/* Base Styles */
:root {
    --primary-color: #3498db;
    --secondary-color: #2c3e50;
    --accent-color: #e74c3c;
    --light-bg: #f8f9fa;
    --dark-bg: #343a40;
    --text-color: #333;
    --light-text: #f8f9fa;
    --border-radius: 8px;
    --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Roboto', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: #fff;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

img {
    max-width: 100%;
    height: auto;
    border-radius: var(--border-radius);
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--accent-color);
}

ul {
    list-style: none;
}

/* Header Styles */
header {
    background-color: var(--secondary-color);
    color: var(--light-text);
    padding: 20px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--box-shadow);
}

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

.logo h1 {
    font-size: 1.8rem;
    font-weight: 700;
}

nav ul {
    display: flex;
}

nav ul li {
    margin-left: 20px;
}

nav ul li a {
    color: var(--light-text);
    font-weight: 500;
    padding: 5px 10px;
    border-radius: var(--border-radius);
}

nav ul li a:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--light-text);
    padding: 100px 0;
    text-align: center;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 20px;
    line-height: 1.2;
}

.hero p {
    font-size: 1.5rem;
    max-width: 800px;
    margin: 0 auto;
}

/* Section Styles */
.section {
    padding: 80px 0;
}

.section h2 {
    font-size: 2.5rem;
    margin-bottom: 40px;
    text-align: center;
    color: var(--secondary-color);
}

.section-intro {
    text-align: center;
    max-width: 800px;
    margin: 0 auto 40px;
    font-size: 1.2rem;
}

.alt-bg {
    background-color: var(--light-bg);
}

.content {
    display: flex;
    align-items: center;
    gap: 40px;
}

.text, .image {
    flex: 1;
}

.text p {
    margin-bottom: 20px;
    font-size: 1.1rem;
}

.full-width {
    flex: 0 0 100%;
}

/* Cards Section */
.cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 40px;
}

.card {
    background-color: #fff;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    padding: 30px;
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
}

.card-icon {
    width: 60px;
    height: 60px;
    margin: 0 auto 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--primary-color);
    border-radius: 50%;
}

.card-icon img {
    width: 30px;
    height: 30px;
}

.card h3 {
    text-align: center;
    margin-bottom: 20px;
    color: var(--secondary-color);
}

.card ul li {
    margin-bottom: 10px;
    position: relative;
    padding-left: 25px;
}

.card ul li:before {
    content: "✓";
    color: var(--primary-color);
    position: absolute;
    left: 0;
}

/* Challenges Section */
.challenges {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.challenge {
    background-color: #fff;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    padding: 25px;
}

.challenge h3 {
    color: var(--secondary-color);
    margin-bottom: 15px;
    font-size: 1.3rem;
}

/* Footer Styles */
footer {
    background-color: var(--dark-bg);
    color: var(--light-text);
    padding: 60px 0 20px;
}

.footer-content {
    display: flex;
    flex-wrap: wrap;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-info, .footer-references {
    flex: 1;
    min-width: 300px;
}

.footer-info h3, .footer-references h3 {
    margin-bottom: 20px;
    font-size: 1.5rem;
}

.footer-references ul li {
    margin-bottom: 10px;
}

.footer-references ul li a {
    color: var(--light-text);
    opacity: 0.8;
}

.footer-references ul li a:hover {
    opacity: 1;
    color: var(--primary-color);
}

.copyright {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

/* Responsive Styles */
@media (max-width: 992px) {
    .content {
        flex-direction: column;
    }
    
    .section {
        padding: 60px 0;
    }
    
    .hero {
        padding: 80px 0;
    }
    
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .hero p {
        font-size: 1.2rem;
    }
}

@media (max-width: 768px) {
    header .container {
        flex-direction: column;
    }
    
    .logo {
        margin-bottom: 15px;
    }
    
    nav ul {
        flex-wrap: wrap;
        justify-content: center;
    }
    
    nav ul li {
        margin: 5px 10px;
    }
    
    .section h2 {
        font-size: 2rem;
    }
    
    .cards {
        grid-template-columns: 1fr;
    }
    
    .challenges {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 2rem;
    }
    
    .section h2 {
        font-size: 1.8rem;
    }
    
    .card, .challenge {
        padding: 20px;
    }
}