/* ===================================================
   LabWeb - Main Stylesheet
   Design Research Lab Theme
   =================================================== */

/* ===== Custom Properties ===== */
:root {
    --color-bg:          #ffffff;
    --color-bg-secondary:#f5f5f5;
    --color-bg-dark:     #111111;
    --color-text:        #111111;
    --color-text-muted:  #6b6b6b;
    --color-text-light:  #999999;
    --color-accent:      #1744cf;
    --color-accent-hover:#0f32a8;
    --color-border:      #e8e8e8;
    --color-border-dark: #d0d0d0;
    --color-error:       #dc2626;
    --color-error-bg:    #fef2f2;
    --color-success:     #16a34a;

    --font-sans: 'Inter', 'Noto Sans JP', -apple-system, BlinkMacSystemFont, 'Helvetica Neue', sans-serif;
    --font-mono: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;

    --radius-sm:   4px;
    --radius-md:   8px;
    --radius-lg:   12px;
    --radius-full: 9999px;

    --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
    --shadow-lg: 0 8px 24px rgba(0,0,0,0.10);

    --header-height: 64px;
    --max-width:     1200px;
    --narrow-width:  760px;

    --transition: 0.2s ease;
}

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

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    font-size: 1rem;
    line-height: 1.7;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img, video {
    display: block;
    max-width: 100%;
    height: auto;
}

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color var(--transition), opacity var(--transition);
}
a:hover { color: var(--color-accent-hover); }

ul, ol { list-style: none; }

button {
    cursor: pointer;
    border: none;
    background: none;
    font-family: var(--font-sans);
}

.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;
}

/* ===== Layout ===== */
.container {
    width: 100%;
    max-width: var(--max-width);
    margin-inline: auto;
    padding-inline: 24px;
}
.container--narrow {
    max-width: var(--narrow-width);
}

.main-content {
    min-height: calc(100vh - var(--header-height) - 200px);
    padding-top: 60px;
    padding-bottom: 80px;
}
.home .main-content {
    padding-top: 0;
}

#page-wrapper {
    padding-top: var(--header-height);
}

.section {
    padding-block: 64px;
}

/* ===== Header ===== */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    height: var(--header-height);
    background: rgba(255,255,255,0.95);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border-bottom: 1px solid transparent;
    transition: border-color var(--transition), box-shadow var(--transition);
}
.site-header.is-scrolled {
    border-bottom-color: var(--color-border);
    box-shadow: var(--shadow-sm);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.site-logo {
    display: flex;
    flex-direction: column;
    line-height: 1.2;
    color: var(--color-text);
    text-decoration: none;
}
.site-logo:hover { color: var(--color-text); opacity: 0.7; }
.logo-primary {
    font-size: 1.05rem;
    font-weight: 700;
    letter-spacing: -0.01em;
}
.logo-secondary {
    font-size: 0.7rem;
    font-weight: 400;
    color: var(--color-text-muted);
    letter-spacing: 0.05em;
}

.main-nav .nav-list {
    display: flex;
    gap: 2rem;
    align-items: center;
}
.main-nav .nav-list a {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text);
    letter-spacing: 0.01em;
    padding: 4px 0;
    position: relative;
}
.main-nav .nav-list a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--color-accent);
    transition: width var(--transition);
}
.main-nav .nav-list a:hover::after,
.main-nav .nav-list .current-menu-item a::after {
    width: 100%;
}
.main-nav .nav-list a:hover { color: var(--color-text); }

