:root{--bg: #faf9f7;--card: #ffffff;--ink: #2c2a28;--ink-soft: #6b6560;--ink-faint: #a39d96;--brand: #4a7c6f;--brand-soft: #eaf1ee;--line: #ebe7e2;--radius: 16px}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font-family:-apple-system,BlinkMacSystemFont,PingFang SC,Microsoft YaHei,sans-serif;-webkit-font-smoothing:antialiased}.wrap{max-width:560px;margin:0 auto;padding:24px 20px 40px;min-height:100vh;display:flex;flex-direction:column}.topbar{display:flex;align-items:center;justify-content:space-between;color:var(--ink-faint);font-size:14px;margin-bottom:32px}.topbar button{background:none;border:none;color:var(--ink-faint);font-size:14px;cursor:pointer;padding:4px 8px}.stage{flex:1;display:flex;flex-direction:column;justify-content:center;align-items:center;text-align:center;gap:20px}.subject-tag{display:inline-block;background:var(--brand-soft);color:var(--brand);font-size:14px;padding:5px 14px;border-radius:999px}.task-title{font-size:27px;line-height:1.5;font-weight:600;margin:0;letter-spacing:.2px}.task-minutes{color:var(--ink-soft);font-size:16px}.btn-primary{background:var(--brand);color:#fff;border:none;border-radius:999px;padding:16px 52px;font-size:18px;font-weight:500;cursor:pointer;transition:opacity .15s}.btn-primary:active{opacity:.85}.btn-ghost{background:none;border:1px solid var(--line);border-radius:999px;padding:11px 22px;font-size:15px;color:var(--ink-soft);cursor:pointer}.btn-text{background:none;border:none;color:var(--ink-faint);font-size:14px;cursor:pointer;padding:8px}.timer-num{font-size:76px;font-weight:300;font-variant-numeric:tabular-nums;letter-spacing:2px;margin:8px 0}.timer-hint{color:var(--ink-faint);font-size:14px}.row{display:flex;gap:12px;align-items:center;justify-content:center}.totals{border-top:1px solid var(--line);padding-top:18px;margin-top:28px;display:flex;flex-wrap:wrap;gap:22px 28px;justify-content:center}.total-cell{text-align:center}.total-num{font-size:22px;font-weight:600;color:var(--brand);font-variant-numeric:tabular-nums}.total-label{font-size:12px;color:var(--ink-faint);margin-top:3px}.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:20px}.sheet-mask{position:fixed;top:0;right:0;bottom:0;left:0;background:#1e1c1a52;display:flex;align-items:flex-end;justify-content:center;z-index:50}.sheet{background:var(--card);width:100%;max-width:560px;border-radius:20px 20px 0 0;padding:24px 20px calc(24px + env(safe-area-inset-bottom));animation:rise .2s ease-out}@keyframes rise{0%{transform:translateY(16px);opacity:0}}.sheet h3{margin:0 0 16px;font-size:18px;font-weight:600}.field{width:100%;border:1px solid var(--line);border-radius:12px;padding:13px 14px;font-size:16px;font-family:inherit;color:var(--ink);background:var(--bg);outline:none;resize:none}.field:focus{border-color:var(--brand)}.chips{display:flex;flex-wrap:wrap;gap:8px;margin:12px 0 16px}.chip{border:1px solid var(--line);background:none;border-radius:999px;padding:7px 15px;font-size:14px;color:var(--ink-soft);cursor:pointer}.chip.on{background:var(--brand-soft);border-color:var(--brand);color:var(--brand)}.empty{text-align:center;color:var(--ink-soft);line-height:1.9;font-size:17px}.how-card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:18px 20px;margin-top:24px;text-align:left;width:100%}.how-title{font-size:13px;color:var(--brand);letter-spacing:1px;margin-bottom:10px}.how-step{margin:0 0 