:root {
    --primary-color: #4a90e2;
    --secondary-color: #f5f6fa;
    --text-color: #2d3436;
    --success-color: #00b894;
    --danger-color: #d63031;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Poppins', sans-serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
}

.app-container {
    background: white;
    border-radius: 20px;
    box-shadow: var(--shadow);
    width: 100%;
    max-width: 600px;
    padding: 2rem;
}

.header {
    text-align: center;
    margin-bottom: 2rem;
}

.header h1 {
    color: var(--text-color);
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

.header p {
    color: #636e72;
    font-size: 1rem;
}

.input-container {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
}

#new-task {
    flex: 1;
    padding: 1rem;
    border: 2px solid #dfe6e9;
    border-radius: 10px;
    font-size: 1rem;
    transition: var(--transition);
}

#new-task:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(74, 144, 226, 0.1);
}

.btn {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 1rem 1.5rem;
    border-radius: 10px;
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition);
}

.btn:hover {
    background: #357abd;
    transform: translateY(-2px);
}

.task-progress {
    margin-bottom: 2rem;
}

#progress-text {
    color: var(--text-color);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

#progress-bar {
    background: #dfe6e9;
    height: 8px;
    border-radius: 4px;
    overflow: hidden;
}

#progress-fill {
    background: var(--success-color);
    height: 100%;
    width: 0%;
    transition: var(--transition);
}

#task-list {
    list-style: none;
}

.task-item {
    background: var(--secondary-color);
    padding: 1rem;
    border-radius: 10px;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: var(--transition);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.task-item:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow);
    background: #eef2f7;
}

.task-item::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 4px;
    background: var(--primary-color);
    opacity: 0;
    transition: var(--transition);
}

.task-item:hover::before {
    opacity: 1;
}

.task-item.completed {
    background: #e8f5e9;
}

.task-item.completed::before {
    background: var(--success-color);
    opacity: 1;
}

.task-item.completed .task-text {
    text-decoration: line-through;
    color: #636e72;
}

.task-text {
    flex: 1;
    margin-right: 1rem;
    color: var(--text-color);
    transition: var(--transition);
}

.task-actions {
    display: flex;
    gap: 0.5rem;
    opacity: 0.7;
    transition: var(--transition);
}

.task-item:hover .task-actions {
    opacity: 1;
}

.delete-btn {
    background: var(--danger-color);
    color: white;
    border: none;
    padding: 0.5rem;
    border-radius: 5px;
    cursor: pointer;
    transition: var(--transition);
}

.delete-btn:hover {
    background: #c23616;
    transform: scale(1.1);
}

.complete-btn {
    background: var(--success-color);
    color: white;
    border: none;
    padding: 0.5rem;
    border-radius: 5px;
    cursor: pointer;
    transition: var(--transition);
}

.complete-btn:hover {
    background: #00a884;
}

@media (max-width: 480px) {
    .app-container {
        padding: 1.5rem;
    }
    
    .input-container {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
    }
}