/* ==========================================================================
   Philip Hong | Accounting Learning Resources
   Site stylesheet — left-rail navigation layout
   Fonts: Source Serif 4 (headings) · Inter (Latin body) · Pretendard (Korean)
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Source+Serif+4:opsz,wght@8..60,400;8..60,500;8..60,600&display=swap');
@import url('https://cdn.jsdelivr.net/gh/orioncactus/pretendard@v1.3.9/dist/web/variable/pretendardvariable.min.css');

/* Reset & base
   ------------------------------------------------------------------------ */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --color-primary: #C41230;
    --color-primary-dark: #8E0D22;
    --color-primary-soft: #FBECEE;
    --color-ink: #1A1A2E;
    --color-ink-soft: #2E2E42;
    --color-muted: #5A5A6E;
    --color-line: #E4E4EA;
    --color-line-strong: #C8C8D0;
    --color-bg: #FAFAFB;
    --color-card: #FFFFFF;

    /* Source Serif 4 for headings; Georgia fallback */
    --font-serif: 'Source Serif 4', Georgia, 'Times New Roman', serif;
    /* Inter for Latin, Pretendard for Korean glyphs (auto fallback per char) */
    --font-sans: 'Inter', 'Pretendard Variable', Pretendard,
                 -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
                 'Helvetica Neue', Arial, sans-serif;

    --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.04),
                   0 1px 2px rgba(0, 0, 0, 0.06);
    --shadow-card-hover: 0 6px 18px rgba(0, 0, 0, 0.08),
                         0 2px 4px rgba(0, 0, 0, 0.06);

    --nav-width: 240px;
}

html { scroll-behavior: smooth; }

body {
    font-family: var(--font-sans);
    font-size: 17px;
    line-height: 1.6;
    color: var(--color-ink);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    min-height: 100vh;
}

h1, h2, h3, h4 {
    font-family: var(--font-serif);
    font-weight: normal;
    color: var(--color-ink);
    line-height: 1.25;
}

h1 { font-size: 2.4rem; letter-spacing: -0.01em; }
h2 { font-size: 1.75rem; letter-spacing: -0.005em; }
h3 { font-size: 1.3rem; }
h4 { font-size: 1.1rem; }

p { margin-bottom: 1rem; }

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color 0.15s ease;
}

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

em { font-style: italic; }

/* ==========================================================================
   LEFT-RAIL NAVIGATION
   ========================================================================== */
.side-nav {
    position: fixed;
    top: 0;
    left: 0;
    width: var(--nav-width);
    height: 100vh;
    background-color: var(--color-ink);
    display: flex;
    flex-direction: column;
    padding: 32px 0 20px;
    z-index: 20;
}

.side-nav .brand {
    padding: 0 26px 24px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    margin-bottom: 20px;
}

.side-nav .brand-name {
    color: #FFFFFF;
    font-family: var(--font-serif);
    font-size: 1.25rem;
    line-height: 1.2;
    text-decoration: none;
    display: block;
}

.side-nav .brand-name:hover {
    color: #FFFFFF;
    text-decoration: none;
}

.side-nav .brand-credentials {
    color: rgba(255, 255, 255, 0.55);
    font-size: 0.7rem;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    margin-top: 6px;
}

.side-nav .nav-list {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    flex-direction: column;
}

.side-nav .nav-list a {
    display: block;
    padding: 14px 26px;
    color: #E4E4EA;
    font-size: 0.9rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    text-decoration: none;
    border-left: 3px solid transparent;
    transition: background-color 0.15s ease, color 0.15s ease,
                border-left-color 0.15s ease;
}

.side-nav .nav-list a:hover {
    background-color: rgba(255, 255, 255, 0.06);
    color: #FFFFFF;
    text-decoration: none;
}

.side-nav .nav-list a.active {
    color: #FFFFFF;
    border-left-color: var(--color-primary);
    background-color: rgba(196, 18, 48, 0.12);
}

.side-nav .nav-footer {
    margin-top: auto;
    padding: 20px 26px 0;
    color: rgba(255, 255, 255, 0.4);
    font-size: 0.72rem;
    letter-spacing: 0.02em;
    border-top: 1px solid rgba(255, 255, 255, 0.08);
}