/* Mobile menu toggle */
.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 8px;
    margin-right: -8px;
}
.menu-toggle-bar {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--color-text);
    border-radius: 2px;
    transition: transform var(--transition), opacity var(--transition);
}
.menu-toggle.is-active .menu-toggle-bar:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}
.menu-toggle.is-active .menu-toggle-bar:nth-child(2) {
    opacity: 0;
}
.menu-toggle.is-active .menu-toggle-bar:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* ===== Billboard ===== */
.billboard {
    position: relative;
    min-height: 80vh;
    background-color: var(--color-bg-dark);
    overflow: hidden;
}
.billboard-slide {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    background-size: cover;
    background-position: center;
    opacity: 0;
    transition: opacity 0.9s ease;
    pointer-events: none;
}
.billboard-slide.is-active {
    opacity: 1;
    pointer-events: auto;
    position: relative;        /* first active slide sets height */
    min-height: 80vh;
}
.billboard-slide-video {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: 0;
}
.billboard-overlay {
    display: none;
}
.billboard-content {
    position: relative;
    z-index: 2;
    color: #ffffff;
    max-width: 700px;
    padding-block: 80px;
}
.billboard-title {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 700;
    line-height: 1.15;
    letter-spacing: -0.02em;
    margin-bottom: 1rem;
}
.billboard-text {
    font-size: clamp(1rem, 2vw, 1.25rem);
    font-weight: 300;
    line-height: 1.6;
    opacity: 0.9;
}
/* Carousel navigation */
.billboard-nav {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    z-index: 10;
    background: rgba(255, 255, 255, 0.2);
    border: none;
    color: #ffffff;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.75rem;
    line-height: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.2s;
}
.billboard-nav:hover {
    background: rgba(255, 255, 255, 0.38);
}
.billboard-prev { left: 1.25rem; }
.billboard-next { right: 1.25rem; }
.billboard-dots {
    position: absolute;
    bottom: 1.25rem;
    left: 50%;
    transform: translateX(-50%);
    z-index: 10;
    display: flex;
    gap: 0.5rem;
}
.billboard-dot {
    width: 9px;
    height: 9px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.5);
    border: none;
    cursor: pointer;
    padding: 0;
    transition: background 0.25s, transform 0.25s;
}
.billboard-dot.is-active {
    background: #ffffff;
    transform: scale(1.3);
}

/* Billboard small variant */
.billboard--small .billboard-slide.is-active {
    min-height: 40vh;
}

/* ===== Projects Archive ===== */
.projects-section {
    margin-bottom: 4rem;
}
.projects-section-title {
    font-size: clamp(1.1rem, 2.5vw, 1.4rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: 2rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--color-text);
}

/* ===== Project List ===== */
.project-list {
    display: flex;
    flex-direction: column;
    gap: 0;
}

/* ===== Project Card (row layout) ===== */
.project-card--row {
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    transition: background var(--transition);
}
.project-card--row:first-child {
    border-top: 1px solid var(--color-border);
}
.project-card--row:hover {
    background: var(--color-bg-secondary);
}
.project-card--row .project-card-link {
    display: grid;
    grid-template-columns: 320px 1fr;
    text-decoration: none;
    color: inherit;
    min-height: 200px;
}
.project-card--row .project-card-thumbnail {
    overflow: hidden;
    background: var(--color-bg-secondary);
    aspect-ratio: unset;
}
.project-card--row .project-card-thumbnail img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.5s ease;
    display: block;
}
.project-card--row:hover .project-card-thumbnail img {
    transform: scale(1.04);
}
.project-card--row .project-card-thumbnail-placeholder {
    width: 100%;
    height: 100%;
    min-height: 200px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--color-text-light);
    background: var(--color-bg-secondary);
}
.project-card--row .project-card-body {
    padding: 28px 32px;
    display: flex;
    flex-direction: column;
    gap: 10px;
    justify-content: center;
}
.project-card--row .project-card-title {
    font-size: 1.15rem;
    font-weight: 700;
    line-height: 1.4;
    color: var(--color-text);
}
.project-card--row .project-card-summary {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    line-height: 1.7;
    flex: 1;
}
.project-card--row .project-card-more {
    display: inline-block;
    margin-top: 4px;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--color-accent);
    text-decoration: none;
}

