:root {
            --primary: #0b2545;
            --secondary: #134074;
            --accent: #ee6c4d;
            --light: #f4f6f9;
            --dark: #111827; /* Leonardo.ai jaisa dark gray/black background */
            --sidebar-bg: #1e293b;
            --success: #2ec4b6;
        }

        * { box-sizing: border-box; margin: 0; padding: 0; font-family: 'Segoe UI', sans-serif; }
        body { background-color: var(--light); color: #1d2d44; position: relative; overflow-x: hidden; }

        /* HEADER & MENU BAR */
        .top-navbar {
            background: var(--primary);
            color: white;
            padding: 15px;
            display: flex;
            align-items: center;
            gap: 15px;
            font-size: 1.2rem;
            font-weight: bold;
            box-shadow: 0 2px 10px rgba(0,0,0,0.1);
        }
        .menu-trigger { font-size: 1.5rem; cursor: pointer; background: none; border: none; color: white; }

        header { 
            background: linear-gradient(135deg, var(--primary), var(--secondary)); 
            color: white; text-align: center; padding: 2.5rem 1rem; 
            border-bottom: 5px solid var(--accent); border-radius: 0 0 20px 20px; margin-bottom: 1.5rem;
        }

        /* SCREENS SYSTEM */
        .screen { display: none; padding: 1rem; max-width: 800px; margin: 0 auto; }
        .active { display: block; }

        /* SUBJECT CARDS STYLING */
        .grid { display: grid; grid-template-columns: 1fr; gap: 1.2rem; margin-top: 1.5rem; }
        @media(min-width: 600px) { .grid { grid-template-columns: 1fr 1fr; } }

        .card { 
            background: white; padding: 1.5rem; border-radius: 12px; 
            border-left: 6px solid var(--secondary); box-shadow: 0 4px 12px rgba(0,0,0,0.05); 
            cursor: pointer; font-weight: bold; font-size: 1.05rem; 
            display: flex; align-items: center; justify-content: space-between; transition: 0.2s;
        }
        .card:hover { transform: translateX(5px); }
        .sub-perc { font-size: 0.9rem; color: var(--accent); background: #fff0ec; padding: 4px 10px; border-radius: 20px; margin-top: 5px; display: inline-block; }

        /* LIST ITEMS */
        .list-item { 
            background: white; padding: 1.2rem 1.5rem; margin-bottom: 0.8rem; 
            border-radius: 8px; display: flex; justify-content: space-between; align-items: center; 
            box-shadow: 0 2px 6px rgba(0,0,0,0.04); cursor: pointer; font-weight: 500; 
        }
        .list-item.locked { color: #888; background: #e9ecef; }

        /* BUTTONS */
        .btn { background-color: var(--accent); color: white; border: none; padding: 12px 28px; font-size: 1rem; font-weight: bold; border-radius: 30px; cursor: pointer; }
        .back-btn { background: none; border: none; color: var(--secondary); font-weight: bold; cursor: pointer; margin-bottom: 1rem; }

        /* 📱 LEONARDO.AI STYLE SIDEBAR (DRAWER) */
        .sidebar {
            position: fixed; top: 0; left: -300px; width: 280px; height: 100%;
            background-color: var(--dark); color: white; z-index: 2000;
            transition: 0.3s ease; padding: 20px; box-shadow: 5px 0 25px rgba(0,0,0,0.3);
            display: flex; flex-direction: column;
        }
        .sidebar.open { left: 0; }
        .sidebar-overlay {
            position: fixed; top: 0; left: 0; width: 100%; height: 100%;
            background: rgba(0,0,0,0.5); z-index: 1999; display: none;
        }
        .sidebar-overlay.show { display: block; }

        .sidebar-close { align-self: flex-end; background: none; border: none; color: #9ca3af; font-size: 1.5rem; cursor: pointer; }
        .sidebar-brand { font-size: 1.4rem; font-weight: bold; letter-spacing: 1px; color: white; margin-bottom: 20px; text-align: left; border-bottom: 1px solid #374151; padding-bottom: 10px; }
        
        /* PROFILE BOX INSIDE SIDEBAR */
        .profile-section { background: #1e293b; padding: 15px; border-radius: 12px; display: flex; align-items: center; justify-content: space-between; margin-bottom: 25px; }
        .profile-left { display: flex; align-items: center; gap: 12px; }
        .avatar { width: 40px; height: 40px; background: var(--accent); color: white; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-weight: bold; font-size: 1.2rem; }
        .profile-info { text-align: left; }
        .profile-name { font-weight: bold; font-size: 0.95rem; color: #f3f4f6; max-width: 120px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
        .profile-status { font-size: 0.75rem; color: #9ca3af; margin-top: 2px; }
        .user-total-badge { font-size: 0.85rem; font-weight: bold; color: var(--success); background: rgba(46, 196, 182, 0.1); padding: 4px 8px; border-radius: 8px; }

        /* SIDEBAR LINKS */
        .sidebar-menu { list-style: none; text-align: left; flex-grow: 1; }
        .sidebar-item { padding: 12px 15px; border-radius: 8px; margin-bottom: 8px; cursor: pointer; display: flex; align-items: center; gap: 12px; color: #9ca3af; font-weight: 500; transition: 0.2s; }
        .sidebar-item:hover, .sidebar-item.active-menu { background: #1e293b; color: white; }

        /* MODAL */
        .modal { display: none; position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.6); align-items: center; justify-content: center; z-index: 3000; }
        .modal-content { background: white; padding: 2rem; border-radius: 15px; text-align: center; max-width: 400px; margin: 1rem; color: var(--dark); }