/* Mobile hamburger — fixed top-left */
.mobile-menu-toggle {
    display: none;
    position: fixed;
    top: 14px;
    left: 14px;
    z-index: 30;
    background: var(--color-ink);
    color: #FFFFFF;
    border: none;
    padding: 10px 14px;
    font-size: 1.3rem;
    line-height: 1;
    cursor: pointer;
}

.mobile-menu-toggle:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.nav-backdrop {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.4);
    z-index: 15;
}

.nav-backdrop.visible { display: block; }

/* ==========================================================================
   MAIN CONTENT AREA — offset by nav width
   ========================================================================== */
.main-content {
    margin-left: var(--nav-width);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 960px;
    margin: 0 auto;
    padding: 48px 40px 64px;
    width: 100%;
    flex: 1;
}

/* ==========================================================================
   LANDING PAGE — left-aligned hero + course cards
   ========================================================================== */
.landing-hero {
    padding-top: 8px;
    padding-bottom: 36px;
    margin-bottom: 36px;
    border-bottom: 1px solid var(--color-line);
}

.landing-name {
    font-family: var(--font-serif);
    font-size: 2.7rem;
    color: var(--color-ink);
    line-height: 1.15;
    margin-bottom: 18px;
    letter-spacing: -0.01em;
}

.landing-divider {
    width: 60px;
    height: 3px;
    background-color: var(--color-primary);
    margin: 0 0 18px 0;
}

.landing-title {
    font-family: var(--font-serif);
    font-size: 1.45rem;
    color: var(--color-ink-soft);
    font-style: italic;
    margin-bottom: 8px;
}

.landing-tagline {
    color: var(--color-muted);
    font-size: 1rem;
    letter-spacing: 0.02em;
    margin-bottom: 0;
}

/* Course cards on landing page */
.courses-list {
    margin-top: 4px;
}

.course-card {
    display: flex;
    align-items: center;
    background: var(--color-card);
    border: 1px solid var(--color-line);
    padding: 22px 26px;
    text-decoration: none;
    color: inherit;
    margin-bottom: 14px;
    transition: transform 0.15s ease, box-shadow 0.15s ease,
                border-color 0.15s ease;
    position: relative;
}

.course-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: 4px;
    background-color: var(--color-primary);
    transform: scaleY(0);
    transform-origin: top;
    transition: transform 0.2s ease;
}

.course-card:hover {
    box-shadow: var(--shadow-card-hover);
    border-color: var(--color-line-strong);
    text-decoration: none;
    color: inherit;
}

.course-card:hover::before { transform: scaleY(1); }

.course-card .icon {
    font-size: 1.7rem;
    line-height: 1;
    margin-right: 16px;
    flex-shrink: 0;
}

.course-card .body { flex: 1; min-width: 0; }

.course-card h3 {
    font-family: var(--font-serif);
    font-size: 1.2rem;
    color: var(--color-ink);
    margin-bottom: 2px;
}

.course-card .description {
    color: var(--color-muted);
    font-size: 0.9rem;
    margin-bottom: 0;
}

.course-card .action {
    color: var(--color-primary);
    font-size: 0.82rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    white-space: nowrap;
    margin-left: 20px;
    flex-shrink: 0;
}

.course-card .arrow {
    display: inline-block;
    margin-left: 4px;
    transition: transform 0.15s ease;
}

.course-card:hover .arrow { transform: translateX(4px); }

.course-card.upcoming {
    opacity: 0.55;
    pointer-events: none;
}

.course-card.upcoming::before { background-color: var(--color-line-strong); }

/* ==========================================================================
   BREADCRUMB
   ========================================================================== */
.breadcrumb {
    font-size: 0.88rem;
    color: var(--color-muted);
    margin-bottom: 20px;
    letter-spacing: 0.02em;
}

.breadcrumb a { color: var(--color-muted); }
.breadcrumb a:hover { color: var(--color-primary); text-decoration: underline; }
.breadcrumb .separator { margin: 0 8px; color: var(--color-line-strong); }

/* ==========================================================================
   PAGE HEADER (minimal — used on Courses, About, weeks)
   ========================================================================== */
.page-header {
    margin-bottom: 32px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--color-line);
}

.page-header h1 {
    margin-bottom: 0;
}

.page-header .eyebrow {
    text-transform: uppercase;
    letter-spacing: 0.12em;
    font-size: 0.78rem;
    color: var(--color-primary);
    font-weight: 600;
    margin-bottom: 8px;
}

/* ==========================================================================
   COURSES PAGE — week card grid
   ========================================================================== */
.week-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 16px;
}

