:root{--navy:#1e2761;--ice:#cadcfc;--white:#ffffff;--ink:#1b1f2a;--muted:#5b6472;--good:#1e7a3a;--bad:#b3261e;--border:#dfe4ee}*{box-sizing:border-box}[hidden]{display:none!important}body{margin:0;font-family:-apple-system,"Segoe UI",Arial,sans-serif;color:var(--ink);background:var(--white);display:flex;justify-content:center;padding:32px 16px}.app{width:100%;max-width:520px}.app-header{text-align:center;margin-bottom:32px}.app-header h1{font-size:28px;margin:0 0 6px;color:var(--navy)}.subtitle{margin:0;color:var(--muted);font-size:15px;font-style:italic}.top-nav{display:flex;flex-wrap:wrap;justify-content:center;gap:8px 16px;margin-top:14px}.nav-link{font-size:13px;font-weight:600;color:var(--navy);text-decoration:none}.nav-link:hover{text-decoration:underline}.nav-link.nav-exit{color:var(--muted)}.screen-root{position:relative}.screen{border:1px solid var(--border);border-radius:12px;padding:28px 24px}.lead{font-size:16px;margin-top:0}label{display:block;font-size:13px;font-weight:600;margin-bottom:6px;color:var(--muted)}input[type=text]{width:100%;padding:10px 12px;font-size:16px;border:1px solid var(--border);border-radius:8px;margin-bottom:16px}.btn{display:inline-block;width:100%;padding:12px 16px;font-size:16px;font-weight:600;border-radius:8px;border:none;cursor:pointer}.btn-primary{background:var(--navy);color:var(--white)}.btn-primary:hover{opacity:.92}.btn-secondary{background:var(--white);color:var(--navy);border:1px solid var(--border);margin-bottom:16px}.btn-secondary:hover:not(:disabled){background:var(--ice)}.btn-secondary:disabled{opacity:.6;cursor:default}.error{color:var(--bad);font-size:14px;margin-top:8px}.progress{font-size:13px;color:var(--muted);margin:0 0 4px}.source{font-size:12px;color:var(--muted);margin:0 0 12px;text-transform:uppercase;letter-spacing:.03em;overflow-wrap:break-word}.source a{color:var(--muted)}.source a:hover{color:var(--navy)}#question-text{font-size:20px;line-height:1.4;margin:0 0 20px}.choices{display:flex;flex-direction:column;gap:10px;margin-bottom:16px}.choice-btn{text-align:left;padding:12px 14px;font-size:15px;border:1px solid var(--border);border-radius:8px;background:var(--white);cursor:pointer}.choice-btn:hover:not(:disabled){border-color:var(--navy);background:var(--ice)}.choice-btn:disabled{cursor:default}.choice-btn.correct{border-color:var(--good);background:#e6f4ea;font-weight:600}.choice-btn.incorrect{border-color:var(--bad);background:#fbe9e7}.feedback{font-weight:600;margin-bottom:16px}.feedback.correct{color:var(--good)}.feedback.incorrect{color:var(--bad)}.detail{font-size:14px;color:var(--muted);line-height:1.5;margin:-8px 0 16px}.highscore-list{list-style:none;padding:0;margin:0 0 24px;counter-reset:rank}.highscore-list li{display:flex;justify-content:space-between;padding:8px 0;border-bottom:1px solid var(--border);font-size:15px}.highscore-list li:before{counter-increment:rank;content:counter(rank) ".";color:var(--muted);width:24px;flex-shrink:0}.highscore-list li.me{font-weight:700;color:var(--navy)}