/* ===== 学习计划样式 ===== */
        .plan-overlay {
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: rgba(0,0,0,0.5);
            z-index: 1002;
            display: none;
            align-items: flex-end;
            justify-content: center;
        }
        .plan-overlay.show { display: flex; }
        .plan-sheet {
            background: white;
            border-radius: 24px 24px 0 0;
            width: 100%;
            max-width: 430px;
            max-height: 90vh;
            overflow-y: auto;
            transform: translateY(100%);
            transition: transform 0.3s ease;
        }
        .plan-overlay.show .plan-sheet { transform: translateY(0); }
        .plan-loading {
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            padding: 60px 20px;
        }
        .plan-loading-spinner {
            width: 40px;
            height: 40px;
            border: 3px solid #F1F5F9;
            border-top-color: #6C5CE7;
            border-radius: 50%;
            animation: spin 0.8s linear infinite;
        }
        @keyframes spin { to { transform: rotate(360deg); } }
        .plan-loading-text { font-size: 15px; color: #64748B; margin-top: 16px; }
        .plan-content { padding: 20px; }
        .plan-week-card {
            background: #FFFFFF;
            border: 1px solid #F0F0F5;
            border-radius: 16px;
            margin-bottom: 16px;
            overflow: hidden;
        }
        .plan-week-header {
            background: linear-gradient(135deg, #6C5CE7 0%, #A29BFE 100%);
            color: white;
            padding: 16px;
            display: flex;
            align-items: center;
            gap: 12px;
        }
        .plan-week-icon {
            width: 40px;
            height: 40px;
            background: rgba(255,255,255,0.2);
            border-radius: 12px;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        .plan-week-icon svg { width: 20px; height: 20px; stroke: white; stroke-width: 2; }
        .plan-week-title { font-size: 16px; font-weight: 700; }
        .plan-week-desc { font-size: 12px; opacity: 0.8; margin-top: 2px; }
        .plan-tasks { padding: 12px 16px; }
        .plan-task {
            display: flex;
            align-items: flex-start;
            gap: 10px;
            padding: 10px 0;
            border-bottom: 1px solid #F1F5F9;
        }
        .plan-task:last-child { border-bottom: none; }
        .plan-task-check {
            width: 20px;
            height: 20px;
            border-radius: 50%;
            background: #F1F5F9;
            border: 2px solid #E2E8F0;
            flex-shrink: 0;
            margin-top: 2px;
            cursor: pointer;
            transition: all 0.2s;
        }
        .plan-task-check.done { background: #00B894; border-color: #00B894; }
        .plan-task-check.done::after {
            content: '';
            display: block;
            width: 6px;
            height: 10px;
            border: 2px solid white;
            border-top: none;
            border-left: none;
            transform: rotate(45deg) translate(-1px, -1px);
            margin: 2px auto;
        }
        .plan-task-text { font-size: 14px; color: #475569; line-height: 1.5; }
        .plan-task.done .plan-task-text { text-decoration: line-through; color: #94A3B8; }
        .plan-actions {
            display: flex;
            gap: 10px;
            margin-top: 20px;
        }
        .plan-actions button {
            flex: 1;
            padding: 14px;
            border-radius: 12px;
            font-size: 14px;
            font-weight: 600;
            cursor: pointer;
            border: none;
            transition: all 0.2s;
        }
        .plan-actions .btn-secondary { background: #F1F5F9; color: #475569; }
        .plan-actions .btn-primary { background: #6C5CE7; color: white; }