/* ==========================================================================
   CDSS 94 - Building Thoughtful AI Systems
   Course Website Styles
   ========================================================================== */

/* ==========================================================================
   1. CSS Variables & Theme
   ========================================================================== */
:root {
    /* Colors */
    --bg: #dcd0c024;
    --bg-card: #dcd0c024;
    --text-primary: #1a1a1a;
    --text-secondary: #555;
    --text-muted: #888;
    --border-color: #999;
    --accent: #1a1a1a;
    
    /* Tag Colors - Warm Beige */
    --tag-due-bg: #fef7ed;
    --tag-due-text: #9a6b3a;
    --tag-release-bg: #f0fdf4;
    --tag-release-text: #5c8a6b;
    
    /* Calendar Colors - Warm */
    --calendar-border: #e5ddd5;
    --calendar-header-bg: #faf8f5;
    --calendar-row-bg: #fffefb;
    --calendar-row-hover: #fdf9f3;
    --calendar-cell-border: #ebe5dc;
    --calendar-text: #3d3529;
    --calendar-text-muted: #8b8075;
    
    /* Typography */
    --serif: 'Newsreader', Georgia, serif;
    --sans: 'Source Sans 3', -apple-system, sans-serif;
}

/* ==========================================================================
   2. Base Styles & Reset
   ========================================================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--sans);
    background: var(--bg);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

/* ==========================================================================
   3. Layout
   ========================================================================== */
.container {
    display: grid;
    grid-template-columns: 420px 1fr;
    min-height: 100vh;
    max-width: 1600px;
    margin: 0;
    padding: 100px 60px 100px 80px;
    gap: 120px;
}

/* ==========================================================================
   4. Sidebar
   ========================================================================== */
.sidebar {
    position: sticky;
    top: 60px;
    height: fit-content;
}

.site-title {
    font-family: var(--serif);
    font-size: 76px;
    font-weight: 400;
    line-height: 1.15;
    letter-spacing: -0.02em;
    margin-bottom: 24px;
}

.site-description {
    font-size: 17px;
    line-height: 1.8;
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.site-description a {
    color: var(--text-primary);
    text-decoration: underline;
    text-underline-offset: 2px;
}

.site-meta {
    font-size: 14px;
    color: var(--text-muted);
    margin-bottom: 40px;
}

.subscribe-btn {
    display: inline-flex;
    align-items: center;
    padding: 12px 28px;
    background: var(--text-primary);
    color: white;
    border: none;
    border-radius: 6px;
    font-family: var(--sans);
    font-size: 15px;
    font-weight: 500;
    cursor: pointer;
    transition: opacity 0.2s;
}

.subscribe-btn:hover {
    opacity: 0.85;
}

.sidebar-footer {
    position: absolute;
    bottom: 0;
    left: 0;
    display: flex;
    align-items: center;
    gap: 16px;
}

.social-links {
    display: flex;
    gap: 12px;
}

.social-links a {
    color: var(--text-primary);
    opacity: 0.6;
    transition: opacity 0.2s;
}

.social-links a:hover {
    opacity: 1;
}

.social-links svg {
    width: 18px;
    height: 18px;
}

.copyright {
    font-size: 13px;
    color: var(--text-muted);
}

/* ==========================================================================
   5. Teaching Staff
   ========================================================================== */
.teaching-staff {
    margin-top: 40px;
}

.staff-label {
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    margin-bottom: 16px;
}

.staff-grid {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
}

.staff-member {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    text-decoration: none;
    color: inherit;
}

a.staff-member:hover .staff-name {
    text-decoration: underline;
    text-underline-offset: 2px;
}

.staff-avatar {
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: #ccc;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    color: #888;
    overflow: hidden;
}

.staff-avatar img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.staff-name {
    font-size: 13px;
    font-weight: 500;
    color: var(--text-primary);
    text-align: center;
}

.staff-role {
    font-size: 11px;
    color: var(--text-muted);
    text-align: center;
    margin-top: -4px;
}

/* ==========================================================================
   6. Main Content
   ========================================================================== */
.main-content {
    padding-top: 20px;
}

/* ==========================================================================
   7. Navigation Pills
   ========================================================================== */
.nav-pills {
    display: flex;
    gap: 8px;
    margin-bottom: 32px;
}

.nav-pill {
    padding: 8px 16px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-secondary);
    background: transparent;
    border: 1px solid #ccc;
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.2s;
}

.nav-pill:hover {
    border-color: var(--text-primary);
    color: var(--text-primary);
}

.nav-pill.active {
    background: var(--text-primary);
    color: white;
    border-color: var(--text-primary);
}

