:root {
    --primary-color: #2c3e50;
    --secondary-color: #34495e;
    --accent-color: #e74c3c;
    --text-color: #333;
    --bg-color: #f9f9f9;
    --white: #fff;
    --gray-light: #ecf0f1;
    --gray-dark: #7f8c8d;
    --font-main: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --spacing-unit: 1rem;
    --container-width: 1200px;
    --header-height: 70px;
    --shadow: 0 4px 6px rgba(0,0,0,0.1);
    --transition: all 0.3s ease;
}

/* Reset & Base */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font-main);
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

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

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

img {
    max-width: 100%;
    height: auto;
    display: block;
}

ul {
    list-style: none;
}

/* Accessibility */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    border: 0;
}

.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--accent-color);
    color: var(--white);
    padding: 8px;
    z-index: 100;
    transition: top 0.3s;
}

.skip-link:focus {
    top: 0;
}

/* Layout */
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 var(--spacing-unit);
}

/* Header */
header {
    background: var(--white);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
    height: var(--header-height);
    display: flex;
    align-items: center;
}

.header-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* Navigation */
.nav-menu {
    display: flex;
    gap: 2rem;
}

.nav-link {
    font-weight: 500;
    color: var(--secondary-color);
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: -4px;
    left: 0;
    background-color: var(--accent-color);
    transition: var(--transition);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.5rem;
    color: var(--primary-color);
}

/* Hero Section */
.hero {
    background: linear-gradient(rgba(44, 62, 80, 0.9), rgba(44, 62, 80, 0.8)), url('../img/img1.jpg') no-repeat center center/cover;
    color: var(--white);
    padding: 4rem 0;
    text-align: center;
    margin-bottom: 2rem;
}

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

.hero p {
    font-size: 1.2rem;
    max-width: 800px;
    margin: 0 auto;
}

/* Main Content */
main {
    flex: 1;
    padding: 2rem 0;
}

section {
    margin-bottom: 3rem;
}

.section-title {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    text-align: center;
    position: relative;
    padding-bottom: 0.5rem;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: var(--accent-color);
    margin: 0.5rem auto 0;
}

/* Cards Grid */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.card {
    background: var(--white);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0,0,0,0.1);
}

.card-img {
    height: 200px;
    object-fit: cover;
    width: 100%;
}

.card-content {
    padding: 1.5rem;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.card-title {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--secondary-color);
}

.card-meta {
    font-size: 0.85rem;
    color: var(--gray-dark);
    margin-bottom: 1rem;
    display: flex;
    justify-content: space-between;
}

.card-excerpt {
    margin-bottom: 1.5rem;
    flex: 1;
}

.btn {
    display: inline-block;
    padding: 0.6rem 1.2rem;
    background: var(--primary-color);
    color: var(--white);
    border-radius: 4px;
    text-align: center;
    font-weight: 500;
    border: none;
    cursor: pointer;
    align-self: flex-start;
}

.btn:hover {
    background: var(--accent-color);
    color: var(--white);
}

/* Article Page */
.article-header {
    text-align: center;
    margin-bottom: 2rem;
}

.article-meta {
    color: var(--gray-dark);
    margin-top: 0.5rem;
}

.article-content {
    background: var(--white);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: var(--shadow);
    max-width: 900px;
    margin: 0 auto;
}

.article-content h2 {
    color: var(--primary-color);
    margin: 1.5rem 0 1rem;
    border-bottom: 2px solid var(--gray-light);
    padding-bottom: 0.5rem;
}

.article-content h3 {
    color: var(--secondary-color);
    margin: 1.2rem 0 0.8rem;
}

.article-content p {
    margin-bottom: 1rem;
}

.article-content ul, .article-content ol {
    margin-bottom: 1rem;
    padding-left: 2rem;
    list-style: disc;
}

.article-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
}

.article-content th, .article-content td {
    padding: 0.75rem;
    border: 1px solid var(--gray-light);
    text-align: left;
}

.article-content th {
    background: var(--gray-light);
    font-weight: 600;
}

/* Related Posts */
.related-posts {
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--gray-light);
}

/* Footer */
footer {
    background: var(--primary-color);
    color: var(--white);
    padding: 3rem 0;
    margin-top: auto;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    margin-bottom: 1rem;
    color: var(--gray-light);
}

.footer-links li {
    margin-bottom: 0.5rem;
}

.footer-links a {
    color: var(--gray-light);
}

.footer-links a:hover {
    color: var(--white);
}

.copyright {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255,255,255,0.1);
    color: var(--gray-dark);
    font-size: 0.9rem;
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .mobile-menu-btn {
        display: block;
    }

    .nav-menu {
        position: fixed;
        top: var(--header-height);
        left: -100%;
        width: 100%;
        height: calc(100vh - var(--header-height));
        background: var(--white);
        flex-direction: column;
        padding: 2rem;
        transition: var(--transition);
        box-shadow: var(--shadow);
    }

    .nav-menu.active {
        left: 0;
    }

    .hero h1 {
        font-size: 2rem;
    }
    
    .article-content {
        padding: 1rem;
    }
}