/* ===== Project Detail ===== */
.project-section {
    margin-bottom: 3rem;
    padding-bottom: 3rem;
    border-bottom: 1px solid var(--color-border);
}
.project-section:last-child {
    border-bottom: none;
}
.project-section-title {
    font-size: 1.1rem;
    font-weight: 700;
    letter-spacing: -0.01em;
    margin-bottom: 1.25rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--color-text);
}
.project-summary-text {
    font-size: 1rem;
    line-height: 1.8;
    color: var(--color-text);
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.625rem 1.5rem;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 600;
    line-height: 1.4;
    letter-spacing: 0.01em;
    text-align: center;
    white-space: nowrap;
    cursor: pointer;
    transition: background var(--transition), color var(--transition), border-color var(--transition), box-shadow var(--transition);
    text-decoration: none;
}
.btn--primary {
    background: var(--color-accent);
    color: #fff;
    border: 2px solid var(--color-accent);
}
.btn--primary:hover {
    background: var(--color-accent-hover);
    border-color: var(--color-accent-hover);
    color: #fff;
}
.btn--outline {
    background: transparent;
    color: var(--color-accent);
    border: 2px solid var(--color-accent);
}
.btn--outline:hover {
    background: var(--color-accent);
    color: #fff;
}
.btn--ghost {
    background: transparent;
    color: var(--color-text-muted);
    border: 2px solid var(--color-border);
}
.btn--ghost:hover {
    border-color: var(--color-text-muted);
    color: var(--color-text);
}
.btn--download {
    background: var(--color-bg-secondary);
    color: var(--color-text);
    border: 2px solid var(--color-border);
    font-weight: 500;
}
.btn--download:hover {
    background: var(--color-text);
    color: #fff;
    border-color: var(--color-text);
}
.btn--full { width: 100%; justify-content: center; }
.btn--sm { padding: 0.375rem 1rem; font-size: 0.8rem; }

/* ===== Tags ===== */
.tag {
    display: inline-block;
    padding: 2px 10px;
    background: var(--color-bg-secondary);
    color: var(--color-text-muted);
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: var(--radius-full);
    transition: background var(--transition), color var(--transition);
    text-decoration: none;
}
a.tag:hover, .tag.is-active {
    background: var(--color-accent);
    color: #fff;
}

/* ===== Section Titles ===== */
.section-title {
    font-size: clamp(1.25rem, 3vw, 1.75rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: 2rem;
}
.page-title {
    font-size: clamp(1.5rem, 4vw, 2.25rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: 0.5rem;
}
.section-footer {
    margin-top: 2.5rem;
    text-align: center;
}

/* ===== Posts Grid ===== */
.posts-grid {
    display: grid;
    gap: 24px;
}
.posts-grid--4col { grid-template-columns: repeat(4, 1fr); }
.posts-grid--3col { grid-template-columns: repeat(3, 1fr); }
.posts-grid--projects { grid-template-columns: repeat(2, 1fr); }

/* ===== Post Card ===== */
.post-card {
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    overflow: hidden;
    transition: box-shadow var(--transition), transform var(--transition), border-color var(--transition);
}
.post-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
    border-color: var(--color-border-dark);
}
.post-card-link {
    display: block;
    text-decoration: none;
    color: inherit;
}
.post-card-thumbnail {
    aspect-ratio: 3/2;
    overflow: hidden;
    background: var(--color-bg-secondary);
}
.post-card-thumbnail img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.4s ease;
}
.post-card:hover .post-card-thumbnail img {
    transform: scale(1.03);
}
.post-card-thumbnail-placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    font-weight: 700;
    color: var(--color-text-light);
    background: var(--color-bg-secondary);
}
.post-card-body {
    padding: 16px;
}
.post-card-title {
    font-size: 0.9rem;
    font-weight: 600;
    line-height: 1.4;
    color: var(--color-text);
    margin-bottom: 6px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}
.post-card-excerpt {
    font-size: 0.8rem;
    color: var(--color-text-muted);
    line-height: 1.5;
    margin-bottom: 10px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}
.post-card-meta {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}
.post-card-date {
    font-size: 0.75rem;
    color: var(--color-text-light);
    font-variant-numeric: tabular-nums;
}
.post-card-tags {
    display: flex;
    gap: 4px;
    flex-wrap: wrap;
}

/* ===== Pagination ===== */
.pagination {
    margin-top: 48px;
    display: flex;
    justify-content: center;
}
.pagination ul {
    display: flex;
    gap: 6px;
    align-items: center;
    flex-wrap: wrap;
}
.pagination ul li a,
.pagination ul li span {
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 38px;
    height: 38px;
    padding: 0 10px;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 500;
    border: 1px solid var(--color-border);
    color: var(--color-text);
    text-decoration: none;
    transition: background var(--transition), color var(--transition), border-color var(--transition);
}
.pagination ul li a:hover {
    background: var(--color-text);
    color: #fff;
    border-color: var(--color-text);
}
.pagination ul li .current {
    background: var(--color-accent);
    color: #fff;
    border-color: var(--color-accent);
}

