:root {
            --primary-color: #4361ee;
            --secondary-color: #3f37c9;
            --success-color: #4cc9f0;
            --warning-color: #f72585;
            --dark-bg: #1e293b;
            --light-bg: #f8fafc;
            --card-bg: #ffffff;
            --text-primary: #1e293b;
            --text-secondary: #64748b;
            --border-color: #e2e8f0;
            --border-radius: 12px;
            --box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
            --transition: all 0.3s ease;
            --font-main: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }

        .dark {
            --primary-color: #536dfe;
            --secondary-color: #4a56e2;
            --success-color: #5ed1f5;
            --warning-color: #ff528f;
            --dark-bg: #0f172a;
            --light-bg: #1e293b;
            --card-bg: #1e293b;
            --text-primary: #f1f5f9;
            --text-secondary: #94a3b8;
            --border-color: #334155;
            --box-shadow: 0 4px 20px rgba(0, 0, 0, 0.25);
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: var(--font-main);
            background: linear-gradient(135deg, var(--light-bg) 0%, #e4edf5 100%);
            color: var(--text-primary);
            line-height: 1.6;
            padding: 20px;
            transition: var(--transition);
            min-height: 100vh;
        }

        .dark body {
            background: linear-gradient(135deg, var(--dark-bg) 0%, #0a0f1d 100%);
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
        }

        header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 20px 0;
            border-bottom: 1px solid var(--border-color);
            margin-bottom: 30px;
        }

        h1 {
            font-size: 2.5rem;
            font-weight: 800;
            background: linear-gradient(45deg, var(--primary-color), var(--success-color));
            -webkit-background-clip: text;
            background-clip: text;
            color: transparent;
            letter-spacing: -0.5px;
        }

        .controls {
            display: flex;
            gap: 15px;
        }

        .toggle-btn {
            background: var(--card-bg);
            border: 1px solid var(--border-color);
            width: 50px;
            height: 30px;
            border-radius: 15px;
            position: relative;
            cursor: pointer;
            box-shadow: var(--box-shadow);
            transition: var(--transition);
            display: flex;
            align-items: center;
            justify-content: center;
            font-weight: 600;
            color: var(--text-primary);
        }

        .toggle-btn::after {
            content: "";
            position: absolute;
            width: 26px;
            height: 26px;
            background: var(--primary-color);
            border-radius: 50%;
            left: 2px;
            transition: var(--transition);
        }

        .dark .toggle-btn::after {
            background: var(--warning-color);
            transform: translateX(20px);
        }

        .lang-toggle {
            background: var(--card-bg);
            border: 1px solid var(--border-color);
            padding: 8px 16px;
            border-radius: 20px;
            font-weight: 600;
            cursor: pointer;
            box-shadow: var(--box-shadow);
            transition: var(--transition);
            color: var(--text-primary);
        }

        .lang-toggle:hover {
            transform: translateY(-2px);
            box-shadow: 0 6px 25px rgba(0, 0, 0, 0.15);
        }

        .dark .lang-toggle:hover {
            box-shadow: 0 6px 25px rgba(0, 0, 0, 0.35);
        }

        .task-form {
            background: var(--card-bg);
            border-radius: var(--border-radius);
            padding: 25px;
            box-shadow: var(--box-shadow);
            margin-bottom: 30px;
            transition: var(--transition);
            border: 1px solid var(--border-color);
        }

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

        label {
            display: block;
            margin-bottom: 8px;
            font-weight: 600;
            color: var(--text-primary);
        }

        input, textarea, select {
            width: 100%;
            padding: 14px;
            border: 1px solid var(--border-color);
            border-radius: 10px;
            font-family: var(--font-main);
            font-size: 16px;
            transition: var(--transition);
            background: var(--card-bg);
            color: var(--text-primary);
        }

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

        .dark input:focus, .dark textarea:focus, .dark select:focus {
            box-shadow: 0 0 0 3px rgba(83, 109, 254, 0.3);
        }

        textarea {
            min-height: 100px;
            resize: vertical;
        }

        .datetime-group {
            display: flex;
            gap: 15px;
            flex-wrap: wrap;
        }

        .datetime-group div {
            flex: 1;
            min-width: 150px;
        }

