:root {
    /* Base colors */
    --primary-color: #4a69bd; /* Deep blue */
    --accent-color: #78e08f; /* Soft green */
    --text-color: #34495e; /* Dark slate */
    --bg-color: #f7f7f7; /* Very light grey */
    --footer-bg-color: #2c3e50; /* Dark blue */
    --footer-text-color: #ecf0f1; /* Soft white */

    /* Dark theme colors */
    --dark-bg-color: #2c3e50;
    --dark-text-color: #ecf0f1;
    --dark-footer-bg-color: #34495e;
    --dark-footer-text-color: #95a5a6;
}

[data-theme="dark"] {
    --bg-color: var(--dark-bg-color);
    --text-color: var(--dark-text-color);
    --footer-bg-color: var(--dark-footer-bg-color);
    --footer-text-color: var(--dark-footer-text-color);
}

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

header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background-color: var(--footer-bg-color);
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    padding: 10px 0;
}

nav ul {
    list-style: none;
    padding: 0;
    display: flex;
    justify-content: center;
    margin: 0 auto;
}

nav ul li {
    margin: 0 20px;
}

nav ul li a {
    color: var(--footer-text-color);
    text-decoration: none;
    transition: color 0.2s ease-in-out, background-color 0.2s ease-in-out;
    padding: 5px 10px;
    border-radius: 5px;
}

nav ul li a:hover, nav ul li a:focus {
    color: var(--footer-text-color);
    background-color: var(--primary-color);
}

.hero {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 90vh;
    text-align: center;
    flex-direction: column;
}

.hero h1 {
    font-size: clamp(2rem, 5vw, 5rem);
}

button, .cta {
    background-color: var(--accent-color);
    color: var(--footer-bg-color);
    border: none;
    padding: 10px 30px;
    font-weight: bold;
    cursor: pointer;
    border-radius: 30px;
    transition: all 0.3s ease-in-out;
}

button:hover, .cta:hover {
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    transform: scale(1.05);
}

footer {
    background-color: var(--footer-bg-color);
    color: var(--footer-text-color);
    text-align: center;
    padding: 20px 0;
    transition: background-color 0.3s ease, color 0.3s ease;
}

footer p {
    margin: 0;
}

input[type="text"], input[type="email"], textarea {
    border: 1px solid var(--primary-color);
    padding: 10px;
    border-radius: 5px;
    width: 100%;
    box-sizing: border-box;
    transition: border 0.3s ease-in-out;
}

input[type="text"]:focus, input[type="email"]:focus, textarea:focus {
    border-color: var(--accent-color);
    outline: none;
}

@media (max-width: 768px) {
    nav ul {
        flex-direction: column;
    }

    nav ul li {
        margin: 10px 0;
    }
}

/* Responsive typography adjustments */
body {
    font-size: clamp(1rem, 2vw, 1.2rem);
}