/* ===== Archive Layout ===== */
.archive-header {
    margin-bottom: 2rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid var(--color-border);
}
.archive-title {
    font-size: clamp(1.4rem, 3vw, 2rem);
    font-weight: 700;
    letter-spacing: -0.02em;
}
.archive-layout {
    display: grid;
    grid-template-columns: 240px 1fr;
    gap: 48px;
    align-items: start;
}
.archive-sidebar {
    position: sticky;
    top: calc(var(--header-height) + 24px);
}
.filter-block {
    margin-bottom: 2rem;
}
.filter-block:last-child { margin-bottom: 0; }
.filter-title {
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--color-text-muted);
    margin-bottom: 0.75rem;
}
.filter-list {
    display: flex;
    flex-direction: column;
    gap: 2px;
}
.filter-link {
    display: block;
    padding: 6px 10px;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    color: var(--color-text-muted);
    text-decoration: none;
    transition: background var(--transition), color var(--transition);
}
.filter-link:hover, .filter-link.is-active {
    background: var(--color-bg-secondary);
    color: var(--color-text);
}
.filter-link.is-active { font-weight: 600; }
.filter-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

/* Search form */
.search-form-inner {
    display: flex;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    overflow: hidden;
    transition: border-color var(--transition);
}
.search-form-inner:focus-within {
    border-color: var(--color-accent);
}
.search-input {
    flex: 1;
    padding: 8px 12px;
    border: none;
    outline: none;
    font-size: 0.875rem;
    font-family: var(--font-sans);
    background: transparent;
}
.search-submit {
    padding: 8px 12px;
    background: transparent;
    border: none;
    color: var(--color-text-muted);
    transition: color var(--transition);
    cursor: pointer;
}
.search-submit:hover { color: var(--color-accent); }

/* ===== Single Article ===== */
.single-header {
    margin-bottom: 2.5rem;
}
.single-meta {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}
.single-date {
    font-size: 0.8rem;
    color: var(--color-text-muted);
    font-variant-numeric: tabular-nums;
}
.single-tags {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
}
.single-title {
    font-size: clamp(1.6rem, 4vw, 2.5rem);
    font-weight: 700;
    line-height: 1.2;
    letter-spacing: -0.02em;
    margin-bottom: 1.5rem;
}
.single-thumbnail {
    border-radius: var(--radius-md);
    overflow: hidden;
    margin-bottom: 2rem;
}
.single-thumbnail img {
    width: 100%;
    aspect-ratio: 16/9;
    object-fit: cover;
}
.post-navigation {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--color-border);
}
.post-nav-next { text-align: right; }
.post-navigation a {
    font-size: 0.875rem;
    font-weight: 500;
}

