:root {
    --bg: #f4f7fb;
    --surface: #ffffff;
    --surface-alt: #f8fbff;
    --ink: #10243b;
    --ink-muted: #30445d;
    --ink-soft: #5f7085;
    --line: #ccd7e3;
    --line-soft: #dde6ef;
    --accent: #0f6b73;
    --accent-soft: #d6ecee;
    --danger: #b23a3a;

    --font-sans: 'IBM Plex Sans', 'Segoe UI', sans-serif;
    --font-serif: 'Source Serif 4', Georgia, serif;

    --max-width: 1160px;
    --radius-lg: 18px;
    --radius-md: 12px;
    --radius-sm: 8px;

    --shadow-soft: 0 12px 40px rgba(16, 36, 59, 0.08);
    --shadow-card: 0 8px 22px rgba(16, 36, 59, 0.06);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    color: var(--ink);
    line-height: 1.6;
    background:
        radial-gradient(circle at 10% 10%, #eaf2fb 0%, transparent 42%),
        radial-gradient(circle at 90% 5%, #edf6f3 0%, transparent 38%),
        var(--bg);
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

a {
    color: inherit;
    text-decoration: none;
}

img,
svg {
    display: block;
    max-width: 100%;
}

[hidden] {
    display: none !important;
}

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

/* Navigation */
.site-nav {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(244, 247, 251, 0.86);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(204, 215, 227, 0.7);
}

.nav-shell {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 1.1rem 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1.5rem;
}

.brand {
    font-size: 1rem;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    font-weight: 600;
}

.nav-links {
    list-style: none;
    display: flex;
    align-items: center;
    gap: 1.2rem;
    flex-wrap: wrap;
    justify-content: flex-end;
}

.nav-links a {
    font-size: 0.86rem;
    color: var(--ink-soft);
    border-radius: 999px;
    padding: 0.45rem 0.9rem;
    border: 1px solid transparent;
    transition: all 0.2s ease;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--ink);
    background: var(--surface);
    border-color: var(--line);
}

/* Layout */
main {
    overflow: hidden;
}

.content-section {
    padding: 5.5rem 1.5rem;
}

.section-tone {
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.6), rgba(255, 255, 255, 0.88));
    border-top: 1px solid rgba(204, 215, 227, 0.45);
    border-bottom: 1px solid rgba(204, 215, 227, 0.45);
}

.section-shell {
    max-width: var(--max-width);
    margin: 0 auto;
}

.section-heading {
    display: grid;
    gap: 0.6rem;
    margin-bottom: 2rem;
}

.section-label {
    font-size: 0.78rem;
    text-transform: uppercase;
    letter-spacing: 0.14em;
    color: var(--ink-soft);
    font-weight: 600;
}

h1,
h2,
h3,
h4 {
    font-family: var(--font-serif);
    line-height: 1.22;
    color: var(--ink);
}

h1 {
    font-size: clamp(2.1rem, 5vw, 3.8rem);
    font-weight: 600;
    letter-spacing: -0.02em;
}

h2 {
    font-size: clamp(1.6rem, 3.5vw, 2.4rem);
    font-weight: 600;
    letter-spacing: -0.02em;
}

h3 {
    font-size: 1.34rem;
    font-weight: 600;
}

p {
    color: var(--ink-muted);
}

/* Hero */
.hero {
    padding: 4.5rem 1.5rem 5rem;
}

.hero-shell {
    max-width: var(--max-width);
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1.1fr 0.9fr;
    gap: 2.4rem;
    align-items: center;
}

.eyebrow {
    font-size: 0.82rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--ink-soft);
    margin-bottom: 1rem;
}

.hero-lead {
    margin-top: 1.2rem;
    font-size: 1.08rem;
    max-width: 62ch;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.7rem;
    margin-top: 1.8rem;
}

.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 999px;
    font-size: 0.9rem;
    font-weight: 600;
    padding: 0.64rem 1.2rem;
    border: 1px solid transparent;
    transition: all 0.2s ease;
}

.button-primary {
    background: var(--ink);
    color: #ffffff;
}

.button-primary:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-card);
}

.button-secondary {
    border-color: var(--line);
    background: var(--surface);
    color: var(--ink);
}

.button-secondary:hover {
    border-color: var(--ink-soft);
}

.hero-facts {
    margin-top: 1.4rem;
    list-style: none;
    display: grid;
    gap: 0.45rem;
}

.hero-facts li {
    font-size: 0.88rem;
    color: var(--ink-soft);
}

.hero-visual {
    display: grid;
    gap: 0.9rem;
}

.graph-card {
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-soft);
    padding: 1.1rem;
}

#nav-graph-container {
    width: 100%;
    max-width: 420px;
    margin: 0 auto;
}

