:root {
    --primary: #005D8A;
    --primary-dark: #00456B;
    --secondary: #FFC107;
    --secondary-dark: #E6AD00;
    --light: #F8F9FA;
    --dark: #212529;
    --gray: #6C757D;
    --light-gray: #E9ECEF;
    --white: #FFFFFF;
    --success: #28A745;
    --warning: #FFC107;
    --danger: #DC3545;
    --info: #17A2B8;
    --blue-accent: #0074D9;
}

body {
    font-family: 'Source Sans 3', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: var(--dark);
    background-color: var(--light);
    line-height: 1.7;
}

/* Modern Header */
.site-header {
    background-color: var(--white);
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 1030;
}

.site-header .navbar-brand {
    font-weight: 700;
    color: var(--primary);
}

.site-header .nav-link {
    color: var(--dark);
    font-weight: 500;
    padding: 0.5rem 1rem;
    margin: 0 0.25rem;
    border-radius: 4px;
    transition: all 0.2s ease;
}

.site-header .nav-link:hover {
    background-color: var(--light-gray);
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, rgba(0,93,138,0.88) 0%, rgba(29,53,87,0.88) 100%);
    color: var(--white);
    padding: 4rem 0;
    margin-bottom: 0;
    position: relative;
}

.hero-content {
    max-width: 800px;
}

.hero h1 {
    font-family: 'Merriweather', Georgia, serif;
    font-weight: 800;
    font-size: 2.4rem;
    margin-bottom: 1rem;
    line-height: 1.3;
}

.hero p.lead {
    font-size: 1.15rem;
    margin-bottom: 0;
    opacity: 0.92;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    background: rgba(255,255,255,0.15);
    padding: 0.35rem 0.9rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

/* Breadcrumb */
.breadcrumb-nav {
    padding: 0.75rem 0;
    font-size: 0.9rem;
    background-color: var(--white);
    border-bottom: 1px solid var(--light-gray);
}

.breadcrumb-nav .breadcrumb {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    padding: 0;
    margin: 0;
    gap: 0.25rem;
}

.breadcrumb-nav .breadcrumb li:not(:last-child)::after {
    content: ">";
    margin-left: 0.4rem;
    color: var(--gray);
}

.breadcrumb-nav a {
    color: var(--primary);
    text-decoration: none;
}

.breadcrumb-nav a:hover {
    text-decoration: underline;
}

/* TOC */
.toc-container {
    background-color: var(--white);
    border: 1px solid var(--light-gray);
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 2rem;
}

.toc-container h2 {
    font-size: 1.2rem;
    color: var(--primary);
    margin-bottom: 1rem;
    font-weight: 700;
}

.toc-container ol {
    margin: 0;
    padding-left: 1.25rem;
}

.toc-container li {
    margin-bottom: 0.4rem;
}

.toc-container a {
    color: var(--dark);
    text-decoration: none;
    transition: color 0.2s;
}

.toc-container a:hover {
    color: var(--primary);
}

/* Content Sections */
.content-section {
    background-color: var(--white);
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    padding: 2rem;
    margin-bottom: 2rem;
}

.content-section h2 {
    font-family: 'Merriweather', Georgia, serif;
    color: var(--primary);
    margin-bottom: 1.5rem;
    font-weight: 700;
    font-size: 1.6rem;
}

.content-section h3 {
    color: var(--primary-dark);
    margin-top: 1.5rem;
    margin-bottom: 1rem;
    font-weight: 600;
    font-size: 1.2rem;
}

/* Alert Cards */
.alert-card {
    border-radius: 8px;
    border-left: 4px solid;
    padding: 1.25rem;
    margin-bottom: 1.5rem;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.alert-card.info { border-color: var(--info); background-color: rgba(23, 162, 184, 0.1); }
.alert-card.warning { border-color: var(--warning); background-color: rgba(255, 193, 7, 0.1); }
.alert-card.danger { border-color: var(--danger); background-color: rgba(220, 53, 69, 0.1); }
.alert-card.success { border-color: var(--success); background-color: rgba(40, 167, 69, 0.1); }

.alert-card-title {
    display: flex;
    align-items: center;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.alert-card-title svg {
    margin-right: 0.5rem;
}

/* Fuel Chain Cards */
.chain-card {
    background-color: var(--white);
    border-radius: 8px;
    box-shadow: 0 3px 12px rgba(0,0,0,0.06);
    padding: 1.25rem;
    margin-bottom: 1rem;
    border: 1px solid var(--light-gray);
    transition: transform 0.2s ease;
}

.chain-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
}

.chain-card h4 {
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--primary);
    margin-bottom: 0.4rem;
}