/* ==========================================================================
   8. Section Headers
   ========================================================================== */
.section-header {
    font-family: var(--serif);
    font-size: 36px;
    font-weight: 400;
    margin: 48px 0 24px;
    padding-bottom: 12px;
    border-bottom: 1px solid #ccc;
}

.section-header:first-of-type {
    margin-top: 0;
}

.section-header.upcoming {
    opacity: 0.4;
}

/* ==========================================================================
   9. Featured Card
   ========================================================================== */
.featured-card {
    position: relative;
    padding: 20px 28px;
    margin-bottom: 24px;
    background: var(--bg-card);
    cursor: pointer;
    transition: background 0.2s;
}

.featured-card::before {
    content: '';
    position: absolute;
    inset: 0;
    border: 1px dashed var(--border-color);
    pointer-events: none;
}

.featured-card::after {
    content: '×';
    position: absolute;
    font-size: 14px;
    color: var(--border-color);
}

.featured-card .corner-tl,
.featured-card .corner-tr,
.featured-card .corner-bl,
.featured-card .corner-br {
    position: absolute;
    font-size: 12px;
    color: var(--border-color);
    line-height: 1;
}

.featured-card .corner-tl { top: -6px; left: -4px; }
.featured-card .corner-tr { top: -6px; right: -4px; }
.featured-card .corner-bl { bottom: -6px; left: -4px; }
.featured-card .corner-br { bottom: -6px; right: -4px; }

.featured-card:hover {
    background: #e0e0e0;
}

.featured-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.featured-content {
    display: flex;
    align-items: center;
    gap: 24px;
}

.featured-title {
    font-family: var(--sans);
    font-size: 15px;
    font-weight: 600;
    letter-spacing: -0.01em;
}

.featured-desc {
    font-size: 14px;
    color: var(--text-secondary);
}

.arrow-icon {
    color: var(--text-primary);
    flex-shrink: 0;
}

.arrow-icon svg {
    width: 20px;
    height: 20px;
}

/* ==========================================================================
   10. Post Cards (Syllabus)
   ========================================================================== */
.posts-list {
    display: flex;
    flex-direction: column;
}

.post-card {
    display: grid;
    grid-template-columns: 64px 280px 1fr 32px;
    align-items: center;
    gap: 24px;
    padding: 28px 0;
    border-top: 1px solid #ccc;
    cursor: pointer;
    transition: background 0.2s;
}

.post-card:hover {
    background: rgba(0,0,0,0.02);
    margin: 0 -20px;
    padding-left: 20px;
    padding-right: 20px;
}

.post-card:last-child {
    border-bottom: 1px solid #ccc;
}

.post-card.upcoming {
    opacity: 0.4;
    pointer-events: none;
    cursor: default;
}

.post-icon {
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.post-icon svg {
    width: 48px;
    height: 48px;
    stroke: var(--text-primary);
    stroke-width: 1;
    fill: none;
}

.post-title-group {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.post-title {
    font-family: var(--serif);
    font-size: 26px;
    font-weight: 400;
    line-height: 1.2;
    letter-spacing: -0.01em;
}

.post-date {
    font-size: 14px;
    color: var(--text-muted);
}

.post-description {
    font-size: 15px;
    line-height: 1.6;
    color: var(--text-secondary);
}

.post-arrow {
    justify-self: end;
    cursor: pointer;
    transition: transform 0.2s ease;
}

.post-card.expanded .post-arrow {
    transform: rotate(180deg);
}

.post-arrow svg {
    width: 20px;
    height: 20px;
    color: var(--text-primary);
}

/* Materials expandable section */
.post-materials {
    grid-column: 1 / -1;
    display: none;
    gap: 12px;
    padding: 8px 0 0 88px;
}

.post-card.expanded .post-materials {
    display: flex;
    flex-wrap: wrap;
}

.post-card.expanded {
    padding-bottom: 20px;
}

.material-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-primary);
    text-decoration: none;
    padding: 6px 14px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    transition: background 0.15s ease;
}

.material-link:hover {
    background: rgba(0,0,0,0.05);
}

.material-link svg {
    width: 16px;
    height: 16px;
}

.material-link.disabled {
    opacity: 0.35;
    pointer-events: none;
    cursor: default;
    border-style: dashed;
}

.material-credit {
    width: 100%;
    font-size: 11px;
    color: var(--text-muted);
    font-style: italic;
    margin-top: 4px;
}

/* Calendar material links */
.calendar-material-link {
    display: inline-block;
    font-size: 13px;
    font-weight: 500;
    color: var(--calendar-text);
    text-decoration: underline;
    text-underline-offset: 2px;
    margin-right: 12px;
}

