:root {
    --primary-color: #1a237e;
    --secondary-color: #5c6bc0;
    --accent-color: #ffc107;
    --text-color: #333;
    --bg-color: #f5f5f5;

    /* Dark mode variables */
    --dark-primary-color: #9fa8da;
    --dark-secondary-color: #7986cb;
    --dark-accent-color: #ffca28;
    --dark-text-color: #e0e0e0;
    --dark-bg-color: #212121;
}

body.dark-mode {
    --primary-color: var(--dark-primary-color);
    --secondary-color: var(--dark-secondary-color);
    --accent-color: var(--dark-accent-color);
    --text-color: var(--dark-text-color);
    --bg-color: var(--dark-bg-color);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
}

header {
    background-color: #fff;
    padding: 1rem 2rem;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 100;
}

body.dark-mode header {
    background-color: var(--dark-bg-color);
    box-shadow: 0 2px 5px rgba(0,0,0,0.3);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

nav ul {
    list-style: none;
    display: flex;
}

nav ul li {
    margin-left: 1.5rem;
}

nav ul li a {
    text-decoration: none;
    color: var(--primary-color);
    font-weight: bold;
    transition: color 0.3s ease;
}

nav ul li a:hover {
    color: var(--secondary-color);
}

main {
    padding-top: 60px; /* Adjust for fixed header */
}

section {
    padding: 4rem 2rem;
    text-align: center;
}

#hero {
    background: linear-gradient(to right, var(--primary-color), var(--secondary-color));
    color: var(--text-color);
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
}

#hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
}

#hero p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
}

.cta-button {
    background-color: var(--accent-color);
    color: var(--text-color);
    padding: 1rem 2rem;
    text-decoration: none;
    border-radius: 5px;
    font-weight: bold;
    transition: background-color 0.3s ease;
}

.cta-button:hover {
    background-color: #ffca28;
}

#about h2, #services h2, #contact h2 {
    font-size: 2rem;
    margin-bottom: 2rem;
    color: var(--primary-color);
}

.service-cards {
    display: flex;
    justify-content: space-around;
    flex-wrap: wrap;
    gap: 1.5rem;
    margin-top: 2rem;
}

.card {
    background-color: #fff;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    flex-basis: 30%;
    text-align: left;
}

body.dark-mode .card {
    background-color: #424242;
    box-shadow: 0 4px 8px rgba(0,0,0,0.3);
}

.card h3 {
    color: var(--secondary-color);
    margin-bottom: 1rem;
}

#contact form {
    max-width: 600px;
    margin: 2rem auto;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

#contact input, #contact textarea {
    padding: 1rem;
    border: 1px solid #ccc;
    border-radius: 5px;
    background-color: var(--bg-color);
    color: var(--text-color);
}

body.dark-mode #contact input,
body.dark-mode #contact textarea {
    border: 1px solid #555;
    background-color: #333;
    color: var(--dark-text-color);
}

#contact button {
    background-color: var(--primary-color);
    color: #fff;
    padding: 1rem;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

#contact button:hover {
    background-color: var(--secondary-color);
}

footer {
    text-align: center;
    padding: 2rem;
    background-color: #333;
    color: #fff;
}

body.dark-mode footer {
    background-color: #1a1a1a;
    color: var(--dark-text-color);
}

/* Theme Toggle Button Style */
#theme-toggle {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 5px;
    cursor: pointer;
    margin-left: 1.5rem;
    transition: background-color 0.3s ease;
}

#theme-toggle:hover {
    background-color: var(--secondary-color);
}

@media (max-width: 768px) {
    nav ul {
        display: none; /* Simple responsive nav */
    }
    .card {
        flex-basis: 100%;
    }
}