        .days-selection {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(80px, 1fr));
            gap: 10px;
            margin-top: 10px;
            padding: 15px;
            background: rgba(67, 97, 238, 0.05);
            border-radius: 10px;
            border: 1px solid var(--border-color);
        }

        .dark .days-selection {
            background: rgba(83, 109, 254, 0.1);
            border-color: var(--border-color);
        }

        .day-checkbox {
            display: flex;
            flex-direction: column;
            align-items: center;
            cursor: pointer;
            padding: 8px;
            border-radius: 8px;
            transition: var(--transition);
            text-align: center;
        }

        .day-checkbox:hover {
            background: rgba(67, 97, 238, 0.1);
        }

        .dark .day-checkbox:hover {
            background: rgba(83, 109, 254, 0.2);
        }

        .day-checkbox input {
            width: auto;
            margin-right: 0;
            height: 20px;
            width: 20px;
            cursor: pointer;
            margin-bottom: 5px;
        }

        .day-label {
            margin-top: 5px;
            font-size: 14px;
            font-weight: 500;
            color: var(--text-primary);
        }

        button {
            background: linear-gradient(45deg, var(--primary-color), var(--secondary-color));
            color: white;
            border: none;
            padding: 14px 28px;
            border-radius: 10px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: var(--transition);
            width: 100%;
            box-shadow: 0 4px 15px rgba(67, 97, 238, 0.4);
        }

        button:hover {
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(67, 97, 238, 0.6);
        }

        button:active {
            transform: translateY(0);
        }

        .notification-area {
            position: fixed;
            top: 20px;
            right: 20px;
            z-index: 1000;
            display: flex;
            flex-direction: column;
            gap: 10px;
            max-width: 350px;
        }

        .notification {
            background: var(--card-bg);
            border-left: 4px solid var(--warning-color);
            border-radius: 8px;
            padding: 15px 20px;
            box-shadow: var(--box-shadow);
            display: flex;
            align-items: flex-start;
            gap: 10px;
            animation: slideIn 0.3s ease-out, fadeOut 0.5s ease-in 2.5s forwards;
            position: relative;
            overflow: hidden;
            border: 1px solid var(--border-color);
        }

        .notification::after {
            content: "";
            position: absolute;
            bottom: 0;
            left: 0;
            width: 100%;
            height: 4px;
            background: var(--warning-color);
            animation: progress 2.5s linear forwards;
        }

        @keyframes slideIn {
            from {
                transform: translateX(150%);
                opacity: 0;
            }
            to {
                transform: translateX(0);
                opacity: 1;
            }
        }

        @keyframes fadeOut {
            from {
                opacity: 1;
                transform: translateX(0);
            }
            to {
                opacity: 0;
                transform: translateX(150%);
            }
        }

        @keyframes progress {
            from {
                width: 100%;
            }
            to {
                width: 0%;
            }
        }

        .notification-icon {
            font-size: 20px;
            margin-top: 2px;
        }

        .notification-content h3 {
            font-size: 18px;
            margin-bottom: 5px;
            color: var(--text-primary);
        }

        .notification-content p {
            font-size: 14px;
            color: var(--text-secondary);
        }

        .task-list {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
            gap: 25px;
        }

        .task-card {
            background: var(--card-bg);
            border-radius: var(--border-radius);
            padding: 20px;
            box-shadow: var(--box-shadow);
            transition: var(--transition);
            border-left: 4px solid var(--primary-color);
            position: relative;
            overflow: hidden;
            border: 1px solid var(--border-color);
        }

        .task-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 10px 30px rgba(0, 0, 0, 0.12);
        }

        .dark .task-card:hover {
            box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
        }

        .task-card::before {
            content: "";
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 4px;
            background: linear-gradient(90deg, var(--primary-color), var(--success-color));
        }

        .task-header {
            display: flex;
            justify-content: space-between;
            align-items: flex-start;
            margin-bottom: 15px;
            padding-bottom: 15px;
            border-bottom: 1px solid var(--border-color);
        }

        .task-title {
            font-size: 1.4rem;
            font-weight: 700;
            margin-bottom: 5px;
            color: var(--text-primary);
        }

        .task-days {
            display: flex;
            flex-wrap: wrap;
            gap: 5px;
            margin: 8px 0;
        }

        .day-badge {
            background: rgba(67, 97, 238, 0.15);
            color: var(--primary-color);
            padding: 3px 8px;
            border-radius: 12px;
            font-size: 12px;
            font-weight: 500;
        }

