:root {
            --primary: #4361ee;
            --primary-dark: #3a56d4;
            --secondary: #7209b7;
            --accent: #f72585;
            --success: #4cc9f0;
            --work-color: #4361ee;
            --break-color: #4cc9f0;
            --long-break-color: #7209b7;
            --card-bg: #ffffff;
            --shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
            --radius: 16px;
            --transition: all 0.3s ease;
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Poppins', sans-serif;
        }

        body {
            background: linear-gradient(135deg, #f5f7fa 0%, #e4edf5 100%);
            color: #212529;
            line-height: 1.6;
            min-height: 100vh;
            padding: 20px;
            transition: background 0.5s ease;
        }

        body.work-mode {
            background: linear-gradient(135deg, #f0f4ff 0%, #e6f0ff 100%);
        }

        body.break-mode {
            background: linear-gradient(135deg, #f0f9ff 0%, #e6f7ff 100%);
        }

        body.long-break-mode {
            background: linear-gradient(135deg, #f8f0ff 0%, #f0e6ff 100%);
        }

        .container {
            max-width: 1000px;
            margin: 0 auto;
        }

        header {
            text-align: center;
            margin-bottom: 40px;
            padding: 20px;
        }

        h1 {
            font-size: 2.8rem;
            margin-bottom: 15px;
            background: linear-gradient(90deg, var(--primary), var(--secondary));
            -webkit-background-clip: text;
            background-clip: text;
            color: transparent;
            font-weight: 700;
            letter-spacing: -0.5px;
        }

        .subtitle {
            font-size: 1.2rem;
            color: #6c757d;
            max-width: 700px;
            margin: 0 auto 25px;
            font-weight: 400;
        }

        .main-content {
            display: grid;
            grid-template-columns: 1fr;
            gap: 30px;
        }

        @media (min-width: 992px) {
            .main-content {
                grid-template-columns: 1fr 1fr;
            }
        }

        .card {
            background: var(--card-bg);
            border-radius: var(--radius);
            box-shadow: var(--shadow);
            padding: 30px;
            transition: var(--transition);
            position: relative;
            overflow: hidden;
        }

        .card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 5px;
            background: linear-gradient(90deg, var(--primary), var(--secondary));
        }

        .card:hover {
            transform: translateY(-8px);
            box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
        }

        .card-header {
            display: flex;
            align-items: center;
            margin-bottom: 25px;
            padding-bottom: 20px;
            border-bottom: 1px solid rgba(0, 0, 0, 0.05);
        }

        .card-icon {
            width: 60px;
            height: 60px;
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            margin-right: 20px;
            color: white;
            font-size: 1.5rem;
            box-shadow: 0 4px 10px rgba(67, 97, 238, 0.3);
        }

        .card-title {
            font-size: 1.6rem;
            font-weight: 600;
            color: #212529;
        }

        .card-description {
            color: #6c757d;
            font-size: 0.95rem;
            margin-top: 5px;
        }

        /* Timer Styles */
        .timer-container {
            text-align: center;
            margin: 20px 0;
        }

        .timer-display {
            font-size: 5rem;
            font-weight: 700;
            margin: 20px 0;
            color: var(--primary);
            text-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
            transition: color 0.5s ease;
        }

        .timer-mode {
            font-size: 1.5rem;
            font-weight: 600;
            margin-bottom: 10px;
            color: #6c757d;
            text-transform: uppercase;
            letter-spacing: 2px;
        }

        .progress-ring {
            margin: 0 auto 30px;
        }

        .progress-ring-circle {
            transition: stroke-dashoffset 0.5s ease;
            transform: rotate(-90deg);
            transform-origin: 50% 50%;
        }

        /* Controls */
        .timer-controls {
            display: flex;
            justify-content: center;
            gap: 15px;
            margin: 30px 0;
        }

        .btn {
            padding: 14px 24px;
            border: none;
            border-radius: 10px;
            font-weight: 600;
            cursor: pointer;
            transition: var(--transition);
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 8px;
            font-size: 1rem;
            min-width: 140px;
        }