9px;font-size:15.5px;line-height:1.7;color:var(--ink)}.how-step:last-child{margin-bottom:0}.has-tabbar{padding-bottom:86px}.page{flex:1;display:flex;flex-direction:column}.tabbar{position:fixed;left:0;right:0;bottom:0;display:flex;background:#fffffff0;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);border-top:1px solid var(--line);padding-bottom:env(safe-area-inset-bottom);z-index:40}.tabbar-item{flex:1;background:none;border:none;padding:9px 0 7px;color:var(--ink-faint);font-size:11px;cursor:pointer;display:flex;flex-direction:column;align-items:center;gap:3px}.tabbar-item.on{color:var(--brand)}.tabbar-icon{font-size:19px;position:relative;line-height:1}.tabbar-label{font-size:11px}.tabbar-count{position:absolute;top:-5px;left:13px;background:var(--brand-soft);color:var(--brand);border-radius:999px;font-size:10px;padding:0 5px;line-height:15px;min-width:15px}.section-title{font-size:13px;color:var(--ink-faint);margin:0 0 10px;letter-spacing:.5px}.list-row{width:100%;background:var(--card);border:1px solid var(--line);border-radius:12px;padding:15px 16px;margin-bottom:8px;font-size:16px;color:var(--ink);text-align:left;cursor:pointer;display:flex;justify-content:space-between;align-items:center;gap:12px;font-family:inherit}.row-tag{font-size:12px;color:var(--ink-faint);white-space:nowrap}.row-tag.dim{opacity:.7}.material-body{white-space:pre-wrap;line-height:1.85;font-size:15.5px;color:var(--ink)}.answer-box{margin-top:20px;background:var(--brand-soft);border-radius:var(--radius);padding:18px 20px}.check-warn{background:#fdf6e8;border:1px solid #f0e0bd;color:#8a6d2f;border-radius:12px;padding:12px 14px;font-size:14px;line-height:1.7;margin-bottom:16px}.milestone{margin-bottom:10px}.milestone-title{font-size:17px;font-weight:600;color:var(--brand)}.milestone-note{font-size:14px;color:var(--ink-soft);line-height:1.7;margin-top:5px}.reward-row{margin-bottom:10px;display:flex;justify-content:space-between;align-items:center;gap:14px}.unlock-sheet{text-align:center}.unlock-title{font-size:22px;font-weight:600;color:var(--brand);margin-bottom:6px}.tutor-page{padding-bottom:76px}.tutor-intro{background:var(--brand-soft);border-radius:var(--radius);padding:15px 17px;font-size:14.5px;line-height:1.8;color:var(--ink);margin-bottom:14px}.tutor-block{font-size:14px;color:var(--ink-soft);background:var(--card);border:1px solid var(--line);border-radius:12px;padding:12px 14px;margin-bottom:16px;line-height:1.7}.tutor-msgs{flex:1;display:flex;flex-direction:column;gap:12px}.bubble{max-width:85%;padding:12px 15px;border-radius:16px;font-size:15.5px;line-height:1.75;white-space:pre-wrap}.bubble.student{align-self:flex-end;background:var(--brand);color:#fff;border-bottom-right-radius:5px}.bubble.tutor{align-self:flex-start;background:var(--card);border:1px solid var(--line);border-bottom-left-radius:5px}.bubble.dim{color:var(--ink-faint)}.tutor-input{position:fixed;left:0;right:0;bottom:0;display:flex;gap:8px;padding:10px 16px calc(10px + env(safe-area-inset-bottom));background:#faf9f7f5;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);border-top:1px solid var(--line);max-width:560px;margin:0 auto}.send-btn{padding:0 20px;border-radius:12px}.login-box{max-width:340px;margin:18vh auto;padding:0 20px}.login-box h1{font-size:22px;font-weight:600;margin-bottom:28px;text-align:center}.login-box .field{margin-bottom:12px}.login-box .btn-primary{width:100%;padding:14px}.err{color:#a8574d;font-size:14px;margin-top:12px;text-align:center}