:root{--ink:#1c2731;--muted:#6d7780;--paper:#fffdf8;--line:#e6e1d8;--blue:#16697a;--orange:#dc7a35;--green:#32815c}*{box-sizing:border-box}body{margin:0;background:#f3f1eb;color:var(--ink);font-family:"Microsoft YaHei",system-ui,sans-serif}.app{max-width:760px;margin:0 auto;padding:38px 20px 56px}header{display:flex;align-items:flex-end;justify-content:space-between;gap:18px;border-bottom:1px solid var(--line);padding-bottom:22px}.eyebrow{margin:0 0 5px;color:var(--orange);font-size:11px;letter-spacing:1.5px;font-weight:700}h1{margin:0;font-size:30px}.header-actions,.toolbar,.grade-row,.nav{display:flex;gap:10px;align-items:center}.toolbar{flex-wrap:wrap;padding:18px 0}.toolbar label{font-size:13px;color:var(--muted);display:flex;gap:7px;align-items:center}select,button{font:inherit}select{background:#fff;border:1px solid var(--line);border-radius:8px;padding:8px;color:var(--ink)}button,.file-label{border:0;border-radius:9px;padding:9px 13px;cursor:pointer;font-weight:700}.quiet{background:#e9edf0;color:#34434e}.file-label{display:inline-flex;align-items:center;cursor:pointer}.file-label input{display:none}.progress-panel{background:#e8eee9;border-radius:12px;padding:13px 15px;margin:2px 0 25px}.progress-copy{display:flex;justify-content:space-between;gap:15px;font-size:13px}.progress-copy span{color:var(--muted)}.bar{height:7px;background:#d1ddd3;border-radius:99px;margin-top:10px;overflow:hidden}.bar i{display:block;height:100%;width:0;background:var(--green);transition:.25s}.study{display:grid;gap:16px}.card{min-height:260px;width:100%;background:var(--paper);border:1px solid #e6dccb;box-shadow:0 10px 26px #44381b12;padding:30px;text-align:left;display:flex;flex-direction:column;align-items:flex-start}.card:hover{border-color:#cfb689}.card-side,.answer-title{font-size:12px;font-weight:700;letter-spacing:1px;color:var(--orange)}.card-content{font-size:25px;line-height:1.55;font-weight:700;margin:auto 0}.tap{font-size:13px;color:var(--muted)}.answer{background:#e7f0f0;border-radius:12px;padding:20px}.answer-content{font-size:18px;line-height:1.8;margin-top:8px;white-space:pre-line}.self-check{font-size:13px;color:var(--muted);margin:16px 0 10px}.grade-row button{color:#fff}.again{background:var(--orange)}.good{background:var(--green)}.nav{justify-content:space-between;color:var(--muted);font-size:13px}.empty{background:#fff4df;padding:22px;border-radius:12px;color:#76521d}.help{margin-top:34px;color:var(--muted);font-size:14px}.help summary{cursor:pointer;font-weight:700;color:var(--blue)}pre{overflow:auto;background:#232d32;color:#e7f3f4;padding:14px;border-radius:8px;font-size:12px}@media(max-width:560px){.app{padding:25px 15px}header{align-items:flex-start;flex-direction:column}.card{min-height:230px}.card-content{font-size:22px}.progress-copy{flex-direction:column;gap:3px}}