.week-card {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: var(--color-card);
    border: 1px solid var(--color-line);
    padding: 22px 24px;
    text-decoration: none;
    color: inherit;
    transition: transform 0.15s ease, box-shadow 0.15s ease,
                border-color 0.15s ease;
    position: relative;
}

.week-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background-color: var(--color-primary);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.2s ease;
}

.week-card:hover {
    box-shadow: var(--shadow-card-hover);
    border-color: var(--color-line-strong);
    text-decoration: none;
    color: inherit;
}

.week-card:hover::before { transform: scaleX(1); }

.week-card .week-number {
    font-family: var(--font-serif);
    font-size: 1.2rem;
    color: var(--color-ink);
    letter-spacing: 0.02em;
}

.week-card .open-link {
    font-size: 0.85rem;
    color: var(--color-primary);
    letter-spacing: 0.06em;
    text-transform: uppercase;
    white-space: nowrap;
}

.week-card .arrow {
    display: inline-block;
    margin-left: 4px;
    transition: transform 0.15s ease;
}

.week-card:hover .arrow { transform: translateX(4px); }

/* ==========================================================================
   WEEK PAGE — language toggle + lecture blocks
   ========================================================================== */
.language-toggle {
    display: inline-flex;
    align-items: center;
    background: #FFFFFF;
    border: 1px solid var(--color-line);
    padding: 4px;
    margin-bottom: 28px;
}

.language-toggle button {
    background: transparent;
    border: none;
    padding: 8px 20px;
    font-family: var(--font-sans);
    font-size: 0.95rem;
    color: var(--color-muted);
    cursor: pointer;
    letter-spacing: 0.02em;
    transition: background-color 0.15s ease, color 0.15s ease;
}

.language-toggle button:hover { color: var(--color-ink); }

.language-toggle button.active {
    background-color: var(--color-ink);
    color: #FFFFFF;
}

.language-toggle .divider {
    width: 1px;
    height: 16px;
    background: var(--color-line);
    margin: 0 2px;
}

.resources { display: none; }
.resources.active { display: block; }

/* Lecture block */
.lecture-block {
    margin-bottom: 34px;
}

.lecture-block h3 {
    font-family: var(--font-serif);
    font-size: 1.3rem;
    color: var(--color-ink);
    margin-bottom: 4px;
}

.lecture-divider {
    width: 36px;
    height: 2px;
    background-color: var(--color-primary);
    margin: 6px 0 14px;
}

.lecture-topic {
    color: var(--color-muted);
    font-size: 0.9rem;
    font-style: italic;
    margin: -6px 0 12px;
}

.lecture-items {
    list-style: none;
    padding: 0;
    margin: 0;
}

.lecture-items li {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 20px;
    background: #FFFFFF;
    border: 1px solid var(--color-line);
    margin-bottom: 6px;
    transition: border-color 0.15s ease;
    gap: 12px;
}

.lecture-items li:hover:not(.disabled) {
    border-color: var(--color-line-strong);
}

.lecture-items .item-label {
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--color-ink);
    min-width: 0;
}

.lecture-items .item-label .icon {
    font-size: 1.1rem;
    line-height: 1;
    flex-shrink: 0;
}

.lecture-items .file-link {
    color: var(--color-primary);
    font-size: 0.85rem;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    text-decoration: none;
    white-space: nowrap;
    flex-shrink: 0;
}

.lecture-items .file-link:hover {
    color: var(--color-primary-dark);
    text-decoration: underline;
}

.lecture-items li.disabled {
    opacity: 0.6;
}

.lecture-items .placeholder {
    color: var(--color-muted);
    font-size: 0.82rem;
    font-style: italic;
    letter-spacing: 0.02em;
    white-space: nowrap;
}

/* ==========================================================================
   SCHEDULE PAGE — view-only table
   ========================================================================== */
.schedule-intro {
    color: var(--color-muted);
    font-size: 0.95rem;
    margin-bottom: 20px;
}

.schedule-scroll {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    border: 1px solid var(--color-line);
    background: #FFFFFF;
}

.schedule-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.92rem;
    min-width: 640px;
}

.schedule-table th,
.schedule-table td {
    text-align: left;
    padding: 12px 16px;
    border-bottom: 1px solid var(--color-line);
    vertical-align: top;
}

