:root{--c-primary: #2563eb;--c-primary-strong: #1d4ed8;--c-primary-soft: #eff6ff;--c-bg: #dbeafe;--c-surface: #ffffff;--c-surface-muted: #f8fafc;--c-neutral-bg: #f1f5f9;--c-text: #111827;--c-text-dark: #374151;--c-text-muted: #64748b;--c-text-faint: #94a3b8;--c-neutral-fg: #475569;--c-border: #e2e8f0;--c-border-strong: #cbd5e1;--c-success-bg: #dcfce7;--c-success-fg: #166534;--c-success-soft: #f0fdf4;--c-warning-bg: #fef3c7;--c-warning-fg: #92400e;--c-danger: #dc2626;--c-danger-strong: #991b1b;--c-danger-bg: #fef2f2;--c-danger-border: #fca5a5;--radius-sm: 6px;--radius-md: 8px;--radius-lg: 12px;--shadow-shell: 0 0 40px rgba(15, 23, 42, .12);--shadow-card: 0 1px 2px rgba(15, 23, 42, .04), 0 2px 6px rgba(15, 23, 42, .06);--font-sans: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif}*{box-sizing:border-box}body{margin:0;font-family:var(--font-sans);-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;text-rendering:optimizeLegibility;background:var(--c-bg);color:var(--c-text)}button,input{font:inherit}button{width:100%;min-height:44px;border:0;border-radius:var(--radius-md);background:var(--c-primary);color:var(--c-surface);font-weight:700}button:disabled{background:var(--c-neutral-bg);color:var(--c-text-muted);cursor:not-allowed}:where(button,a,input,textarea,select,[tabindex]):focus-visible{outline:2px solid var(--c-primary);outline-offset:2px}.segmented-control label:has(input:focus-visible),.student-choice-list label:has(input:focus-visible){outline:2px solid var(--c-primary);outline-offset:2px}.student-desktop-frame{min-height:100vh;background:linear-gradient(180deg,var(--c-bg) 0%,var(--c-surface-muted) 100%)}.student-mobile-shell{position:relative;min-height:100vh;max-width:430px;margin:0 auto;background:linear-gradient(180deg,#2563eb1a,#2563eb00 180px) no-repeat,var(--c-surface);box-shadow:var(--shadow-shell)}.page{min-height:100vh;padding:32px 20px 96px}.page h1{margin:0 0 12px;font-size:26px;font-weight:700;line-height:1.25;letter-spacing:-.01em}.page h2{margin:0 0 8px;font-size:18px}.muted{color:var(--c-text-muted);line-height:1.7}.form-stack{display:grid;gap:18px;margin-top:28px}.form-stack label,.check-row{display:grid;gap:8px;font-weight:700}.check-row{grid-template-columns:auto 1fr;align-items:center;margin:28px 0}.form-stack input{width:100%;min-height:44px;border:1px solid var(--c-border-strong);border-radius:var(--radius-md);padding:0 12px}fieldset{margin:0;border:0;padding:0}legend{margin-bottom:8px;font-weight:700}.segmented-control{display:grid;grid-template-columns:1fr 1fr;gap:8px}.segmented-control.three{grid-template-columns:repeat(3,1fr)}.segmented-control label{position:relative;display:block;border:1px solid var(--c-border-strong);border-radius:var(--radius-md);padding:12px;text-align:center}.segmented-control label.selected{border-color:var(--c-primary);background:var(--c-primary-soft);color:var(--c-primary-strong)}.segmented-control input{position:absolute;top:0;right:0;bottom:0;left:0;width:100%;height:100%;margin:0;opacity:0}.summary-panel,.profile-list{margin-top:24px;border:1px solid var(--c-border);border-radius:var(--radius-md);padding:16px}.profile-list div{display:flex;justify-content:space-between;gap:16px}.profile-list dt{color:var(--c-text-muted)}.profile-list dd{margin:0;font-weight:700}.student-choice-list{display:grid;gap:8px}.student-choice-list label{position:relative;display:grid;grid-template-columns:1fr auto;align-items:center;min-height:48px;border:1px solid var(--c-border-strong);border-radius:var(--radius-md);padding:10px 12px}.student-choice-list label.selected{border-color:var(--c-primary);background:var(--c-primary-soft);color:var(--c-primary-strong)}.student-choice-list input{position:absolute;top:0;right:0;bottom:0;left:0;width:100%;height:100%;margin:0;opacity:0}.student-choice-list