.calendar-material-link:hover {
    color: var(--text-primary);
}

/* ==========================================================================
   11. Tags
   ========================================================================== */
.post-tag {
    display: inline-block;
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 4px 8px;
    border-radius: 4px;
    margin-top: 8px;
}

.tag-due {
    background: var(--tag-due-bg);
    color: var(--tag-due-text);
}

.tag-release {
    background: var(--tag-release-bg);
    color: var(--tag-release-text);
}

/* ==========================================================================
   12. Section Visibility
   ========================================================================== */
.projects-section {
    display: none;
}

.projects-section.active {
    display: block;
}

.schedule-section {
    display: block;
}

.schedule-section.hidden {
    display: none;
}

.calendar-section {
    display: none;
}

.calendar-section.active {
    display: block;
}

.policies-section {
    display: none;
}

.policies-section.active {
    display: block;
}

.policy-card {
    background: white;
    border-radius: 12px;
    padding: 32px;
    margin-bottom: 24px;
    border: 1px solid #ddd;
}

.policy-card .section-header {
    margin-top: 0;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.policies-content {
    font-size: 16px;
    line-height: 1.8;
    color: var(--text-secondary);
    max-width: 720px;
}

.policies-content p {
    margin-bottom: 12px;
}

.policies-heading {
    font-family: var(--sans);
    font-size: 17px;
    font-weight: 600;
    color: var(--text-primary);
    margin-top: 28px;
    margin-bottom: 8px;
    padding-top: 24px;
    border-top: 1px solid #e5e5e5;
}

.policies-heading:first-child {
    border-top: none;
    padding-top: 0;
    margin-top: 0;
}

.policies-content ul {
    margin: 8px 0 16px 20px;
}

.policies-content li {
    margin-bottom: 6px;
}

.policies-nav-list {
    list-style: none;
    margin-left: 0 !important;
}

.grade-breakdown {
    margin: 16px 0 24px;
}

.grade-item {
    display: flex;
    align-items: baseline;
    gap: 16px;
    padding: 12px 0;
    border-bottom: 1px solid #e5e5e5;
}

.grade-percent {
    font-family: var(--serif);
    font-size: 28px;
    font-weight: 500;
    color: var(--text-primary);
    min-width: 64px;
}

.grade-label {
    font-size: 16px;
    font-weight: 500;
    color: var(--text-primary);
}

.grade-detail {
    font-weight: 400;
    color: var(--text-muted);
    font-size: 14px;
}

/* ==========================================================================
   13. Calendar
   ========================================================================== */
.calendar-grid {
    display: grid;
    gap: 1px;
    background: var(--calendar-border);
    border: 1px solid var(--calendar-border);
    border-radius: 12px;
    overflow: hidden;
}

.calendar-header {
    display: grid;
    grid-template-columns: 80px 1.2fr 1fr 0.8fr 0.8fr;
    background: var(--calendar-header-bg);
}

.calendar-header-cell {
    padding: 14px 16px;
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--calendar-text-muted);
    background: var(--calendar-header-bg);
}

.calendar-row {
    display: grid;
    grid-template-columns: 80px 1.2fr 1fr 0.8fr 0.8fr;
    background: var(--calendar-row-bg);
}

.calendar-row:hover {
    background: var(--calendar-row-hover);
}

.calendar-row.break {
    opacity: 0.6;
    background: #faf6f0;
}

.calendar-row.highlight {
    background: linear-gradient(135deg, #fef7ed 0%, #fdf2e3 100%);
}

.calendar-cell {
    padding: 16px;
    border-left: 1px solid var(--calendar-cell-border);
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.calendar-cell:first-child {
    border-left: none;
    justify-content: center;
    align-items: center;
}

.date-display {
    text-align: center;
}

.date-month {
    font-size: 10px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--calendar-text-muted);
}

.date-day {
    font-size: 24px;
    font-weight: 400;
    color: var(--calendar-text);
}

.cell-label {
    font-size: 10px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--calendar-text-muted);
    margin-bottom: 2px;
}

.cell-content {
    font-size: 14px;
    font-weight: 500;
    color: var(--calendar-text);
}

.cell-subcontent {
    font-size: 13px;
    color: var(--calendar-text-muted);
}

.cell-banner {
    display: block;
    margin-top: 6px;
    padding: 3px 6px;
    background: var(--tag-due-bg);
    color: var(--tag-due-text);
    font-size: 10px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    border-radius: 3px;
    text-align: center;
}

.calendar-tag {
    display: inline-block;
    font-size: 10px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    padding: 3px 6px;
    border-radius: 3px;
    margin-top: 6px;
}