.schedule-table thead th {
    background: var(--color-ink);
    color: #FFFFFF;
    font-family: var(--font-sans);
    font-weight: 600;
    font-size: 0.8rem;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    white-space: nowrap;
}

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

.schedule-table tbody tr:hover { background: var(--color-bg); }

.schedule-table .col-session { white-space: nowrap; font-weight: 600; width: 1%; }
.schedule-table .col-date { white-space: nowrap; width: 1%; }
.schedule-table .col-due { white-space: nowrap; width: 1%; }

/* Body-cell colors only — header cells stay white (set above) */
.schedule-table tbody .col-session { color: var(--color-ink); }
.schedule-table tbody .col-date { color: var(--color-muted); }
.schedule-table tbody .col-due { color: var(--color-primary-dark); }

.schedule-table tr.exam-row td {
    background: var(--color-primary-soft);
    font-weight: 600;
    color: var(--color-primary-dark);
}

.schedule-table tr.exam-row:hover td { background: var(--color-primary-soft); }

.schedule-table .topic-sub {
    display: block;
    color: var(--color-muted);
    font-size: 0.85rem;
    font-style: italic;
    margin-top: 3px;
    font-weight: 400;
}

/* Prev/Next week nav */
.prev-next-nav {
    display: flex;
    justify-content: space-between;
    gap: 16px;
    margin-top: 40px;
    padding-top: 24px;
    border-top: 1px solid var(--color-line);
}

.prev-next-nav a,
.prev-next-nav span {
    display: flex;
    flex-direction: column;
    padding: 12px 18px;
    border: 1px solid var(--color-line);
    background: #FFFFFF;
    color: var(--color-ink);
    text-decoration: none;
    min-width: 160px;
    transition: border-color 0.15s ease;
}

.prev-next-nav a:hover {
    border-color: var(--color-primary);
    color: var(--color-ink);
    text-decoration: none;
}

.prev-next-nav .direction {
    font-size: 0.72rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--color-muted);
    margin-bottom: 2px;
}

.prev-next-nav .title {
    font-family: var(--font-serif);
    font-size: 0.95rem;
}

.prev-next-nav .next {
    text-align: right;
    margin-left: auto;
}

.prev-next-nav .disabled {
    opacity: 0.4;
    pointer-events: none;
}

/* ==========================================================================
   ABOUT PAGE — photo + bio + CV
   ========================================================================== */
.about-hero {
    display: flex;
    align-items: center;
    gap: 32px;
    margin-bottom: 32px;
    padding-bottom: 24px;
    border-bottom: 1px solid var(--color-line);
}

.about-hero .portrait {
    width: 200px;
    height: auto;
    border: 1px solid var(--color-line);
    background: #FFFFFF;
    padding: 4px;
    flex-shrink: 0;
    display: block;
}

.about-hero .about-info { flex: 1; min-width: 0; }

.about-hero h1 {
    font-size: 2rem;
    margin-bottom: 6px;
    line-height: 1.15;
}

.about-hero .about-affiliation {
    color: var(--color-muted);
    font-size: 1rem;
}

.about-hero .about-affiliation .divider-dot {
    color: var(--color-primary);
    margin: 0 8px;
}

.prose {
    max-width: 720px;
}

.prose p {
    font-size: 1.02rem;
    color: var(--color-ink);
    margin-bottom: 1.2rem;
}

.prose h2 {
    margin-top: 0;
    margin-bottom: 12px;
    font-size: 1.35rem;
    padding-bottom: 6px;
    border-bottom: 2px solid var(--color-line);
}

/* CV buttons (reused from before) */
.cta-button {
    display: inline-block;
    padding: 12px 30px;
    background-color: var(--color-primary);
    color: #FFFFFF;
    font-family: var(--font-sans);
    font-size: 0.95rem;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    text-decoration: none;
    border: 2px solid var(--color-primary);
    transition: background-color 0.15s ease, color 0.15s ease,
                border-color 0.15s ease;
}

.cta-button:hover {
    background-color: var(--color-primary-dark);
    border-color: var(--color-primary-dark);
    color: #FFFFFF;
    text-decoration: none;
}

.cta-button.secondary {
    background-color: transparent;
    color: var(--color-ink);
    border-color: var(--color-ink);
}

.cta-button.secondary:hover {
    background-color: var(--color-ink);
    color: #FFFFFF;
}

.cv-actions {
    display: flex;
    gap: 12px;
    margin-top: 20px;
    margin-bottom: 8px;
    flex-wrap: wrap;
}

