:root{font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;color:#17223b;background:#f4f7fb;font-synthesis:none}*{box-sizing:border-box}body{margin:0;min-width:320px;min-height:100vh}button,input,textarea{font:inherit}.page-shell{width:min(100% - 32px,720px);margin:0 auto;padding:24px 0 48px}.brand{display:flex;align-items:center;gap:10px;margin-bottom:28px;font-weight:750}.brand-mark{display:grid;place-items:center;width:38px;height:38px;border-radius:12px;color:#fff;background:#5367e8;font-size:13px}.exercise-card,.state-card{padding:24px 20px;border:1px solid #e2e8f2;border-radius:22px;background:#fff;box-shadow:0 12px 40px #18274b14}.exercise-card h1,.state-card h1{margin:20px 0 18px;font-size:clamp(1.25rem,5vw,1.65rem)}.tags{display:flex;flex-wrap:wrap;gap:8px}.tag{padding:6px 10px;border-radius:999px;background:#edf1f7;color:#536078;font-size:.78rem;font-weight:700}.tag-accent{background:#ebeefe;color:#4356cc}.sentence{display:flex;flex-wrap:wrap;align-items:baseline;gap:7px 0;font-size:clamp(1.25rem,5.4vw,1.75rem);line-height:1.75;font-weight:600}.sentence>span{white-space:pre-wrap}.gap-input{width:clamp(3.25rem,calc(var(--gap-size) * .78em + 1.2rem),11rem);min-width:3.25rem;margin:0 4px;padding:4px 5px 2px;border:0;border-bottom:2px solid #8795b0;border-radius:6px 6px 2px 2px;outline:none;background:#f6f8fc;color:#17223b;text-align:center;font-weight:700;transition:border-color .15s,background .15s,box-shadow .15s}.gap-input:focus{border-color:#5367e8;background:#eef0ff;box-shadow:0 2px #5367e8}.gap-input:disabled{color:#43506a;opacity:.85}.translation{margin:20px 0 24px;color:#68758c;line-height:1.55}button{display:flex;align-items:center;justify-content:center;gap:9px;width:100%;min-height:50px;padding:12px 18px;border:0;border-radius:14px;background:#5367e8;color:#fff;cursor:pointer;font-weight:750}button:hover:not(:disabled){background:#4356d3}button:focus-visible{outline:3px solid #b7c0ff;outline-offset:2px}button:disabled{cursor:wait;opacity:.7}.message,.api-error{display:flex;flex-direction:column;gap:5px;margin:0 0 16px;padding:12px 14px;border-radius:12px;font-size:.92rem;line-height:1.45}.success{color:#17603a;background:#e7f7ee}.incorrect{color:#8a4318;background:#fff1e5}.correct-answer{margin-top:5px;font-size:1.12rem;line-height:1.55;font-weight:750}.error,.api-error{color:#9b2735;background:#fdecef}.state-card{display:grid;justify-items:center;text-align:center;color:#68758c}.state-card button{margin-top:8px}.error-state h1{color:#17223b}.spinner{width:18px;height:18px;border:2px solid rgb(255 255 255 / 45%);border-top-color:#fff;border-radius:50%;animation:spin .75s linear infinite}.spinner.large{width:30px;height:30px;border-color:#d9def9;border-top-color:#5367e8}.report-action{width:auto;min-height:40px;margin:14px auto -8px;padding:8px 10px;background:transparent;color:#68758c;font-size:.88rem;font-weight:650}.report-action:hover:not(:disabled){background:#f2f4f8;color:#43506a}.sheet-backdrop{position:fixed;z-index:20;top:0;right:0;bottom:0;left:0;display:flex;align-items:flex-end;justify-content:center;padding-top:24px;background:#141d307a}.report-sheet{width:min(100%,560px);max-height:calc(100vh - 24px);overflow-y:auto;padding:10px 20px max(24px,env(safe-area-inset-bottom));border-radius:24px 24px 0 0;background:#fff;box-shadow:0 -12px 40px #18274b2e}.sheet-handle{width:42px;height:4px;margin:0 auto 12px;border-radius:4px;background:#d5dbe6}.sheet-heading{display:flex;align-items:center;justify-content:space-between;gap:12px}.sheet-heading h2{margin:4px 0 16px;font-size:1.2rem}.icon-button{width:40px;min-height:40px;padding:0;background:transparent;color:#68758c;font-size:1.65rem}.icon-button:hover:not(:disabled){background:#f2f4f8}.reason-option{display:flex;align-items:center;gap:12px;min-height:46px;cursor:pointer}.reason-option input{width:20px;height:20px;accent-color:#5367e8}.comment-label{display:block;margin:15px 0 7px;font-weight:700}.comment-label span,.character-count{color:#7a869b;font-size:.8rem;font-weight:500}textarea{display:block;width:100%;resize:vertical;padding:11px 12px;border:1px solid #cfd7e5;border-radius:12px;color:#17223b}textarea:focus{border-color:#5367e8;outline:2px solid #dfe3ff}.character-count{display:block;margin:4px 2px 12px;text-align:right}.report-sheet .message{margin-bottom:12px}.report-success{display:grid;gap:8px;padding:20px 0 4px;text-align:center}.report-success strong{color:#17603a;font-size:1.25rem}.report-success button{margin-top:12px}@keyframes spin{to{transform:rotate(360deg)}}@media (min-width: 600px){.page-shell{padding-top:40px}.exercise-card,.state-card{padding:34px}}@media (prefers-reduced-motion: reduce){*,*:before,*:after{scroll-behavior:auto!important;animation-duration:.01ms!important;animation-iteration-count:1!important}}