small{color:var(--c-text-muted);font-weight:700}.student-tabs{position:fixed;right:0;bottom:0;left:0;display:grid;grid-template-columns:repeat(4,1fr);max-width:430px;margin:0 auto;border-top:1px solid var(--c-border);background:#fffffff5;padding-bottom:env(safe-area-inset-bottom)}.student-tabs a{position:relative;display:flex;flex-direction:column;align-items:center;gap:3px;padding:8px 4px;color:var(--c-text-muted);text-align:center;text-decoration:none}.student-tab-label{font-size:11px;font-weight:700}.student-tabs a.active{color:var(--c-primary)}.notification-unread-badge{position:absolute;top:6px;left:50%;min-width:18px;height:18px;border-radius:9px;padding:0 5px;background:var(--c-danger);color:var(--c-surface);font-size:11px;line-height:18px;transform:translate(12px)}.secondary-action{display:block;color:var(--c-primary);font-weight:700;text-align:center;text-decoration:none}.error-text{margin:0;color:var(--c-danger)}.action-card-arrow{font-size:24px;color:var(--c-text-faint);font-weight:300}.home-assignments{margin-top:28px}.assignment-list{display:grid;gap:12px;margin-top:12px}.assignment-card{border:1px solid var(--c-border);border-radius:var(--radius-lg);box-shadow:var(--shadow-card);padding:16px}.assignment-card-header{display:flex;justify-content:space-between;align-items:flex-start;gap:8px}.assignment-card-header strong{font-size:16px;line-height:1.35}.assignment-status{flex-shrink:0;font-size:12px;padding:3px 10px;border-radius:999px;font-weight:700;white-space:nowrap}.status-submitted{background:var(--c-success-bg);color:var(--c-success-fg)}.status-todo{background:var(--c-warning-bg);color:var(--c-warning-fg)}.assignment-card-content{display:-webkit-box;-webkit-box-orient:vertical;-webkit-line-clamp:2;overflow:hidden;margin:8px 0 12px;font-size:14px;line-height:1.5}.due-date{display:inline-flex;align-items:center;gap:5px;font-size:13px;color:var(--c-text-muted)}.due-date.due-overdue{color:var(--c-danger);font-weight:700}.due-date.due-today{color:var(--c-warning-fg);font-weight:700}.due-date.due-soon{color:var(--c-primary-strong);font-weight:700}.assignment-attachments{display:flex;flex-wrap:wrap;gap:8px;margin:10px 0 12px}.assignment-attachment-btn{display:inline-flex;align-items:center;gap:6px;min-height:36px;max-width:100%;padding:0 12px;border:1px solid var(--c-border-strong);border-radius:var(--radius-md);background:var(--c-surface);color:var(--c-primary-strong);font-size:13px;font-weight:700}.assignment-attachment-btn svg{flex-shrink:0}.attachment-name{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.assignment-card-actions{display:flex;gap:8px;flex-wrap:wrap}.assignment-action-btn{display:flex;flex:1;align-items:center;justify-content:center;gap:6px;min-height:44px;padding:0 20px;border-radius:var(--radius-md);font-size:14px;font-weight:700;text-decoration:none;background:var(--c-primary);color:var(--c-surface)}.assignment-action-btn.btn-secondary{background:var(--c-neutral-bg);color:var(--c-primary)}.empty-state{display:flex;flex-direction:column;align-items:center;gap:8px;padding:48px 16px;text-align:center}.empty-state-icon{color:var(--c-text-faint)}.empty-state-title{margin:0;font-weight:700}.empty-state-hint{margin:0;font-size:13px}.notification-list{display:grid;gap:12px}.notification-card{display:grid;grid-template-columns:auto 1fr auto;align-items:center;gap:12px;min-height:68px;border:1px solid var(--c-border);border-radius:var(--radius-lg);box-shadow:var(--shadow-card);padding:12px 14px;color:inherit;text-decoration:none;background:var(--c-surface);transition:transform .08s ease,background .08s ease}.notification-card:active{transform:scale(.99);background:var(--c-surface-muted)}.notification-dot{width:10px;height:10px;border-radius:50%;background:var(--c-text-faint)}.notification-dot.status-pending{background:var(--c-danger)}.notification-card-body{display:grid;gap:4px;min-width:0}.notification-card-body strong{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.notification-card-body