ichitasu-practice-app .level-tab{border:0;background:#fff;padding:12px 8px;cursor:pointer;color:#555;font-size:14px}.ichitasu-practice-app .level-tab strong{display:block;color:var(--ink);font-size:15px}.ichitasu-practice-app .level-tab.active,.ichitasu-practice-app .level-tab.active strong{color:#fff}.ichitasu-practice-app .level-tab[data-level="1"].active{background:var(--blue1)}.ichitasu-practice-app .level-tab[data-level="2"].active{background:var(--blue2)}.ichitasu-practice-app .level-tab[data-level="3"].active{background:var(--blue3)}.ichitasu-practice-app .problem-card{border:1px solid var(--line);border-top:4px solid var(--blue1);background:#fff}.ichitasu-practice-app .problem-card.level-2{border-top-color:var(--blue2)}.ichitasu-practice-app .problem-card.level-3{border-top-color:var(--blue3)}.ichitasu-practice-app .card-head{display:flex;justify-content:space-between;padding:11px 15px;border-bottom:1px solid var(--line);background:#f7faff}.ichitasu-practice-app .level-label{font-size:13px;font-weight:700}.ichitasu-practice-app .progress{font-size:12px;color:var(--muted)}.ichitasu-practice-app .problem-body{padding:20px}.ichitasu-practice-app .prompt{font-weight:700;margin:0 0 8px}.ichitasu-practice-app .math{font-family:"Times New Roman","Yu Mincho","Hiragino Mincho ProN",serif;font-size:1.18rem;text-align:center;line-height:2;margin:8px 0 16px}.ichitasu-practice-app .choices{display:grid;gap:8px}.ichitasu-practice-app .choice{width:100%;border:1px solid #d4d4d4;background:#fff;text-align:left;padding:10px 12px;cursor:pointer;font-size:15px}.ichitasu-practice-app .choice.selected{border-color:#2f6fb0;background:#edf4fb}.ichitasu-practice-app .choice.correct{border-color:var(--ok);background:var(--oksoft)}.ichitasu-practice-app .choice.wrong{border-color:var(--bad);background:var(--badsoft)}.ichitasu-practice-app .letter{display:inline-flex;width:24px;height:24px;border:1px solid #aaa;align-items:center;justify-content:center;margin-right:9px;font-size:12px}.ichitasu-practice-app .actions{display:flex;flex-wrap:wrap;gap:8px;margin-top:16px}.ichitasu-practice-app .btn{border:1px solid #2f6fb0;background:#fff;color:#1f4f82;padding:9px 14px;cursor:pointer;font-weight:700;font-size:14px}.ichitasu-practice-app .level-1 .btn.primary{background:var(--blue1);border-color:var(--blue1);color:#17324a}.ichitasu-practice-app .level-2 .btn.primary{background:var(--blue2);border-color:var(--blue2);color:#fff}.ichitasu-practice-app .level-3 .btn.primary{background:var(--blue3);border-color:var(--blue3);color:#fff}.ichitasu-practice-app .feedback{display:none;margin-top:12px;padding:9px 12px;border-left:3px solid;font-size:14px}.ichitasu-practice-app .feedback.ok{display:block;background:var(--oksoft);border-color:var(--ok);color:#2d694f}.ichitasu-practice-app .feedback.bad{display:block;background:var(--badsoft);border-color:var(--bad);color:#914646}.ichitasu-practice-app .hint-panel{display:none;margin-top:14px;padding:14px;background:#edf4fb;border-left:3px solid #2f6fb0;font-size:14px}.ichitasu-practice-app .hint-panel.show{display:block}.ichitasu-practice-app .solution-panel{display:none;margin-top:18px;border:1px solid #d8d8d8}.ichitasu-practice-app .solution-panel.show{display:block}.ichitasu-practice-app .solution-title{padding:10px 14px;background:#eef5fc;border-bottom:1px solid #d8d8d8;font-weight:700}.ichitasu-practice-app .solution-paper{padding:18px;background:repeating-linear-gradient(to bottom,#fff 0,#fff 31px,#f1f1f1 32px)}.ichitasu-practice-app .step{margin:0 0 16px;background:rgba(255,255,255,.94)}.ichitasu-practice-app .step-label{font-size:13px;font-weight:700;color:#234f7b}.ichitasu-practice-app .step-text{font-size:14px}.ichitasu-practice-app .answer-box{margin-top:14px;border:2px solid #252525;padding:9px 12px;text-align:center;font-weight:700;background:#fff}.ichitasu-practice-app .next-row{display:flex;justify-content:flex-end;margin-top:16px}@media(max-width:640px){.ichitasu-practice-app .level-tabs{grid-template-columns:1fr}.ichitasu-practice-app .problem-body{padding:16px}.ichitasu-practice-app{margin:20px auto}}

.ichitasu-practice-app .math,.ichitasu-practice-app .step-text,.ichitasu-practice-app .choice{overflow-wrap:anywhere}.ichitasu-practice-app .step-text{white-space:normal}.ichitasu-practice-app .math{font-variant-numeric:lining-nums tabular-nums}.ichitasu-practice-app .choice{line-height:1.65}