.calendar-tag.due {
    background: var(--tag-due-bg);
    color: var(--tag-due-text);
}

a.calendar-tag.due {
    text-decoration: underline;
    text-underline-offset: 2px;
}

a.calendar-tag.due:hover {
    opacity: 0.8;
}

.calendar-tag.release {
    background: var(--tag-release-bg);
    color: var(--tag-release-text);
}

/* ==========================================================================
   14. Project Cards
   ========================================================================== */
.project-card {
    background: white;
    border-radius: 12px;
    padding: 32px;
    margin-bottom: 24px;
    border: 1px solid #ddd;
}

.project-badge {
    display: inline-block;
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 6px 12px;
    border-radius: 4px;
    margin-bottom: 16px;
}

.project-badge.final {
    background: var(--text-primary);
    color: white;
}

.project-badge.p1 {
    background: #fef7ed;
    color: #9a6b3a;
}

.project-badge.p2 {
    background: #f0fdf4;
    color: #5c8a6b;
}

.project-card h2 {
    font-family: var(--serif);
    font-size: 32px;
    font-weight: 400;
    margin-bottom: 8px;
}

.project-card .subtitle {
    font-size: 16px;
    color: var(--text-secondary);
    margin-bottom: 24px;
}

.project-timeline {
    display: flex;
    gap: 32px;
    margin-bottom: 24px;
    padding-bottom: 24px;
    border-bottom: 1px solid #eee;
}

.timeline-item {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.timeline-label {
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
}

.timeline-value {
    font-size: 15px;
    font-weight: 500;
}

.project-description {
    font-size: 15px;
    line-height: 1.7;
    color: var(--text-secondary);
    margin-bottom: 24px;
}

.milestones {
    background: #f8f8f8;
    border-radius: 8px;
    padding: 20px 24px;
    margin-bottom: 24px;
}

.milestones-title {
    font-size: 12px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    margin-bottom: 16px;
}

.milestone-item {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 8px 0;
}

.milestone-date {
    font-size: 14px;
    font-weight: 500;
    min-width: 60px;
}

.milestone-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--text-primary);
    flex-shrink: 0;
}

.milestone-text {
    font-size: 14px;
    color: var(--text-secondary);
}

.milestone-text a {
    color: inherit;
    text-decoration: underline;
    text-underline-offset: 2px;
}

.milestone-text a:hover {
    color: var(--text-primary);
}

.project-links {
    display: flex;
    gap: 12px;
}

.project-link {
    padding: 10px 20px;
    font-size: 14px;
    font-weight: 500;
    border-radius: 6px;
    text-decoration: none;
    transition: all 0.2s;
}

.project-link.primary {
    background: var(--text-primary);
    color: white;
}

.project-link.primary:hover {
    opacity: 0.85;
}

.project-link.secondary {
    background: #f0f0f0;
    color: var(--text-primary);
}

.project-link.secondary:hover {
    background: #e5e5e5;
}

/* ==========================================================================
   15. Responsive Design
   ========================================================================== */
@media (max-width: 1200px) {
    .container {
        grid-template-columns: 1fr;
        padding: 60px 32px;
        gap: 60px;
    }

    .sidebar {
        position: relative;
        top: 0;
    }

    .site-title {
        font-size: 56px;
    }

    .sidebar-footer {
        position: relative;
        margin-top: 48px;
    }

    .post-card {
        grid-template-columns: 48px 1fr 24px;
        gap: 16px;
    }

    .post-description {
        display: none;
    }

    .post-icon {
        width: 48px;
        height: 48px;
    }

    .post-icon svg {
        width: 40px;
        height: 40px;
    }
}

@media (max-width: 1000px) {
    .calendar-header,
    .calendar-row {
        grid-template-columns: 60px 1fr 1fr 1fr;
    }

    .calendar-cell:nth-child(4) {
        display: none;
    }
}

@media (max-width: 800px) {
    .calendar-header,
    .calendar-row {
        grid-template-columns: 60px 1fr 1fr;
    }

    .calendar-cell:nth-child(4),
    .calendar-cell:last-child {
        display: none;
    }
}

@media (max-width: 600px) {
    .site-title {
        font-size: 44px;
    }

    .post-title {
        font-size: 22px;
    }

    .featured-content {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }

    .calendar-header,
    .calendar-row {
        grid-template-columns: 1fr;
    }

    .calendar-cell:first-child {
        border-bottom: 1px solid #ccc;
        padding: 12px;
    }

    .date-display {
        display: flex;
        align-items: baseline;
        gap: 6px;
    }

    .date-day {
        font-size: 18px;
    }
}