.mobile-page .phone{background:linear-gradient(to bottom,#e3f2fd,#f5f7fa 18% 100%);display:flex;flex-direction:column}.nav-bar{height:44px;display:flex;align-items:center;padding:0 var(--mobile-padding);gap:10px}.nav-back{width:28px;height:28px;display:flex;align-items:center;justify-content:center;cursor:pointer;flex-shrink:0}.nav-back svg{width:20px;height:20px;stroke:#111827;fill:none;stroke-width:2.2;stroke-linecap:round;stroke-linejoin:round}.nav-title{font-size:17px;font-weight:var(--fw-bold);color:#111827}.scroll-content{flex:1;overflow-y:auto;padding:0 var(--mobile-padding) 20px}.hw-info-card,.class-selector,.summary-stats,.student-card{background:#fff;border-radius:12px;box-shadow:0 1px 4px #0000000f;margin-bottom:12px}.hw-info-card{padding:14px}.hw-info-main{display:flex;gap:12px;align-items:flex-start}.paper-cover{width:64px;height:82px;border-radius:12px;position:relative;overflow:hidden;flex-shrink:0;background:#f7fbff;border:1px solid rgba(223,232,243,.92);box-shadow:inset 0 1px #ffffffdb}.paper-cover:before,.paper-cover:after{content:"";position:absolute;pointer-events:none}.paper-cover.math:before{inset:0 auto auto 0;width:100%;height:30px;background:linear-gradient(135deg,#fff 0 58%,#6ed7ff 58% 100%)}.paper-cover.math:after{left:0;right:0;bottom:16px;height:24px;background:linear-gradient(135deg,transparent 0 16%,#2ec5f5 16% 100%)}.paper-cover.school:before{inset:auto 0 0;height:40px;background:linear-gradient(180deg,#2abdd8,#36d0d0)}.paper-cover.school:after{left:8px;right:8px;bottom:9px;height:18px;border-radius:16px 16px 6px 6px;border:2px solid rgba(255,255,255,.78)}.paper-cover .cover-brand,.paper-cover .cover-main,.paper-cover .cover-sub{position:absolute;z-index:1}.paper-cover .cover-brand{top:6px;left:6px;right:6px;color:#64748b;font-size:6px;font-weight:var(--fw-semibold);line-height:1.25}.paper-cover .cover-main{left:8px;bottom:25px;font-size:18px;line-height:1;color:#1d4ed8;font-weight:800;letter-spacing:1px}.paper-cover .cover-sub{right:8px;bottom:6px;color:#5e6d7f;font-size:8px;line-height:1.2;font-weight:var(--fw-medium);text-align:right}.paper-cover.school .cover-main{left:9px;top:28px;bottom:auto;font-size:14px;color:#1f2937;letter-spacing:0}.paper-cover.school .cover-sub{right:auto;left:9px;bottom:24px;color:#f8fafc;font-size:7px;line-height:1.2;text-align:left}.hw-info-text{flex:1;min-width:0}.hw-title{color:#111827;font-size:15px;font-weight:700;line-height:1.45}.record-meta{margin-top:6px;display:flex;gap:12px;flex-wrap:wrap;font-size:12px;color:#7a8699}.record-meta strong{margin-left:4px;color:#344256;font-weight:var(--fw-semibold)}.record-tags{margin-top:8px;display:flex;flex-wrap:wrap;gap:6px}.record-tag{display:inline-flex;align-items:center;padding:5px 10px;border-radius:999px;background:#f3f6fb;color:#607086;font-size:11px;line-height:1;border:1px solid rgba(222,230,240,.92)}.record-tag.primary{color:#2563eb;background:#eef4ff;border-color:#bfdbfee6}.record-publisher{margin-top:8px;font-size:12px;color:#56657b;line-height:1.45}.hw-status{margin-top:8px;font-size:12px;color:var(--text-secondary);line-height:1.45}.hw-status strong{color:var(--brand-primary);font-weight:var(--fw-semibold)}.class-selector{padding:0;position:relative}.class-select-btn{width:100%;display:flex;align-items:center;justify-content:space-between;padding:14px;font-size:15px;font-weight:var(--fw-medium);color:#111827;cursor:pointer;border:none;background:transparent;font-family:inherit}.class-select-btn.disabled{color:var(--text-secondary);cursor:default}.class-select-btn.disabled svg{opacity:.45;transform:none}.class-select-btn svg{width:16px;height:16px;stroke:var(--text-muted);fill:none;stroke-width:2;transition:transform .2s ease}.class-select-btn.open svg{transform:rotate(180deg)}.class-dropdown{display:none;border-top:1px solid var(--border-light);max-height:200px;overflow-y:auto}.class-dropdown.show{display:block}.class-option{padding:12px 14px;font-size:14px;color:var(--text-secondary);cursor:pointer;border-bottom:1px