/* === Общие сбросы и переменные === */
:root {
    --dark-blue: #0d2b4e;
    --accent: #1a9c9a;
    --accent-hover: #157a78;
    --text: #333;
    --light-bg: #f8f9fa;
    --white: #ffffff;
    --border-radius: 8px;
    --shadow: 0 4px 6px rgba(0,0,0,0.05), 0 1px 3px rgba(0,0,0,0.1);
    --transition: 0.2s ease;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    color: var(--text);
    line-height: 1.6;
    background: var(--white);
}

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

.section-padding {
    padding: 80px 0;
}

.text-center { text-align: center; }

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

/* Кнопки */
.btn {
    display: inline-block;
    padding: 12px 28px;
    border-radius: var(--border-radius);
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    border: none;
    transition: all var(--transition);
    text-align: center;
}

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

.btn-outline {
    border: 2px solid var(--accent);
    color: var(--accent);
    background: transparent;
}
.btn-outline:hover {
    background: var(--accent);
    color: #fff;
}

.btn-lg {
    padding: 16px 36px;
    font-size: 1.1rem;
}

/* Шапка */
.site-header {
    background: var(--dark-blue);
    color: #fff;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow);
}
.header-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
}

.logo {
    display: flex;
    flex-direction: column;
    color: #fff;
    text-decoration: none;
}
.logo-text {
    font-size: 1.8rem;
    font-weight: 700;
    line-height: 1;
}
.logo-sub {
    font-size: 0.8rem;
    font-weight: 400;
    opacity: 0.8;
}

.main-nav {
    display: flex;
    align-items: center;
    gap: 20px;
}

.nav-list {
    display: flex;
    list-style: none;
    gap: 20px;
}
.nav-list a {
    color: #fff;
    font-weight: 500;
    padding: 5px 0;
    border-bottom: 2px solid transparent;
    transition: border-color var(--transition);
}
.nav-list a:hover {
    border-bottom-color: var(--accent);
    color: #fff;
}

.nav-cta {
    margin-left: 10px;
}

/* Гамбургер для мобильных */
.hamburger {
    display: none;
    flex-direction: column;
    justify-content: space-between;
    width: 24px;
    height: 20px;
    background: none;
    border: none;
    cursor: pointer;
}
.hamburger span {
    display: block;
    height: 2px;
    width: 100%;
    background: #fff;
    border-radius: 2px;
    transition: var(--transition);
}

/* Hero */
.hero {
    background: linear-gradient(135deg, #0d2b4e 0%, #1a4b6b 100%);
    color: #fff;
    padding: 100px 0;
    text-align: center;
}
.hero-title {
    font-size: 2.8rem;
    font-weight: 700;
    margin-bottom: 20px;
    line-height: 1.2;
}
.hero-description {
    font-size: 1.2rem;
    opacity: 0.9;
    margin-bottom: 40px;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

/* Преимущества */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.feature-card {
    background: var(--white);
    padding: 40px 30px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    text-align: center;
    transition: transform var(--transition);
}
.feature-card:hover {
    transform: translateY(-5px);
}

.feature-icon {
    font-size: 2.5rem;
    color: var(--accent);
    margin-bottom: 20px;
}

.feature-title {
    font-size: 1.3rem;
    margin-bottom: 15px;
    color: var(--dark-blue);
}

/* Секция последних статей */
.section-title {
    text-align: center;
    font-size: 2rem;
    margin-bottom: 40px;
    color: var(--dark-blue);
}

.articles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 25px;
}

.article-card {
    background: var(--light-bg);
    border-radius: var(--border-radius);
    padding: 25px;
    box-shadow: var(--shadow);
    transition: box-shadow var(--transition);
}
.article-card:hover {
    box-shadow: 0 6px 12px rgba(0,0,0,0.1);
}

.article-card.placeholder .article-content h3 {
    color: var(--dark-blue);
    margin-bottom: 10px;
}
.authors {
    font-style: italic;
    color: #666;
    margin-bottom: 10px;
}
.abstract {
    color: #555;
    margin-bottom: 15px;
}
.read-more {
    font-weight: 600;
    color: var(--accent);
}

/* CTA */
.cta {
    background: var(--light-bg);
}
.cta-title {
    font-size: 2rem;
    margin-bottom: 15px;
    color: var(--dark-blue);
}
.cta-text {
    margin-bottom: 30px;
    font-size: 1.1rem;
}

/* Футер */
.site-footer {
    background: var(--dark-blue);
    color: #ddd;
    padding-top: 60px;
}
.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 40px;
    padding-bottom: 40px;
    border-bottom: 1px solid rgba(255,255,255,0.1);
}
.footer-col h4 {
    color: #fff;
    margin-bottom: 20px;
    font-size: 1.1rem;
}
.footer-col p, .footer-col li {
    margin-bottom: 10px;
    font-size: 0.95rem;
}
.footer-col ul {
    list-style: none;
}
.footer-col a {
    color: #ccc;
}
.footer-col a:hover {
    color: #fff;
}
.footer-bottom {
    padding: 20px 0;
    font-size: 0.9rem;
}

/* Адаптивность */
@media (max-width: 768px) {
    .nav-list {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 70px;
        left: 0;
        right: 0;
        background: var(--dark-blue);
        padding: 20px;
        gap: 15px;
    }
    .nav-list.show {
        display: flex;
    }
    .hamburger {
        display: flex;
    }
    .nav-cta {
        display: none; /* на мобильном кнопка в меню не нужна, она есть в hero */
    }
    .hero-title {
        font-size: 2rem;
    }
    .hero-description {
        font-size: 1rem;
    }
    .section-padding {
        padding: 50px 0;
    }
}