small{color:var(--c-text-muted)}.page-header{display:grid;grid-template-columns:auto 1fr;align-items:center;gap:12px;margin-bottom:20px}.page-header.single-column{grid-template-columns:1fr}.page-header h1{margin:0;font-size:20px;font-weight:700;letter-spacing:-.01em}.back-btn{width:auto;min-height:44px;padding:0 16px;background:var(--c-neutral-bg);color:var(--c-text-dark);font-size:14px}.upload-container{margin-top:16px}.upload-zone{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:120px;border:2px dashed var(--c-border-strong);border-radius:var(--radius-lg);padding:24px;text-align:center;color:var(--c-text-muted);cursor:pointer}.upload-zone:active{background:var(--c-surface-muted)}.upload-icon{display:flex;margin-bottom:8px}.file-list{display:grid;gap:10px;margin-top:16px}.file-item{display:grid;grid-template-columns:56px 1fr auto;gap:10px;align-items:center;border:1px solid var(--c-border);border-radius:var(--radius-lg);padding:10px}.file-item.status-failed{border-color:var(--c-danger-border);background:var(--c-danger-bg)}.thumbnail{width:56px;height:56px;border-radius:var(--radius-sm);object-fit:cover}.file-info{min-width:0}.file-name{font-size:13px;font-weight:700;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.upload-progress-bar{height:4px;border-radius:2px;background:var(--c-border);margin:6px 0 4px;overflow:hidden}.progress-fill{height:100%;border-radius:2px;background:var(--c-primary);transition:width .2s ease}.status-badge{display:inline-flex;align-items:center;gap:4px;font-size:12px;color:var(--c-text-muted)}.section-title{display:flex;align-items:center;gap:6px}.note-title{display:inline-flex;align-items:center;gap:4px;vertical-align:middle}.lightbox-overlay{position:fixed;top:0;right:0;bottom:0;left:0;z-index:100;display:flex;align-items:center;justify-content:center;padding:16px;background:#0f172aeb}.lightbox-image{max-width:100%;max-height:100%;object-fit:contain;border-radius:var(--radius-md);touch-action:pinch-zoom}.lightbox-close{position:fixed;top:16px;right:16px;display:inline-flex;align-items:center;width:auto;min-height:44px;padding:0 12px;background:#ffffff2e;color:#fff}.spin{animation:spin 1s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}@media (prefers-reduced-motion: reduce){.spin{animation:none}}.remove-btn{width:auto;min-height:44px;padding:0 12px;background:var(--c-neutral-bg);color:var(--c-text-muted);font-size:13px}.footer-actions{position:fixed;right:0;bottom:0;left:0;max-width:430px;margin:0 auto;padding:12px 20px;padding-bottom:calc(12px + env(safe-area-inset-bottom));background:#fffffff5;border-top:1px solid var(--c-border);z-index:10}.submit-btn{width:100%;min-height:48px;font-size:16px}.submit-error{margin:12px 0;padding:12px;border-radius:var(--radius-md);background:var(--c-danger-bg);color:var(--c-danger);font-size:14px;text-align:center}.feedback-section{margin-top:20px;padding:16px;border:1px solid var(--c-border);border-radius:var(--radius-lg);box-shadow:var(--shadow-card)}.feedback-section h3{margin:0 0 12px;font-size:16px}.feedback-section h4{margin:12px 0 8px;font-size:14px}.status-container{margin-top:8px;font-size:14px}.status-badge.status-graded{color:var(--c-success-fg)}.status-badge.status-pending{color:var(--c-warning-fg)}.comment-box{padding:12px;border-radius:var(--radius-md);background:var(--c-surface-muted);font-style:italic;line-height:1.6;word-break:break-word;overflow-wrap:break-word}.rendered-gallery,.original-gallery{display:grid;gap:12px;margin-top:8px}.annotated-image-container{position:relative}.annotated-img,.original-img{width:100%;border-radius:var(--radius-md)}.image-label{display:block;margin-top:4px;font-size:12px;color:var(--c-text-muted)}.mistake-roster{margin-top:20px}.mistake-list{display:grid;gap:12px;margin-top:8px}.mistake-item{padding:12px;border:1px solid