:root{--ink:#302c68;--muted:#686481;--cream:#faf7ef;--line:#e2deed;--purple:#eae7ff;--mint:#dff7ee}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--cream);color:var(--ink);font-family:Nunito,system-ui,sans-serif}button{font:inherit;cursor:pointer}button:focus-visible,a:focus-visible{outline:3px solid #e4a926;outline-offset:3px}[hidden]{display:none!important}
.masthead{background:#302c68;color:#fff;display:flex;align-items:center;justify-content:space-between;padding:13px max(20px,calc((100vw - 1260px)/2));gap:15px}.masthead a{color:inherit;text-decoration:none}.brand{font-size:31px;font-weight:900;letter-spacing:-2px}.back{font-weight:900;padding:8px}
.wrap{max-width:1300px;margin:auto;padding:28px 20px 70px}.intro{display:flex;justify-content:space-between;align-items:end;gap:20px;margin-bottom:24px}.eyebrow{display:inline-block;background:#dfd9ff;color:#514598;border-radius:99px;padding:7px 12px;font-size:13px;font-weight:900}.intro h1{font-size:clamp(31px,4vw,48px);line-height:1.1;margin:11px 0}.intro p{font-size:17px;color:var(--muted);margin:0;max-width:700px}.progress{font-weight:900;background:#fff;border-radius:99px;padding:12px 18px;white-space:nowrap;box-shadow:0 5px 18px #302c6811}
.worksheet{display:grid;grid-template-columns:minmax(0,42fr) minmax(0,58fr);background:#fff;border-radius:22px;box-shadow:0 12px 28px #25206012;margin-bottom:24px;overflow:hidden;scroll-margin-top:16px}.worksheet .question{padding:26px;border-right:2px dashed var(--line);min-width:0}.meta{display:flex;align-items:center;justify-content:space-between;gap:12px;font-size:14px;font-weight:900;color:#686093}.number{background:#eae7ff;padding:7px 12px;border-radius:99px;color:#514598}.question h2{font-size:clamp(20px,2.3vw,27px);line-height:1.3;margin:18px 0 14px}.math-picture{margin:17px auto 20px}.options{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px;margin-top:22px}.option{border:2px solid transparent;background:#f5f3ff;color:var(--ink);border-radius:13px;padding:12px;text-align:left;display:flex;align-items:center;gap:10px;min-height:58px;font-size:18px;font-weight:900}.option.selected{border-color:#544a9f;background:#e7e3ff}.letter{display:grid;place-items:center;flex:none;width:28px;height:28px;background:#e5e0f7;border-radius:8px;font-size:14px}.actions{display:flex;flex-wrap:wrap;align-items:center;gap:9px;margin-top:18px}.check,.hint-button{border:0;border-radius:99px;padding:11px 18px;font-weight:900}.check{background:#342e83;color:#fff}.hint-button{background:#f1ecff;color:var(--ink)}.feedback{font-weight:900;border-radius:12px;padding:12px;margin:15px 0 0;background:#fff0d7}.feedback.correct{background:#def6e9;color:#176650}.hint,.explanation{background:#f4f0ff;padding:13px;border-radius:12px;margin:13px 0 0;line-height:1.5}.explanation{background:#e9f6f0}.explanation strong{display:block;margin-bottom:5px}.explanation ol{margin:0;padding-left:23px}
.working{padding:22px;display:flex;flex-direction:column;min-width:0}.workhead{display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap}.workhead h3{font-size:22px;margin:0}.tools{display:flex;gap:6px;flex-wrap:wrap}.tools button{background:#f0eff9;color:var(--ink);border:0;border-radius:9px;font-weight:900;padding:9px 11px;min-height:42px}.tools button.active{background:#c4f0e6}.scratch{display:block;width:100%;height:310px;flex:1;min-height:310px;background:#fffefa;border:1px solid #e6e2ef;border-radius:14px;margin-top:17px;touch-action:none;cursor:crosshair}.worknote{color:var(--muted);font-size:13px;margin:10px 0 0;font-weight:700}
@media(max-width:720px){.intro{align-items:start;flex-direction:column}.worksheet{grid-template-columns:1fr}.worksheet .question{border-right:0;border-bottom:2px dashed var(--line)}.working{min-height:320px}.scratch{height:280px;min-height:280px}.wrap{padding:22px 14px 70px}}
@media(max-width:390px){.question,.working{padding:18px!important}.options{gap:7px}.option{font-size:16px;padding:9px;min-height:54px}}