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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f5f7fa;
    color: #333;
    line-height: 1.6;
}

.container {
    max-width: 600px;
    margin: 0 auto;
    padding: 20px;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 15px;
    border-bottom: 2px solid #e0e0e0;
}

header h1 {
    font-size: 2.2rem;
    color: #2c3e50;
}

header a {
    color: #3498db;
    text-decoration: none;
    font-size: 0.9rem;
}

header a:hover {
    text-decoration: underline;
}

.input-section {
    display: flex;
    margin-bottom: 25px;
    gap: 10px;
}

#todo-input {
    flex: 1;
    padding: 12px 15px;
    border: 2px solid #ddd;
    border-radius: 4px;
    font-size: 1rem;
    outline: none;
    transition: border-color 0.3s;
}

#todo-input:focus {
    border-color: #3498db;
}

#add-btn {
    padding: 12px 20px;
    background-color: #2ecc71;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: background-color 0.3s;
}

#add-btn:hover {
    background-color: #27ae60;
}

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

.todo-item {
    display: flex;
    align-items: center;
    padding: 15px;
    background-color: white;
    border-radius: 6px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    margin-bottom: 12px;
    transition: transform 0.2s, box-shadow 0.2s;
}

.todo-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.15);
}

.todo-text {
    flex: 1;
    font-size: 1.1rem;
    padding: 0 15px;
    word-break: break-word;
}

.todo-text.completed {
    text-decoration: line-through;
    color: #7f8c8d;
}

.todo-actions {
    display: flex;
    gap: 8px;
}

.action-btn {
    padding: 8px 12px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.2s;
}

.complete-btn {
    background-color: #3498db;
    color: white;
}

.complete-btn:hover {
    background-color: #2980b9;
}

.delete-btn {
    background-color: #e74c3c;
    color: white;
}

.delete-btn:hover {
    background-color: #c0392b;
}

/* Responsive design */
@media (max-width: 600px) {
    .container {
        padding: 15px;
    }
    
    header {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }
    
    .input-section {
        flex-direction: column;
    }
    
    #add-btn {
        align-self: flex-end;
    }
    
    .todo-item {
        flex-wrap: wrap;
    }
    
    .todo-actions {
        width: 100%;
        justify-content: flex-end;
        margin-top: 10px;
    }
}