        .dark .day-badge {
            background: rgba(83, 109, 254, 0.2);
            color: var(--primary-color);
        }

        .task-time {
            color: var(--primary-color);
            font-weight: 600;
            font-size: 0.95rem;
            margin-top: 5px;
            display: flex;
            align-items: center;
            gap: 5px;
        }

        .task-description {
            color: var(--text-secondary);
            margin-bottom: 20px;
            line-height: 1.5;
        }

        .delete-btn {
            background: linear-gradient(45deg, #ff5252, #f44336);
            color: white;
            border: none;
            width: 36px;
            height: 36px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
            transition: var(--transition);
            position: absolute;
            top: 15px;
            right: 15px;
            font-weight: bold;
            box-shadow: 0 2px 10px rgba(244, 67, 54, 0.3);
            z-index: 10;
        }

        .delete-btn:hover {
            transform: scale(1.1);
            box-shadow: 0 4px 15px rgba(244, 67, 54, 0.4);
            background: linear-gradient(45deg, #ff3d3d, #e53935);
        }

        .empty-state {
            grid-column: 1 / -1;
            text-align: center;
            padding: 40px 20px;
            color: var(--text-secondary);
        }

        .empty-state svg {
            width: 100px;
            height: 100px;
            margin-bottom: 20px;
            color: var(--primary-color);
            opacity: 0.7;
        }

        .empty-state p {
            font-size: 1.2rem;
            max-width: 500px;
            margin: 0 auto;
        }

        .theme-icon {
            font-size: 18px;
        }

        .dark .theme-icon.sun {
            display: none;
        }

        .theme-icon.moon {
            display: none;
        }

        .dark .theme-icon.moon {
            display: inline;
        }

        .dark .theme-icon.sun {
            display: inline;
        }

        .app-version {
            position: fixed;
            bottom: 15px;
            right: 15px;
            background: var(--card-bg);
            color: var(--text-secondary);
            padding: 5px 10px;
            border-radius: 20px;
            font-size: 12px;
            box-shadow: var(--box-shadow);
            border: 1px solid var(--border-color);
            z-index: 100;
        }

        /* Responsive Design */
        @media (max-width: 768px) {
            .datetime-group {
                flex-direction: column;
            }
            
            header {
                flex-direction: column;
                gap: 20px;
                text-align: center;
            }
            
            .controls {
                width: 100%;
                justify-content: center;
            }
            
            .task-list {
                grid-template-columns: 1fr;
            }
            
            .notification-area {
                left: 20px;
                right: 20px;
                max-width: 100%;
            }
            
            .days-selection {
                grid-template-columns: repeat(auto-fill, minmax(60px, 1fr));
            }
        }

        @media (max-width: 480px) {
            .container {
                padding: 0 15px;
            }
            
            h1 {
                font-size: 2rem;
            }
            
            .task-form {
                padding: 20px;
            }
            
            input, textarea, select, button {
                padding: 12px;
            }
            
            .days-selection {
                grid-template-columns: repeat(auto-fill, minmax(50px, 1fr));
            }
            
            .day-label {
                font-size: 12px;
            }
            
            .controls {
                flex-direction: column;
                align-items: center;
            }
            
            .toggle-btn {
                width: 100%;
                max-width: 200px;
            }
        }

        /* RTL Support */
        [dir="rtl"] {
            direction: rtl;
            text-align: right;
        }

        [dir="rtl"] .controls {
            flex-direction: row-reverse;
        }

        [dir="rtl"] .datetime-group {
            flex-direction: column;
        }

        [dir="rtl"] .task-header {
            flex-direction: row-reverse;
        }

        [dir="rtl"] .delete-btn {
            right: auto;
            left: 15px;
        }

        [dir="rtl"] .notification {
            flex-direction: row-reverse;
            text-align: right;
        }

        [dir="rtl"] .notification::after {
            left: auto;
            right: 0;
        }

        [dir="rtl"] .task-card::before {
            left: auto;
            right: 0;
        }

        [dir="rtl"] .task-card {
            border-left: none;
            border-right: 4px solid var(--primary-color);
        }
        
        [dir="rtl"] .day-checkbox {
            flex-direction: column-reverse;
        }
        
        [dir="rtl"] .task-time {
            flex-direction: row-reverse;
        }