solid #f8f8f8;display:flex;align-items:center;justify-content:space-between;transition:background .15s}.class-option:last-child{border-bottom:none}.class-option:hover{background:#f8fafc}.class-option.active{color:var(--brand-primary);font-weight:var(--fw-medium);background:var(--brand-primary-bg)}.class-option.active:after{content:"";width:16px;height:16px;background:url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%231B78F8' stroke-width='2.5'%3e%3cpolyline points='20 6 9 17 4 12'/%3e%3c/svg%3e") no-repeat center;flex-shrink:0}.summary-stats{display:flex;padding:12px 14px;gap:8px;justify-content:space-around;text-align:center}.stat-item .stat-num{font-size:22px;font-weight:var(--fw-bold);display:block;line-height:1.3}.stat-item .stat-label{font-size:11px;color:var(--text-muted);margin-top:2px}.student-card{overflow:hidden}.student-card-header{padding:12px 14px;font-size:var(--font-md);font-weight:var(--fw-semibold);color:var(--text-primary);border-bottom:1px solid var(--border-light);display:flex;align-items:center;justify-content:space-between}.student-card-header .sub-text{font-size:12px;font-weight:400;color:var(--text-muted)}.action-btn-sm{padding:6px 12px;border-radius:14px;background:var(--brand-primary, #1B78F8);color:#fff;font-size:13px;font-weight:var(--fw-medium, 500);border:none;cursor:pointer}.action-btn-sm:active{opacity:.8}.student-item{padding:10px 14px;display:flex;align-items:center;gap:10px;border-bottom:1px solid #f8f8f8;transition:background .15s;cursor:pointer}.student-item:last-child{border-bottom:none}.student-item:active{background:#f6f8fa}.student-avatar{width:32px;height:32px;border-radius:50%;background:linear-gradient(135deg,#d9f3ee,#c1e8e1);display:flex;align-items:center;justify-content:center;font-size:12px;font-weight:var(--fw-semibold);color:#0f766e;flex-shrink:0}.student-name{flex:1;font-size:var(--font-base);font-weight:var(--fw-medium);color:var(--text-primary);min-width:0;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.page-dots{display:flex;gap:4px;flex-shrink:0}.page-dot{min-width:24px;height:24px;padding:0 4px;border-radius:5px;font-size:11px;font-weight:var(--fw-semibold);display:flex;align-items:center;justify-content:center;transition:all .2s ease}.page-dot.done{background:var(--success-bg);color:var(--success-text)}.page-dot.empty{background:#f0f0f0;color:#bbb}.filter-bar{display:flex;overflow-x:auto;gap:8px;padding:12px 14px 4px;scrollbar-width:none}.filter-bar::-webkit-scrollbar{display:none}.filter-chip{flex-shrink:0;padding:6px 14px;border-radius:16px;font-size:13px;background:#f4f6f8;color:var(--text-secondary);border:1px solid transparent;cursor:pointer;transition:all .2s ease}.filter-chip.active{background:var(--brand-primary-bg);color:var(--brand-primary);border-color:#1b78f84d;font-weight:var(--fw-medium)}.legend{display:flex;align-items:center;gap:16px;padding:10px 14px;font-size:11px;color:var(--text-muted)}.legend-item{display:flex;align-items:center;gap:4px}.legend-dot{width:12px;height:12px;border-radius:3px}.legend-dot.green{background:var(--success-bg);border:1px solid #bde4be}.legend-dot.gray{background:#f0f0f0;border:1px solid #ddd}.copy-bar{padding:12px 14px;border-top:1px solid var(--border-light);text-align:center}.copy-btn{display:inline-flex;align-items:center;gap:6px;padding:8px 20px;border-radius:20px;border:1px solid var(--brand-primary);background:var(--brand-primary-bg);color:var(--brand-primary);font-size:13px;font-weight:var(--fw-medium);cursor:pointer;transition:all .2s ease}.copy-btn:active{background:var(--brand-primary);color:#fff}.copy-btn svg{width:14px;height:14px;stroke:currentColor;fill:none;stroke-width:2}.toast-notification{position:fixed;top:80px;left:50%;transform:translate(-50%) translateY(-20px);background:#000000bf;color:#fff;padding:10px 24px;border-radius:20px;font-size:13px;z-index:999;opacity:0;pointer-events:none;transition:all .3s ease}.toast-notification.show{opacity:1;transform:translate(-50%) translateY(0)}