.cv-meta {
    color: var(--color-muted);
    font-size: 0.88rem;
    margin-top: 6px;
    font-style: italic;
}

/* ==========================================================================
   RESPONSIVE — Mobile ( < 768px )
   ========================================================================== */
@media (max-width: 767px) {
    h1 { font-size: 1.8rem; }
    h2 { font-size: 1.4rem; }

    /* Side nav slides in from left */
    .side-nav {
        transform: translateX(-100%);
        transition: transform 0.22s ease;
        width: 240px;
    }

    .side-nav.open { transform: translateX(0); }

    .mobile-menu-toggle { display: block; }

    .main-content { margin-left: 0; }

    .container { padding: 60px 20px 40px; }

    .landing-name { font-size: 2rem; }
    .landing-title { font-size: 1.15rem; }

    .course-card {
        flex-direction: column;
        align-items: flex-start;
        padding: 20px 22px;
    }
    .course-card .icon { margin-right: 0; margin-bottom: 10px; }
    .course-card .action { margin-left: 0; margin-top: 12px; }

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

    .about-hero {
        flex-direction: column;
        text-align: center;
        gap: 22px;
    }
    .about-hero .portrait { width: 170px; }

    .prev-next-nav { flex-direction: column; }
    .prev-next-nav a,
    .prev-next-nav span { min-width: 0; width: 100%; }
    .prev-next-nav .next { text-align: left; margin-left: 0; }

    .lecture-items li {
        flex-direction: column;
        align-items: flex-start;
        gap: 6px;
    }
}

/* ==========================================================================
   FOOTER
   ========================================================================== */
.site-footer {
    padding: 22px 40px;
    text-align: center;
    font-size: 0.8rem;
    color: var(--color-muted);
    border-top: 1px solid var(--color-line);
    background: #FFFFFF;
}

@media (max-width: 767px) {
    .site-footer { padding: 22px 20px; }
}

/* ==========================================================================
   ACCESS GATE (client-side friction — not real security)
   ========================================================================== */
body.requires-access {
    overflow: hidden;
}

body.requires-access .main-content {
    filter: blur(6px);
    pointer-events: none;
    user-select: none;
}

body.requires-access .side-nav {
    pointer-events: none;
    opacity: 0.5;
}

.access-gate {
    position: fixed;
    inset: 0;
    background: rgba(26, 26, 46, 0.55);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
    padding: 20px;
    -webkit-backdrop-filter: blur(4px);
    backdrop-filter: blur(4px);
}

.access-card {
    background: #FFFFFF;
    border: 1px solid var(--color-line);
    border-top: 4px solid var(--color-primary);
    padding: 36px 40px 32px;
    max-width: 420px;
    width: 100%;
    text-align: center;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.25);
}

.access-card h2 {
    font-family: var(--font-serif);
    font-size: 1.5rem;
    margin-bottom: 8px;
    color: var(--color-ink);
}

.access-card p {
    color: var(--color-muted);
    font-size: 0.94rem;
    margin-bottom: 22px;
    line-height: 1.5;
}

.access-form {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.access-input {
    padding: 13px 16px;
    font-size: 1.35rem;
    text-align: center;
    letter-spacing: 0.35em;
    font-family: var(--font-sans);
    border: 1px solid var(--color-line);
    background: #FAFAFB;
    color: var(--color-ink);
    outline: none;
    transition: border-color 0.15s ease, background-color 0.15s ease;
}

.access-input:focus {
    border-color: var(--color-primary);
    background: #FFFFFF;
}

.access-submit {
    padding: 12px 24px;
    background-color: var(--color-primary);
    color: #FFFFFF;
    font-family: var(--font-sans);
    font-size: 0.9rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    border: none;
    cursor: pointer;
    transition: background-color 0.15s ease;
}

.access-submit:hover {
    background-color: var(--color-primary-dark);
}

.access-error {
    color: var(--color-primary);
    font-size: 0.88rem;
    margin-top: 14px;
}

@keyframes access-shake {
    0%, 100% { transform: translateX(0); }
    20%, 60% { transform: translateX(-8px); }
    40%, 80% { transform: translateX(8px); }
}

.access-card.shake {
    animation: access-shake 0.4s ease-in-out;
}

@media (max-width: 480px) {
    .access-card { padding: 28px 24px; }
    .access-card h2 { font-size: 1.3rem; }
}