        .btn-primary {
            background: var(--primary);
            color: white;
            box-shadow: 0 4px 12px rgba(67, 97, 238, 0.3);
        }

        .btn-primary:hover {
            background: var(--primary-dark);
            transform: translateY(-2px);
            box-shadow: 0 6px 15px rgba(67, 97, 238, 0.4);
        }

        .btn-secondary {
            background: #e9ecef;
            color: #212529;
        }

        .btn-secondary:hover {
            background: #dee2e6;
            transform: translateY(-2px);
        }

        .btn-accent {
            background: var(--accent);
            color: white;
            box-shadow: 0 4px 12px rgba(247, 37, 133, 0.3);
        }

        .btn-accent:hover {
            background: #e11574;
            transform: translateY(-2px);
            box-shadow: 0 6px 15px rgba(247, 37, 133, 0.4);
        }

        .btn-success {
            background: var(--success);
            color: white;
            box-shadow: 0 4px 12px rgba(76, 201, 240, 0.3);
        }

        .btn-success:hover {
            background: #3ab3d9;
            transform: translateY(-2px);
            box-shadow: 0 6px 15px rgba(76, 201, 240, 0.4);
        }

        /* Settings */
        .settings-group {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 20px;
            margin-bottom: 25px;
        }

        @media (max-width: 576px) {
            .settings-group {
                grid-template-columns: 1fr;
            }
        }

        .input-group {
            margin-bottom: 20px;
        }

        label {
            display: block;
            margin-bottom: 10px;
            font-weight: 500;
            color: #212529;
            font-size: 1rem;
        }

        input, select {
            width: 100%;
            padding: 14px 16px;
            border: 1.5px solid #e1e5eb;
            border-radius: 10px;
            font-size: 1rem;
            transition: var(--transition);
            background-color: #fff;
            color: #212529;
        }

        input:focus, select:focus {
            outline: none;
            border-color: var(--primary);
            box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.2);
        }

        .checkbox-group {
            display: flex;
            align-items: center;
            margin-bottom: 15px;
        }

        .checkbox-group input {
            width: auto;
            margin-right: 10px;
        }

        .checkbox-group label {
            margin-bottom: 0;
            font-weight: 400;
        }

        /* Stats */
        .stats-container {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
            gap: 15px;
            margin-top: 25px;
        }

        .stat-item {
            background: white;
            border-radius: 10px;
            padding: 15px;
            text-align: center;
            box-shadow: 0 3px 10px rgba(0, 0, 0, 0.05);
        }

        .stat-value {
            font-size: 1.8rem;
            font-weight: 700;
            color: var(--secondary);
            margin-bottom: 5px;
        }

        .stat-label {
            font-size: 0.85rem;
            color: #6c757d;
            text-transform: uppercase;
            letter-spacing: 0.5px;
        }

        /* Task List */
        .task-input-container {
            display: flex;
            gap: 10px;
            margin-bottom: 20px;
        }

        .task-input {
            flex: 1;
        }

        .task-list {
            max-height: 300px;
            overflow-y: auto;
            border-radius: 10px;
            background: #f8f9fa;
            padding: 10px;
        }

        .task-item {
            display: flex;
            align-items: center;
            padding: 15px;
            border-bottom: 1px solid #e9ecef;
            transition: var(--transition);
        }

        .task-item:hover {
            background: white;
            border-radius: 8px;
        }

        .task-item:last-child {
            border-bottom: none;
        }

        .task-checkbox {
            margin-right: 15px;
        }

        .task-text {
            flex: 1;
            font-weight: 500;
        }

        .task-completed .task-text {
            text-decoration: line-through;
            color: #6c757d;
        }

        .task-actions {
            display: flex;
            gap: 10px;
        }

        .task-action-btn {
            background: none;
            border: none;
            color: #6c757d;
            cursor: pointer;
            transition: var(--transition);
        }

