/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #4a6fa5;
    --secondary-color: #166088;
    --accent-color: #4cb5ae;
    --light-color: #f8f9fa;
    --dark-color: #343a40;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --gray-color: #6c757d;
    --light-gray: #e9ecef;
    --border-radius: 4px;
    --box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: var(--dark-color);
    background-color: #f5f5f5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 15px;
}

/* Header and Navigation */
.navbar {
    background-color: var(--primary-color);
    padding: 1rem 0;
    box-shadow: var(--box-shadow);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 15px;
}

.nav-brand {
    color: white;
    text-decoration: none;
    font-size: 1.5rem;
    font-weight: bold;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-link {
    color: white;
    text-decoration: none;
    transition: var(--transition);
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
}

.nav-link:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

.nav-item.current .nav-link {
    background-color: rgba(255, 255, 255, 0.2);
}

.hamburger {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background-color: white;
    margin: 3px 0;
    transition: var(--transition);
}

/* Main content */
main {
    flex: 1;
    padding: 2rem 0;
}

.todo-section {
    background-color: white;
    border-radius: 8px;
    padding: 2rem;
    box-shadow: var(--box-shadow);
    max-width: 600px;
    margin: 0 auto;
}

.todo-section h1 {
    margin-bottom: 1.5rem;
    color: var(--secondary-color);
    text-align: center;
}

.todo-form {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

#todoInput {
    flex: 1;
    padding: 0.75rem;
    border: 1px solid var(--light-gray);
    border-radius: var(--border-radius);
    font-size: 1rem;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 1rem;
    transition: var(--transition);
}

.btn-primary:hover {
    background-color: var(--secondary-color);
}

.filter-options {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    justify-content: center;
}

.filter-btn {
    padding: 0.5rem 1rem;
    border: 1px solid var(--light-gray);
    background-color: white;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
}

.filter-btn.active,
.filter-btn:hover {
    background-color: var(--primary-color);
    color: white;
}

.todo-list {
    list-style: none;
    margin-bottom: 1.5rem;
}

.todo-item {
    display: flex;
    align-items: center;
    padding: 0.75rem;
    border-bottom: 1px solid var(--light-gray);
    transition: var(--transition);
}

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

.todo-item:hover {
    background-color: var(--light-gray);
}

.todo-checkbox {
    margin-right: 1rem;
    width: 20px;
    height: 20px;
    cursor: pointer;
}

.todo-text {
    flex: 1;
    word-break: break-word;
}

.todo-item.completed .todo-text {
    text-decoration: line-through;
    color: var(--gray-color);
}

.delete-btn {
    background-color: transparent;
    border: none;
    color: var(--danger-color);
    cursor: pointer;
    padding: 0.25rem 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.delete-btn:hover {
    background-color: var(--danger-color);
    color: white;
}

.empty-state {
    text-align: center;
    padding: 2rem;
    color: var(--gray-color);
}

/* Page content styles */
.page-content {
    background-color: white;
    border-radius: 8px;
    padding: 2rem;
    box-shadow: var(--box-shadow);
}

.page-content h1 {
    margin-bottom: 1.5rem;
    color: var(--secondary-color);
}

.feature-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
}

.feature {
    background-color: var(--light-gray);
    padding: 1.5rem;
    border-radius: var(--border-radius);
}

.feature h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

/* Contact form styles */
.contact-form {
    margin: 2rem 0;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: bold;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--light-gray);
    border-radius: var(--border-radius);
    font-size: 1rem;
}

.contact-info {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid var(--light-gray);
}

/* Footer */
footer {
    background-color: var(--dark-color);
    color: white;
    padding: 1.5rem 0;
    margin-top: auto;
}

footer .container {
    text-align: center;
}

/* Responsive design */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: var(--primary-color);
        width: 100%;
        text-align: center;
        transition: var(--transition);
        box-shadow: 0 10px 27px rgba(0, 0, 0, 0.05);
        padding: 2rem 0;
        gap: 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .nav-item {
        margin: 1rem 0;
    }
    
    .todo-form {
        flex-direction: column;
    }
    
    .filter-options {
        flex-wrap: wrap;
    }
}