.main-header {
    background-color: rgba(1, 4, 9, 0.8);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(10px);
}
.main-header .container { display: flex; justify-content: space-between; align-items: center; padding-top:0; padding-bottom:0; }
.logo { font-family: var(--font-family-title); font-size: 1.8rem; font-weight: bold; color: white; letter-spacing: 2px; }
.nav-links { list-style: none; display: flex; gap: 1.5rem; }
.nav-links a { color: var(--text-primary); font-weight: bold; position: relative; padding: 5px 0; text-transform: uppercase; font-size: 0.9rem; }
.nav-links a::after { content: ''; position: absolute; bottom: 0; left: 0; width: 0; height: 2px; background-color: var(--accent-blue); transition: width 0.3s ease; }
.nav-links a:hover::after, .nav-links a.active::after { width: 100%; }