/* Base styles */
:root {
    --primary-color: #3498db;
    --secondary-color: #2ecc71;
    --text-color: #333;
    --bg-color: #f9f9f9;
    --card-bg: #fff;
    --header-bg: #fff;
    --footer-bg: #333;
    --footer-text: #fff;
    --border-radius: 8px;
    --box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

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

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

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header styles */
header {
    background-color: var(--header-bg);
    box-shadow: var(--box-shadow);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo h1 {
    font-size: 1.8rem;
    color: var(--primary-color);
}

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

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

nav ul li a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: var(--transition);
}

nav ul li a:hover, nav ul li a.active {
    color: var(--primary-color);
}

/* Button styles */
.btn {
    padding: 0.8rem 1.5rem;
    border: none;
    border-radius: var(--border-radius);
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.primary {
    background-color: var(--primary-color);
    color: white;
}

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

.secondary {
    background-color: transparent;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
}

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

/* Hero section */
.hero {
    padding: 5rem 0;
    text-align: center;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.hero p {
    font-size: 1.2rem;
    max-width: 700px;
    margin: 0 auto 2rem;
    color: #666;
}

.cta {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

/* Features section */
.features {
    padding: 5rem 0;
    background-color: var(--card-bg);
}

.features h2 {
    text-align: center;
    margin-bottom: 3rem;
    font-size: 2rem;
}

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

.feature-card {
    background-color: var(--card-bg);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    text-align: center;
    transition: var(--transition);
}

.feature-card:hover {
    transform: translateY(-5px);
}

.feature-card i {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.feature-card h3 {
    margin-bottom: 1rem;
}

/* Demo section */
.demo {
    padding: 5rem 0;
}

.demo h2 {
    text-align: center;
    margin-bottom: 3rem;
    font-size: 2rem;
}

.demo-container {
    max-width: 600px;
    margin: 0 auto;
    background-color: var(--card-bg);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}

.controls {
    display: flex;
    gap: 10px;
    margin-bottom: 1rem;
    justify-content: center;
}

input {
    padding: 0.7rem;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 1rem;
}

.message {
    padding: 1rem;
    background-color: #f5f5f5;
    border-radius: 4px;
    margin-top: 1rem;
}

/* Footer styles */
footer {
    background-color: var(--footer-bg);
    color: var(--footer-text);
    padding: 2rem 0;
    margin-top: 3rem;
}

footer .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.social-links {
    display: flex;
    gap: 1rem;
}

.social-links a {
    color: var(--footer-text);
    font-size: 1.2rem;
    transition: var(--transition);
}

.social-links a:hover {
    color: var(--primary-color);
}

.theme-toggle {
    margin-top: 1.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

#themeToggle {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    font-size: 1.2rem;
    padding: 0;
    display: flex;
    align-items: center;
    justify-content: center;
}

#message {
    margin-top: 1.5rem;
    padding: 1rem;
    border-radius: 4px;
    display: none;
    transition: background-color 0.3s;
}

/* Dark mode styles */
body.dark-mode {
    background-color: #1a1a1a;
    color: #f4f4f4;
}

body.dark-mode .container {
    background-color: #2c3e50;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

body.dark-mode h1 {
    color: #3498db;
}

body.dark-mode input {
    background-color: #34495e;
    color: white;
    border-color: #2c3e50;
}

body.dark-mode button {
    background-color: #e74c3c;
}

body.dark-mode button:hover {
    background-color: #c0392b;
}

/* Responsive styles */
@media (max-width: 768px) {
    nav ul {
        display: none;
    }
    
    .cta {
        flex-direction: column;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .feature-grid {
        grid-template-columns: 1fr;
    }
    
    footer .container {
        flex-direction: column;
        gap: 1rem;
    }
}