:root {
    --bg-color-light: #f5f5f5;
    --text-color-light: #222;
    --bg-color-dark: #121212;
    --text-color-dark: #eee;

    --primary-color: #2a9d8f;
}

body {
    margin: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color-light);
    color: var(--text-color-light);
    transition: background-color 0.3s, color 0.3s;
}

body.dark {
    background-color: var(--bg-color-dark);
    color: var(--text-color-dark);
}

header {
    background-color: var(--primary-color);
    color: white;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
}

nav a {
    color: white;
    margin: 0 1rem;
    text-decoration: none;
    font-weight: 600;
}

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

.container {
    max-width: 900px;
    margin: 2rem auto;
    padding: 0 1rem;
}

h1, h2 {
    color: var(--primary-color);
}

button, select {
    padding: 0.4rem 0.8rem;
    margin-left: 1rem;
    font-size: 1rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}

button:hover, select:hover {
    opacity: 0.8;
}

footer {
    text-align: center;
    padding: 1rem;
    margin-top: 3rem;
    border-top: 1px solid #ccc;
    color: #888;
}

/* Responsive nav for smaller screens */
@media (max-width: 600px) {
    nav {
        width: 100%;
        margin-top: 0.5rem;
    }

    nav a {
        display: block;
        margin: 0.5rem 0;
    }

    header {
        flex-direction: column;
        align-items: flex-start;
    }
}