/* ECON 510 site theme — UNC Tar Heels (Navy / Carolina Blue) */

:root {
    --navy: #13294B;
    --navy-band: #1E3A63;
    --carolina: #4B9CD3;
    --carolina-light: #a9d4ec;
    --carolina-pale: #eaf4fb;
    --paper: #ffffff;
    --page-bg: #eef2f6;
    --ink: #1f2937;
    --ink-soft: #4b5563;
    --line: #d7e0ea;
    --line-soft: #e8edf3;
    --amber-highlight: #fef3c7;
    --amber-highlight-border: #f6d38a;
    --alert: #c0392b;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.65;
    background-color: var(--page-bg);
    color: var(--ink);
    padding: 32px 20px;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    background: var(--paper);
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 4px 24px rgba(19, 41, 75, 0.10), 0 1px 3px rgba(19, 41, 75, 0.08);
}

/* Masthead — navy header band bled to the card's edges */
.masthead {
    background: var(--navy-band);
    margin: -30px -30px 24px -30px;
    padding: 26px 30px 20px;
    border-radius: 10px 10px 0 0;
    border-bottom: 3px solid var(--carolina);
}

.masthead h1 {
    font-family: 'Source Serif 4', Georgia, serif;
    color: #ffffff;
    font-size: 1.55rem;
    font-weight: 600;
    letter-spacing: 0.01em;
    margin-bottom: 0.4rem;
}

.masthead .subtitle {
    color: var(--carolina-light);
    font-family: 'Inter', sans-serif;
    font-size: 1.05rem;
    font-weight: 500;
    margin-bottom: 0;
}

.masthead .btn-outline-light {
    border-color: rgba(255, 255, 255, 0.55);
    color: #ffffff;
}

.masthead .btn-outline-light:hover {
    background-color: var(--carolina);
    border-color: var(--carolina);
    color: #ffffff;
}

/* Fallback: h1/subtitle used outside a .masthead wrapper */
h1 {
    color: var(--navy);
    font-family: 'Source Serif 4', Georgia, serif;
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.subtitle {
    color: var(--carolina);
    font-size: 1.25rem;
    margin-bottom: 2rem;
}

/* Back-to-home link — sits between the masthead and the instructor card */
.back-link {
    display: inline-block;
    font-family: 'Inter', sans-serif;
    text-transform: uppercase;
    letter-spacing: 0.12em;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--carolina);
    text-decoration: none;
}

.back-link:hover {
    color: var(--navy);
}

.instructor-info {
    background-color: var(--carolina-pale);
    padding: 20px;
    border-radius: 6px;
    margin-bottom: 30px;
    border-left: 4px solid var(--carolina);
}

.instructor-info p {
    margin-bottom: 0.5rem;
}

/* Accordion */
.accordion {
    border: 1px solid var(--line);
    border-radius: 8px;
    overflow: hidden;
    margin-bottom: 20px;
}

.accordion-item {
    border-bottom: 1px solid var(--line);
    background: var(--paper);
}

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

.accordion-button {
    background-color: var(--carolina-pale);
    color: var(--navy);
    font-family: 'Inter', sans-serif;
    font-weight: 600;
    font-size: 1.15rem;
    letter-spacing: 0.01em;
    padding: 1rem 1.25rem;
    border: none;
}

.accordion-button:not(.collapsed) {
    background-color: var(--carolina);
    color: #ffffff;
    box-shadow: none;
}

.accordion-button:focus {
    box-shadow: 0 0 0 3px rgba(75, 156, 211, 0.25);
    border-color: var(--carolina);
}

.accordion-button::after {
    filter: brightness(0.35);
}

.accordion-button:not(.collapsed)::after {
    filter: brightness(0) invert(1);
}

.accordion-body {
    padding: 1.25rem;
    background-color: var(--paper);
    border-top: 1px solid var(--line);
}

.accordion-body p:last-child,
.accordion-body ul:last-child,
.accordion-body ol:last-child {
    margin-bottom: 0;
}

/* Nested collapsible sections */
.nested-collapse {
    margin: 15px 0;
}

.nested-header {
    background-color: var(--line-soft);
    padding: 0.75rem 1rem;
    border: 1px solid var(--line);
    border-radius: 4px;
    cursor: pointer;
    font-weight: 500;
    color: var(--navy);
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: background-color 0.15s ease;
}

.nested-header:hover {
    background-color: var(--carolina-pale);
}

.nested-header.active {
    background-color: var(--navy);
    color: #ffffff;
    border-color: var(--navy);
}

.nested-header::after {
    content: "▼";
    font-size: 0.8rem;
    transition: transform 0.2s ease;
}

.nested-header.active::after {
    transform: rotate(-180deg);
}

.nested-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease;
}

.nested-content.show {
    max-height: 2000px;
    margin-top: 10px;
}

/* Tables */
table {
    width: 100%;
    border-collapse: collapse;
    margin: 15px 0;
}

table th {
    background-color: var(--navy);
    color: #ffffff;
    padding: 12px;
    text-align: left;
    font-weight: 600;
}

table td {
    padding: 10px 12px;
    border-bottom: 1px solid var(--line);
}

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

table tr:nth-child(even) {
    background-color: var(--line-soft);
}

.schedule-table {
    font-size: 0.95rem;
}

.schedule-table td {
    padding: 8px;
    vertical-align: top;
}

.schedule-table .week-col {
    font-weight: 600;
    background-color: var(--carolina-pale);
}

/* Links */
a {
    color: var(--carolina);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
    color: var(--navy);
}

/* Lists */
ul, ol {
    margin: 10px 0;
    padding-left: 25px;
}

li {
    margin-bottom: 8px;
}

.highlight {
    background-color: var(--amber-highlight);
    border: 1px solid var(--amber-highlight-border);
    padding: 2px 6px;
    border-radius: 3px;
}

.text-red {
    color: var(--alert);
    font-weight: bold;
}

.emphasis {
    color: var(--alert);
    font-weight: 600;
}

h5 {
    color: var(--navy);
    font-family: 'Source Serif 4', Georgia, serif;
    font-weight: 600;
    margin-top: 1.5rem;
    margin-bottom: 1rem;
}

h6 {
    color: var(--navy);
    font-family: 'Source Serif 4', Georgia, serif;
    font-weight: 600;
    margin-top: 1rem;
}

blockquote {
    background-color: var(--carolina-pale);
    padding: 15px 20px;
    border-left: 4px solid var(--carolina);
    margin: 15px 0;
    font-family: 'Source Serif 4', Georgia, serif;
    font-style: italic;
    color: var(--ink-soft);
}

footer {
    margin-top: 10px;
    padding-top: 10px;
    border-top: 1px solid var(--line);
    text-align: center;
    color: var(--ink-soft);
    font-size: 0.9rem;
}