/* Header CSS - Gia Sư Trí Đức */
:root {
    --primary: #1e3a8a;
    --primary-dark: #0f172a;
    --primary-light: #2563eb;
    --accent: #f59e0b;
    --accent-dark: #d97706;
    --accent-light: #fffbeb;
    --emerald: #059669;
    --dark: #1e293b;
    --gray: #64748b;
    --light: #f8fafc;
    --white: #ffffff;
    --border: #e2e8f0;
    --radius: 14px;
    --radius-btn: 10px;
    --font-heading: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-main: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, sans-serif;
    --shadow: 0 10px 30px rgba(30, 58, 138, 0.08);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.section-container {
    max-width: 1240px;
    margin: 0 auto;
    padding: 0 24px;
    width: 100%;
}
@media (max-width: 768px) {
    .section-container {
        padding: 0 16px;
    }
}

/* Top Bar */
.top-bar {
    background: #0f172a;
    color: #e2e8f0;
    font-size: 13px;
    padding: 8px 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}
.top-bar .section-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.top-bar-left {
    display: flex;
    align-items: center;
    gap: 15px;
}
.top-bar-left i {
    color: var(--accent);
}
.badge-portal {
    background: rgba(245, 158, 11, 0.2);
    color: #fbbf24;
    padding: 2px 10px;
    border-radius: 4px;
    font-size: 11px;
    font-weight: 700;
}
.top-bar-right {
    display: flex;
    align-items: center;
    gap: 20px;
}
.top-bar-right a {
    color: #e2e8f0;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    transition: var(--transition);
}
.top-bar-right a:hover {
    color: var(--accent);
}

/* Main Site Header */
.site-header {
    background: var(--white);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
    transition: var(--transition);
}
.site-header.scrolled {
    box-shadow: 0 8px 30px rgba(30, 58, 138, 0.12);
}
.header-container {
    max-width: 1240px;
    margin: 0 auto;
    padding: 14px 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
}
.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
    flex-shrink: 0;
}
.logo-mark {
    width: 44px;
    height: 44px;
    background: linear-gradient(135deg, #1e3a8a 0%, #2563eb 100%);
    color: #ffffff;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 22px;
    box-shadow: 0 4px 14px rgba(37, 99, 235, 0.3);
}
.logo-text {
    display: flex;
    flex-direction: column;
}
.brand-title {
    font-family: var(--font-heading);
    font-size: 22px;
    font-weight: 800;
    color: var(--primary);
    line-height: 1.1;
    letter-spacing: -0.5px;
}
.brand-title .accent-text {
    color: var(--accent);
}
.brand-sub {
    font-size: 11px;
    font-weight: 700;
    color: var(--gray);
    letter-spacing: 0.5px;
    text-transform: uppercase;
}

/* Nav Menu */
.nav-menu {
    display: flex;
    align-items: center;
}
.nav-list {
    display: flex;
    align-items: center;
    list-style: none;
    margin: 0;
    padding: 0;
    gap: 24px;
    white-space: nowrap;
}
.nav-item {
    position: relative;
}
.nav-link {
    display: block;
    padding: 8px 0;
    font-size: 15px;
    font-weight: 600;
    color: var(--dark);
    text-decoration: none;
    transition: var(--transition);
    position: relative;
}
.nav-link:hover, .nav-link.active {
    color: var(--primary-light);
}
.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2.5px;
    background: var(--accent);
    border-radius: 2px;
    transition: var(--transition);
}
.nav-link:hover::after, .nav-link.active::after {
    width: 100%;
}
.nav-item.mobile-only {
    display: none;
}

/* Header Actions */
.header-actions {
    display: flex;
    align-items: center;
    gap: 15px;
    flex-shrink: 0;
}
.header-cta-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
    color: #ffffff;
    font-size: 14px;
    font-weight: 700;
    padding: 10px 20px;
    border-radius: var(--radius-btn);
    text-decoration: none;
    box-shadow: 0 4px 14px rgba(245, 158, 11, 0.35);
    transition: var(--transition);
    white-space: nowrap;
}
.header-cta-btn:hover {
    background: linear-gradient(135deg, #d97706 0%, #b45309 100%);
    color: #ffffff;
    transform: translateY(-2px);
    box-shadow: 0 6px 18px rgba(245, 158, 11, 0.45);
}

/* Mobile Toggle */
.mobile-toggle {
    display: none;
    background: transparent;
    border: none;
    font-size: 24px;
    color: var(--primary);
    cursor: pointer;
    padding: 4px;
    align-items: center;
    justify-content: center;
}

/* Responsive */
@media (max-width: 1100px) {
    .nav-list {
        gap: 16px;
    }
    .nav-link {
        font-size: 14px;
    }
}
@media (max-width: 992px) {
    .top-bar { display: none; }
    .header-actions { display: none; }
    .mobile-toggle { display: flex; }
    
    .nav-menu {
        position: fixed;
        top: 72px;
        left: 0;
        right: 0;
        bottom: 0;
        background: #ffffff;
        flex-direction: column;
        align-items: flex-start;
        padding: 24px;
        overflow-y: auto;
        transform: translateX(-100%);
        transition: transform 0.3s ease;
        box-shadow: 0 20px 40px rgba(0,0,0,0.1);
    }
    .nav-menu.active {
        transform: translateX(0);
    }
    .nav-list {
        flex-direction: column;
        align-items: flex-start;
        width: 100%;
        gap: 0;
    }
    .nav-item {
        width: 100%;
        border-bottom: 1px solid var(--border);
    }
    .nav-link {
        padding: 14px 0;
        font-size: 16px;
    }
    .nav-item.mobile-only {
        display: block;
    }
    .nav-item.mobile-only .nav-link {
        color: var(--accent-dark);
        font-weight: 700;
    }
}