.nav-graph-svg {
    width: 100%;
    height: auto;
}

.graph-caption {
    font-size: 0.84rem;
    color: var(--ink-soft);
}

.graph-placeholder {
    font-size: 0.84rem;
    color: var(--ink-soft);
}

/* Shared content blocks */
.two-column {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1.4rem;
}

.card-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1rem;
}

.feature-card,
.interest-card,
.course-card,
.resource-column,
.document-item,
.panel {
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-card);
}

.feature-card,
.interest-card,
.course-card,
.resource-column,
.document-item,
.panel {
    padding: 1.2rem;
}

.feature-card p,
.interest-card p,
.course-card p {
    margin-top: 0.65rem;
    font-size: 0.95rem;
}

.materials-strip {
    margin-top: 1.5rem;
    padding: 1.2rem;
    border: 1px dashed var(--line);
    border-radius: var(--radius-md);
    background: var(--surface-alt);
}

.materials-strip h3 {
    font-size: 1.06rem;
}

.materials-strip ul {
    margin-top: 0.7rem;
    list-style: none;
    display: grid;
    gap: 0.42rem;
}

.materials-strip a {
    color: var(--accent);
    font-weight: 500;
}

.materials-strip a:hover,
.text-link:hover,
.resource-column a:hover,
.document-action:hover {
    text-decoration: underline;
    text-decoration-thickness: 1px;
}

.interest-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 1rem;
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1rem;
}

.course-card header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    gap: 0.6rem;
    margin-bottom: 0.5rem;
}

.course-code {
    font-size: 0.78rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    font-weight: 600;
    color: var(--ink-soft);
}

.course-term {
    font-size: 0.78rem;
    color: var(--ink-soft);
}

.course-meta {
    margin-top: 0.8rem;
    font-size: 0.84rem;
    color: var(--ink-soft);
}

.text-link {
    margin-top: 0.9rem;
    display: inline-block;
    color: var(--accent);
    font-size: 0.9rem;
    font-weight: 500;
}

.resource-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1rem;
}

.resource-column h3 {
    font-size: 1.06rem;
    margin-bottom: 0.7rem;
}

.resource-column ul {
    list-style: none;
    display: grid;
    gap: 0.45rem;
}

.resource-column a {
    color: var(--ink-muted);
    font-size: 0.93rem;
}

/* Dossier */
.dossier-intro {
    max-width: 80ch;
    margin-bottom: 1.2rem;
}

.dossier-panel {
    background: rgba(255, 255, 255, 0.7);
    border: 1px solid var(--line);
    border-radius: var(--radius-lg);
    padding: 1.25rem;
}

.login-box {
    max-width: 560px;
    display: grid;
    gap: 0.8rem;
}

.login-title {
    color: var(--ink);
    font-weight: 600;
}

.login-box form {
    display: flex;
    gap: 0.6rem;
    align-items: center;
}

.login-box input {
    width: 100%;
    min-width: 220px;
    border: 1px solid var(--line);
    border-radius: var(--radius-sm);
    padding: 0.68rem 0.85rem;
    font-family: var(--font-sans);
    font-size: 0.92rem;
    color: var(--ink);
    background: var(--surface);
}

.login-box input:focus {
    outline: 2px solid rgba(15, 107, 115, 0.2);
    border-color: var(--accent);
}

.login-box button,
.logout-btn {
    border: 1px solid transparent;
    border-radius: var(--radius-sm);
    background: var(--ink);
    color: #ffffff;
    font-family: var(--font-sans);
    font-size: 0.88rem;
    font-weight: 600;
    padding: 0.66rem 1rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

.login-box button:hover,
.logout-btn:hover {
    transform: translateY(-1px);
}

.auth-message {
    min-height: 1.25rem;
    font-size: 0.85rem;
    color: var(--ink-soft);
}

.auth-message.error {
    color: var(--danger);
}

.auth-message.success {
    color: var(--accent);
}

.protected-content {
    display: grid;
    gap: 1rem;
}

.protected-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    gap: 1rem;
}

.protected-header h3 {
    font-size: 1.45rem;
}

.documents-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem;
}

.document-item {
    display: grid;
    gap: 0.55rem;
}

.document-item h4 {
    font-size: 1.04rem;
}

.document-item p {
    font-size: 0.89rem;
}

.document-action {
    width: fit-content;
    margin-top: 0.15rem;
    font-size: 0.86rem;
    font-weight: 600;
    color: var(--accent);
}

.document-item:not(.is-available) .document-action {
    color: var(--ink-soft);
    cursor: not-allowed;
    pointer-events: none;
}

.document-item.is-available {
    border-color: rgba(15, 107, 115, 0.45);
    background: linear-gradient(180deg, #ffffff, #f5fbfb);
}