var(--c-border);border-radius:var(--radius-lg)}.mistake-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:8px}.mistake-number{font-weight:700;font-size:14px}.status-tag{font-size:12px;padding:2px 8px;border-radius:var(--radius-sm);font-weight:700}.status-tag.unresolved{background:var(--c-warning-bg);color:var(--c-warning-fg)}.status-tag.resolved{background:var(--c-success-bg);color:var(--c-success-fg)}.status-tag.pending_review{background:var(--c-bg);color:var(--c-primary-strong)}.go-correct-btn{display:inline-flex;align-items:center;justify-content:center;min-height:44px;margin-top:8px;padding:0 16px;border-radius:var(--radius-md);background:var(--c-primary);color:var(--c-surface);font-weight:700;font-size:14px}.tab-navigation{display:grid;grid-template-columns:repeat(3,1fr);gap:8px;margin-bottom:20px}.tab-btn{min-height:44px;border-radius:var(--radius-md);font-size:14px;background:var(--c-neutral-bg);color:var(--c-neutral-fg)}.tab-btn.active{background:var(--c-primary);color:var(--c-surface)}.mistakes-page .mistake-detail-card{border:1px solid var(--c-border);border-radius:var(--radius-lg);box-shadow:var(--shadow-card);padding:16px;margin-bottom:12px}.card-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:8px}.index-label{font-weight:700;font-size:14px}.date-stamp{font-size:12px;color:var(--c-text-faint)}.crop-photo-wrap{margin:8px 0}.crop-preview{width:100%;max-height:200px;object-fit:contain;border-radius:var(--radius-md)}.comment-note{padding:10px;border-radius:var(--radius-md);background:var(--c-warning-bg);font-size:14px;line-height:1.5;margin:8px 0;word-break:break-word;overflow-wrap:break-word}.card-actions{margin-top:8px}.correct-btn-action{width:100%;min-height:44px;font-size:14px}.cancel-btn{width:auto;min-height:44px;padding:0 12px;background:var(--c-neutral-bg);color:var(--c-text-muted);font-size:13px}.retry-action-btn{width:auto;min-height:44px;padding:0 12px;background:var(--c-primary);color:var(--c-surface);font-size:13px}.resolved-panel{margin-top:12px;padding:12px;border-radius:var(--radius-md);background:var(--c-success-soft)}.pending-review-panel{margin-top:12px;padding:12px;border-radius:var(--radius-md);background:var(--c-primary-soft)}.review-status-note{margin:8px 0;padding:10px;border-radius:var(--radius-md);background:var(--c-danger-bg);color:var(--c-danger-strong);font-size:14px;line-height:1.5}.corrected-gallery{display:grid;gap:8px;margin-top:8px}.corrected-thumb{width:100%;border-radius:var(--radius-md)}.load-more-btn{min-height:44px;margin-top:16px;background:var(--c-neutral-bg);color:var(--c-neutral-fg)}.loading-text{text-align:center;padding:32px 0;color:var(--c-text-muted)}.skeleton{position:relative;overflow:hidden;background:var(--c-neutral-bg);border-radius:var(--radius-sm)}.skeleton:after{content:"";position:absolute;top:0;right:0;bottom:0;left:0;transform:translate(-100%);background:linear-gradient(90deg,transparent,rgba(255,255,255,.65),transparent);animation:skeleton-shimmer 1.4s ease-in-out infinite}.skeleton-line{height:14px;margin-bottom:10px}.skeleton-line:last-child{margin-bottom:0}@keyframes skeleton-shimmer{to{transform:translate(100%)}}@media (prefers-reduced-motion: reduce){.skeleton:after{animation:none}}.error-panel{text-align:center;padding:24px 16px}.retry-btn{width:auto;min-height:44px;margin-top:12px;padding:0 24px;background:var(--c-neutral-bg);color:var(--c-text-dark)}.error-indicator{display:grid;gap:8px;margin-top:8px}.error-hint{color:var(--c-danger);font-size:13px}.action-row{display:flex;gap:8px}.success-panel{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:60vh;text-align:center;padding:32px 16px}.success-icon{display:flex;margin-bottom:16px}.success-panel h2{margin:0 0 8px;font-size:20px}.success-panel .submit-btn{margin-top:24px;max-width:240px}@media (min-width: 431px){.student-desktop-frame{display:flex;align-items:flex-start;justify-content:center;padding-top:24px}}