        .task-action-btn:hover {
            color: var(--primary);
        }

        /* History */
        .history-list {
            max-height: 250px;
            overflow-y: auto;
            border-radius: 10px;
            background: #f8f9fa;
            padding: 10px;
        }

        .history-item {
            display: flex;
            justify-content: space-between;
            padding: 15px;
            border-bottom: 1px solid #e9ecef;
            font-size: 0.95rem;
            transition: var(--transition);
        }

        .history-item:hover {
            background: white;
            border-radius: 8px;
        }

        .history-item:last-child {
            border-bottom: none;
        }

        .history-mode {
            color: #212529;
            font-weight: 500;
        }

        .history-time {
            color: var(--primary);
            font-weight: 600;
        }

        .history-date {
            color: #6c757d;
            font-size: 0.85rem;
            margin-top: 5px;
            width: 100%;
        }

        footer {
            text-align: center;
            margin-top: 60px;
            padding: 25px;
            color: #6c757d;
            font-size: 0.95rem;
            border-top: 1px solid rgba(0, 0, 0, 0.05);
        }

        .feature-highlights {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            gap: 25px;
            margin-top: 50px;
        }

        .feature {
            display: flex;
            align-items: center;
            background: var(--card-bg);
            padding: 20px;
            border-radius: 12px;
            box-shadow: 0 3px 15px rgba(0, 0, 0, 0.05);
            transition: var(--transition);
        }

        .feature:hover {
            transform: translateY(-5px);
            box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
        }

        .feature-icon {
            width: 50px;
            height: 50px;
            background: rgba(67, 97, 238, 0.1);
            border-radius: 12px;
            display: flex;
            align-items: center;
            justify-content: center;
            margin-right: 20px;
            color: var(--primary);
            font-size: 1.3rem;
        }

        .feature-text {
            font-weight: 500;
            font-size: 1.05rem;
        }

        /* Responsive adjustments */
        @media (max-width: 768px) {
            h1 {
                font-size: 2.2rem;
            }
            
            .card {
                padding: 25px 20px;
            }
            
            .main-content {
                gap: 25px;
            }
            
            .timer-display {
                font-size: 3.5rem;
            }
            
            .btn {
                min-width: 120px;
                padding: 12px 20px;
            }
        }

        @media (max-width: 576px) {
            h1 {
                font-size: 1.9rem;
            }
            
            .card-header {
                flex-direction: column;
                text-align: center;
            }
            
            .card-icon {
                margin-right: 0;
                margin-bottom: 15px;
            }
            
            .timer-controls {
                flex-direction: column;
            }
            
            .btn {
                width: 100%;
            }
        }

        /* Custom scrollbar */
        ::-webkit-scrollbar {
            width: 8px;
        }

        ::-webkit-scrollbar-track {
            background: #f1f1f1;
            border-radius: 10px;
        }

        ::-webkit-scrollbar-thumb {
            background: var(--primary);
            border-radius: 10px;
        }

        ::-webkit-scrollbar-thumb:hover {
            background: var(--primary-dark);
        }

        /* Notification styles */
        .notification {
            position: fixed;
            top: 20px;
            right: 20px;
            background: white;
            padding: 15px 20px;
            border-radius: 10px;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
            display: flex;
            align-items: center;
            gap: 10px;
            transform: translateX(150%);
            transition: transform 0.3s ease;
            z-index: 1000;
        }

        .notification.show {
            transform: translateX(0);
        }

        .notification-icon {
            width: 30px;
            height: 30px;
            background: var(--primary);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
        }

        /* Mode indicators */
        .mode-indicator {
            display: inline-block;
            width: 12px;
            height: 12px;
            border-radius: 50%;
            margin-right: 8px;
        }

        .mode-work {
            background: var(--work-color);
        }

        .mode-break {
            background: var(--break-color);
        }

        .mode-long-break {
            background: var(--long-break-color);
        }