/* Course page */
.course-page {
    padding: 4.5rem 1.5rem 5.5rem;
}

.course-shell {
    max-width: var(--max-width);
    margin: 0 auto;
    display: grid;
    gap: 1.8rem;
}

.breadcrumb {
    font-size: 0.86rem;
    color: var(--ink-soft);
}

.breadcrumb:hover {
    color: var(--ink);
}

.course-intro {
    display: grid;
    gap: 0.8rem;
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-soft);
    padding: 1.4rem;
}

.course-intro .section-label {
    margin: 0;
}

.course-intro p {
    max-width: 78ch;
}

.course-meta-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 0.8rem;
}

.panel h3 {
    font-size: 1.06rem;
}

.panel p,
.panel li {
    font-size: 0.92rem;
    color: var(--ink-muted);
}

.panel ul {
    margin-top: 0.7rem;
    list-style: none;
    display: grid;
    gap: 0.45rem;
}

.material-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem;
}

.material-card h3 {
    font-size: 1.08rem;
}

.material-list {
    margin-top: 0.75rem;
    list-style: none;
    display: grid;
    gap: 0.45rem;
}

.material-list a,
.material-note a {
    color: var(--accent);
    font-size: 0.9rem;
}

.material-note {
    margin-top: 0.75rem;
    font-size: 0.88rem;
    color: var(--ink-soft);
}

.placeholder-text {
    margin-top: 0.75rem;
    font-size: 0.88rem;
    color: var(--ink-soft);
    font-style: italic;
}

.core-materials {
    display: grid;
    gap: 1rem;
}

.weekly-materials {
    display: grid;
    gap: 1rem;
}

.weekly-heading {
    display: grid;
    gap: 0.45rem;
}

.week-list {
    display: grid;
    gap: 0.85rem;
}

.assignment-list {
    display: grid;
    gap: 0.85rem;
    margin-top: 0.75rem;
}

.week-item {
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-card);
    overflow: hidden;
}

.week-item summary {
    list-style: none;
    cursor: pointer;
    padding: 1rem 1.15rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
    border-bottom: 1px solid transparent;
}

.week-item summary::-webkit-details-marker {
    display: none;
}

.week-item[open] summary {
    border-bottom-color: var(--line-soft);
    background: #fbfdff;
}

.week-title {
    font-family: var(--font-serif);
    font-size: 1.08rem;
    color: var(--ink);
}

.week-status {
    flex-shrink: 0;
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    font-weight: 600;
    color: var(--accent);
    background: var(--accent-soft);
    border-radius: 999px;
    padding: 0.22rem 0.56rem;
}

.week-status-soon {
    color: var(--ink-soft);
    background: #e8eef6;
}

.week-content {
    padding: 1rem 1.15rem 1.2rem;
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.75rem;
}

.week-block {
    border: 1px solid var(--line-soft);
    border-radius: var(--radius-sm);
    padding: 0.85rem;
    background: #fcfeff;
}

.week-block h3 {
    font-size: 1rem;
}

.week-block .placeholder-text {
    margin-top: 0.5rem;
}

/* Footer */
.site-footer {
    border-top: 1px solid var(--line);
    background: rgba(255, 255, 255, 0.6);
}

.footer-shell {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 1.4rem 1.5rem 2rem;
}

.site-footer p {
    font-size: 0.8rem;
    color: var(--ink-soft);
}

/* Motion */
.reveal {
    opacity: 0;
    transform: translateY(16px);
    transition: opacity 0.5s ease, transform 0.5s ease;
}

.reveal.is-visible {
    opacity: 1;
    transform: translateY(0);
}

/* Responsive */
@media (max-width: 1024px) {
    .hero-shell {
        grid-template-columns: 1fr;
    }

    .card-grid,
    .interest-grid,
    .course-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .resource-grid,
    .course-meta-grid,
    .material-grid {
        grid-template-columns: 1fr;
    }

    .week-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 760px) {
    .nav-shell {
        flex-direction: column;
        align-items: flex-start;
    }

    .nav-links {
        gap: 0.45rem;
        width: 100%;
    }

    .hero,
    .content-section,
    .course-page {
        padding-left: 1rem;
        padding-right: 1rem;
    }

    .two-column,
    .card-grid,
    .interest-grid,
    .course-grid,
    .documents-grid {
        grid-template-columns: 1fr;
    }

    .login-box form {
        flex-direction: column;
        align-items: stretch;
    }
}

@media print {
    .site-nav,
    #dossier,
    .site-footer {
        display: none;
    }

    body {
        background: #ffffff;
    }

    .content-section,
    .hero,
    .course-page {
        padding: 1.5rem 0;
    }
}