:root {
    --primary-blue: #1e3a8a;
    --secondary-blue: #3b82f6;
    --light-blue: #dbeafe;
    --text-dark: #1f2937;
    --text-medium: #4b5563;
    --text-light: #6b7280;
    --background: #ffffff;
    --border: #e5e7eb;
}

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

body {
    font-family: 'Georgia', 'Times New Roman', serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--background);
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 20px;
}

header {
    background: linear-gradient(135deg, var(--primary-blue), var(--secondary-blue));
    color: white;
    padding: 60px 0;
    text-align: center;
}

h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 10px;
    letter-spacing: -0.02em;
}

.subtitle {
    font-size: 1.3rem;
    font-weight: 300;
    opacity: 0.9;
    font-family: 'Arial', sans-serif;
    text-align: center;
    color: white;
}

main {
    padding: 60px 0;
}

.section {
    margin-bottom: 50px;
}

h2 {
    font-size: 2rem;
    color: var(--primary-blue);
    margin-bottom: 20px;
    border-bottom: 3px solid var(--light-blue);
    padding-bottom: 10px;
}

h3 {
    font-size: 1.4rem;
    color: var(--secondary-blue);
    margin-bottom: 15px;
    margin-top: 30px;
}

p {
    margin-bottom: 15px;
    font-size: 1.1rem;
    text-align: justify;
    color: var(--text-medium);
}

.highlight-box {
    background-color: var(--light-blue);
    border-left: 4px solid var(--secondary-blue);
    padding: 25px;
    margin: 30px 0;
    border-radius: 0 8px 8px 0;
}

.dataset-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 30px;
}

.dataset-card {
    border: 2px solid var(--border);
    border-radius: 8px;
    padding: 25px;
    background-color: #fafafa;
}

.dataset-card h4 {
    color: var(--primary-blue);
    font-size: 1.2rem;
    margin-bottom: 15px;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 20px;
    margin: 30px 0;
}

.stat-item {
    text-align: center;
    padding: 20px;
    background-color: var(--light-blue);
    border-radius: 8px;
}

.stat-number {
    font-size: 2rem;
    font-weight: bold;
    color: var(--primary-blue);
    display: block;
}

.stat-label {
    font-size: 0.9rem;
    color: var(--text-medium);
    margin-top: 5px;
}

.contact-form {
    background-color: #f8fafc;
    border: 2px solid var(--border);
    border-radius: 8px;
    padding: 30px;
    margin-top: 30px;
}

.form-group {
    margin-bottom: 20px;
}

label {
    display: block;
    margin-bottom: 5px;
    font-weight: 600;
    color: var(--text-dark);
}

input[type="text"],
input[type="email"],
select,
textarea {
    width: 100%;
    padding: 12px;
    border: 2px solid var(--border);
    border-radius: 4px;
    font-size: 1rem;
    font-family: inherit;
    transition: border-color 0.3s ease;
}

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

textarea {
    resize: vertical;
    min-height: 120px;
}

.btn {
    background-color: var(--primary-blue);
    color: white;
    padding: 12px 30px;
    border: none;
    border-radius: 4px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.btn:hover {
    background-color: var(--secondary-blue);
}

footer {
    background-color: var(--primary-blue);
    color: white;
    text-align: center;
    padding: 30px 0;
    margin-top: 60px;
}

.footer-content {
    font-size: 0.9rem;
    color: white;
}

.footer-content p {
    color: white !important;
}

/* Responsive Design */
@media (max-width: 768px) {
    h1 {
        font-size: 2.2rem;
    }
    
    .subtitle {
        font-size: 1.1rem;
    }
    
    .container {
        padding: 0 15px;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Vocabulary Section Styles */
.vocabulary-section {
    margin-top: 30px;
}

.search-container {
    margin-bottom: 30px;
}

.search-input {
    width: 100%;
    padding: 15px;
    border: 2px solid var(--border);
    border-radius: 8px;
    font-size: 1.1rem;
    margin-bottom: 20px;
    transition: border-color 0.3s ease;
}

.search-input:focus {
    outline: none;
    border-color: var(--secondary-blue);
}

.category-filters {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 20px;
}

.filter-btn {
    padding: 8px 16px;
    border: 2px solid var(--border);
    background-color: white;
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-medium);
}

.filter-btn:hover {
    border-color: var(--secondary-blue);
    color: var(--secondary-blue);
}

.filter-btn.active {
    background-color: var(--secondary-blue);
    border-color: var(--secondary-blue);
    color: white;
}

.vocabulary-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 15px;
    max-height: 600px;
    overflow-y: auto;
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 20px;
    background-color: #fafafa;
}

.vocabulary-item {
    background-color: white;
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 12px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: box-shadow 0.2s ease;
}

.vocabulary-item:hover {
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.15);
}

.vocabulary-id {
    background-color: var(--light-blue);
    color: var(--primary-blue);
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 0.8rem;
    font-weight: bold;
    min-width: 35px;
    text-align: center;
}

.vocabulary-label {
    flex: 1;
    margin-left: 12px;
    font-size: 0.95rem;
    color: var(--text-dark);
}

@media (max-width: 768px) {
    .category-filters {
        justify-content: center;
    }
    
    .filter-btn {
        font-size: 0.8rem;
        padding: 6px 12px;
    }
    
    .vocabulary-grid {
        grid-template-columns: 1fr;
        max-height: 500px;
    }
}