:root {
            --primary: #6366f1;
            --primary-soft: #eef2ff;
            --bg: #f8fafc;
            --card: #ffffff;
            --text-main: #1e293b;
            --text-muted: #64748b;
            --border: #e2e8f0;
            --high: #ef4444;
            --medium: #f59e0b;
            --low: #10b981;
        }

        * { margin: 0; padding: 0; box-sizing: border-box; font-family: 'Plus Jakarta Sans', sans-serif; }
        body { background-color: var(--bg); color: var(--text-main); display: flex; min-height: 100vh; }

        /* Sidebar Navigation */
        aside { width: 280px; background: var(--card); border-right: 1px solid var(--border); padding: 2rem; display: flex; flex-direction: column; position: sticky; top: 0; height: 100vh; }
        .logo { font-size: 1.5rem; font-weight: 700; color: var(--primary); margin-bottom: 2.5rem; display: flex; align-items: center; gap: 10px; }
        nav { flex: 1; }
        nav button { width: 100%; padding: 0.8rem 1rem; margin-bottom: 0.5rem; border: none; border-radius: 10px; background: transparent; color: var(--text-muted); text-align: left; cursor: pointer; font-weight: 500; transition: 0.2s; }
        nav button.active { background: var(--primary-soft); color: var(--primary); }
        nav button:hover:not(.active) { background: #f1f5f9; }

        /* Main Content */
        main { flex: 1; padding: 2.5rem; max-width: 1100px; margin: 0 auto; }
        header { margin-bottom: 2rem; }
        header h1 { font-size: 1.8rem; margin-bottom: 0.5rem; }
        header p { color: var(--text-muted); }

        /* Stats Grid */
        .stats-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.5rem; margin-bottom: 2.5rem; }
        .stat-box { background: var(--card); padding: 1.5rem; border-radius: 16px; border: 1px solid var(--border); box-shadow: 0 4px 6px -1px rgba(0,0,0,0.05); }
        .stat-box h3 { font-size: 0.85rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 0.5rem; }
        .stat-box .val { font-size: 1.8rem; font-weight: 700; }

        /* Form Area */
        .input-card { background: var(--card); padding: 1.5rem; border-radius: 16px; border: 1px solid var(--border); margin-bottom: 2rem; }
        .input-group { display: grid; grid-template-columns: 2fr 1fr 1fr auto; gap: 1rem; }
        input, select { padding: 0.75rem; border: 1px solid var(--border); border-radius: 8px; font-size: 0.9rem; outline-color: var(--primary); }
        .btn-add { background: var(--primary); color: white; border: none; padding: 0.75rem 1.5rem; border-radius: 8px; font-weight: 600; cursor: pointer; transition: 0.2s; }
        .btn-add:hover { opacity: 0.9; transform: translateY(-1px); }

        /* Task List */
        .section-title { margin-bottom: 1rem; font-size: 1.1rem; font-weight: 600; color: var(--text-muted); display: flex; align-items: center; gap: 8px; }
        .task-list { display: flex; flex-direction: column; gap: 0.75rem; }
        .task-item { background: var(--card); padding: 1rem 1.5rem; border-radius: 12px; border: 1px solid var(--border); display: flex; align-items: center; justify-content: space-between; transition: 0.2s; }
        .task-item:hover { border-color: var(--primary); }
        .task-info { display: flex; align-items: center; gap: 1rem; }
        .priority-indicator { width: 12px; height: 12px; border-radius: 4px; }
        .task-meta { font-size: 0.8rem; color: var(--text-muted); margin-top: 2px; }
        .actions { display: flex; gap: 0.5rem; }
        .btn-icon { background: #f1f5f9; border: none; width: 32px; height: 32px; border-radius: 6px; cursor: pointer; display: flex; align-items: center; justify-content: center; }
        
        /* Tab Logic */
        .page-section { display: none; }
        .page-section.active { display: block; }

        /* Calendar Placeholder */
        .calendar-grid { display: grid; grid-template-columns: repeat(7, 1fr); gap: 5px; background: var(--border); border: 1px solid var(--border); }
        .calendar-day { background: white; height: 100px; padding: 10px; font-size: 0.8rem; }

        @media (max-width: 900px) {
            aside { display: none; }
            .input-group { grid-template-columns: 1fr; }
            .stats-grid { grid-template-columns: 1fr; }
        }