.chain-card .chain-type {
    font-size: 0.85rem;
    color: var(--gray);
    font-weight: 500;
}

/* Price Comparison Table */
.price-table {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0;
    margin-bottom: 1.5rem;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 2px 10px rgba(0,0,0,0.06);
}

.price-table thead th {
    background-color: var(--primary);
    color: var(--white);
    padding: 0.9rem 1rem;
    font-weight: 600;
    text-align: left;
}

.price-table tbody td {
    padding: 0.8rem 1rem;
    border-bottom: 1px solid var(--light-gray);
}

.price-table tbody tr:last-child td {
    border-bottom: none;
}

.price-table tbody tr:nth-child(even) {
    background-color: rgba(0,93,138,0.03);
}

.price-higher {
    color: var(--danger);
    font-weight: 600;
}

.price-lower {
    color: var(--success);
    font-weight: 600;
}

/* Tip Box */
.tip-box {
    background: linear-gradient(135deg, rgba(0,93,138,0.06) 0%, rgba(0,93,138,0.02) 100%);
    border: 1px solid rgba(0,93,138,0.15);
    border-radius: 8px;
    padding: 1.25rem;
    margin: 1.5rem 0;
}

.tip-box strong {
    color: var(--primary);
}

/* FAQ Section */
.faq-section {
    background-color: var(--white);
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    padding: 2rem;
    margin-bottom: 2rem;
}

.faq-item {
    border-bottom: 1px solid var(--light-gray);
    padding: 0;
    margin-bottom: 0;
}

.faq-item:last-child {
    border-bottom: none;
}

.faq-question {
    width: 100%;
    text-align: left;
    background: none;
    border: none;
    padding: 1.1rem 2rem 1.1rem 0;
    font-weight: 600;
    font-size: 1rem;
    color: var(--dark);
    cursor: pointer;
    position: relative;
    transition: color 0.2s;
}

.faq-question:hover {
    color: var(--primary);
}

.faq-question::after {
    content: "+";
    position: absolute;
    right: 0;
    top: 50%;
    transform: translateY(-50%);
    font-size: 1.4rem;
    font-weight: 300;
    color: var(--primary);
    transition: transform 0.2s;
}

.faq-question[aria-expanded="true"]::after {
    content: "-";
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease, padding 0.35s ease;
    padding: 0 0;
}

.faq-answer.show {
    max-height: 500px;
    padding: 0 0 1.1rem 0;
}

/* Map */
#map {
    height: 400px;
    border-radius: 8px;
    margin-top: 1rem;
    z-index: 1;
    border: 1px solid var(--light-gray);
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    background-color: var(--primary);
    color: var(--white);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    text-decoration: none;
    opacity: 0;
    transition: opacity 0.3s ease, transform 0.3s ease;
    z-index: 1000;
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
    border: none;
}

.back-to-top.show { opacity: 1; }
.back-to-top:hover { transform: translateY(-5px); color: var(--white); }

/* Footer */
.site-footer {
    background-color: var(--primary);
    color: var(--white);
    padding: 4rem 0 2rem;
    margin-top: 3rem;
}

.site-footer a {
    color: rgba(255,255,255,0.8);
    text-decoration: none;
    transition: color 0.2s ease;
}

.site-footer a:hover {
    color: var(--white);
    text-decoration: underline;
}

.footer-links {
    list-style: none;
    padding: 0;
    margin: 0;
}

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

.site-footer h5 {
    font-weight: 700;
    margin-bottom: 1.5rem;
}

.footer-bottom {
    border-top: 1px solid rgba(255,255,255,0.1);
    padding-top: 2rem;
    margin-top: 2rem;
    font-size: 0.9rem;
}

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

:focus {
    outline: 3px solid rgba(0,93,138,0.5);
    outline-offset: 2px;
}

/* Responsive */
@media (max-width: 992px) {
    .hero h1 { font-size: 2rem; }
    .content-section { padding: 1.5rem; }
}

@media (max-width: 768px) {
    .hero { padding: 3rem 0; }
    .hero h1 { font-size: 1.8rem; }
    #map { height: 300px; }
    .price-table-wrap { border-radius: 8px; overflow-x: auto; -webkit-overflow-scrolling: touch; }
    .price-table th, .price-table td { white-space: nowrap; }
}

@media (max-width: 576px) {
    .hero { padding: 2rem 0; }
    .hero h1 { font-size: 1.5rem; }
    .content-section { padding: 1.25rem; }
    .back-to-top { bottom: 1.5rem; right: 1rem; width: 2.5rem; height: 2.5rem; }
}