/* ===== Entry Content (rich text) ===== */
.entry-content {
    font-size: 1rem;
    line-height: 1.8;
    color: var(--color-text);
}
.entry-content h1,
.entry-content h2,
.entry-content h3,
.entry-content h4,
.entry-content h5,
.entry-content h6 {
    font-weight: 700;
    line-height: 1.3;
    letter-spacing: -0.01em;
    margin-top: 2em;
    margin-bottom: 0.75em;
}
.entry-content h2 { font-size: 1.5rem; }
.entry-content h3 { font-size: 1.25rem; }
.entry-content h4 { font-size: 1.1rem; }
.entry-content p { margin-bottom: 1.25em; }
.entry-content ul, .entry-content ol {
    margin-bottom: 1.25em;
    padding-left: 1.5em;
    list-style: revert;
}
.entry-content li { margin-bottom: 0.5em; }
.entry-content img {
    border-radius: var(--radius-md);
    margin-block: 1.5em;
}
.entry-content a {
    color: var(--color-accent);
    text-decoration: underline;
    text-underline-offset: 2px;
}
.entry-content blockquote {
    border-left: 3px solid var(--color-border-dark);
    padding-left: 1.25rem;
    margin-block: 1.5em;
    color: var(--color-text-muted);
    font-style: italic;
}
.entry-content code {
    font-family: var(--font-mono);
    font-size: 0.875em;
    background: var(--color-bg-secondary);
    padding: 2px 6px;
    border-radius: var(--radius-sm);
}
.entry-content pre {
    background: var(--color-bg-dark);
    color: #e5e7eb;
    padding: 1.25rem;
    border-radius: var(--radius-md);
    overflow-x: auto;
    margin-block: 1.5em;
    font-size: 0.875rem;
    line-height: 1.6;
}
.entry-content pre code {
    background: none;
    padding: 0;
    color: inherit;
}
.entry-content table {
    width: 100%;
    border-collapse: collapse;
    margin-block: 1.5em;
    font-size: 0.9rem;
}
.entry-content th, .entry-content td {
    padding: 10px 14px;
    border: 1px solid var(--color-border);
    text-align: left;
}
.entry-content th {
    background: var(--color-bg-secondary);
    font-weight: 600;
}
.entry-content hr {
    border: none;
    border-top: 1px solid var(--color-border);
    margin-block: 2em;
}

/* ===== Password Gate ===== */
.password-gate {
    min-height: calc(100vh - var(--header-height));
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 40px 24px;
    background: var(--color-bg-secondary);
}
.password-gate-inner {
    width: 100%;
    max-width: 400px;
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 40px;
    text-align: center;
    box-shadow: var(--shadow-lg);
}
.password-gate-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 64px;
    height: 64px;
    background: var(--color-bg-secondary);
    border-radius: var(--radius-full);
    color: var(--color-text-muted);
    margin-bottom: 1.5rem;
}
.password-gate-title {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: 0.75rem;
}
.password-gate-desc {
    font-size: 0.875rem;
    color: var(--color-text-muted);
    line-height: 1.6;
    margin-bottom: 1.5rem;
}
.password-form {
    display: flex;
    flex-direction: column;
    gap: 12px;
}
.password-form-field {
    position: relative;
}
.password-input {
    width: 100%;
    padding: 12px 44px 12px 14px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    font-family: var(--font-sans);
    outline: none;
    transition: border-color var(--transition), box-shadow var(--transition);
}
.password-input:focus {
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(23,68,207,0.1);
}
.password-toggle {
    position: absolute;
    right: 12px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--color-text-light);
    transition: color var(--transition);
}
.password-toggle:hover { color: var(--color-text); }

/* Alert */
.alert {
    padding: 12px 16px;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    margin-bottom: 1rem;
    text-align: left;
}
.alert--error {
    background: var(--color-error-bg);
    color: var(--color-error);
    border: 1px solid #fecaca;
}

/* ===== Class Materials - Grade Badge ===== */
.class-materials-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 16px;
    margin-bottom: 2.5rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid var(--color-border);
}
.grade-badge {
    display: inline-block;
    padding: 4px 12px;
    background: var(--color-accent);
    color: #fff;
    font-size: 0.8rem;
    font-weight: 600;
    border-radius: var(--radius-full);
}

/* Grade section */
.grade-section {
    margin-bottom: 3rem;
}
.grade-section-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--color-text-muted);
    letter-spacing: 0.03em;
    margin-bottom: 1.25rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--color-border);
}

/* Course grid */
.course-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}
.course-banner {
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    overflow: hidden;
    transition: box-shadow var(--transition), transform var(--transition), border-color var(--transition);
}
.course-banner:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
    border-color: var(--color-border-dark);
}
.course-banner-link {
    display: block;
    text-decoration: none;
    color: inherit;
}
.course-banner-image {
    aspect-ratio: 16/9;
    overflow: hidden;
    background: var(--color-bg-secondary);
}
.course-banner-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.4s ease;
}
.course-banner:hover .course-banner-image img { transform: scale(1.03); }
.course-banner-placeholder {
    aspect-ratio: 16/9;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--color-bg-secondary), #e0e0e0);
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--color-text-light);
}
.course-banner-body {
    padding: 18px;
}
.course-banner-title {
    font-size: 1rem;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 8px;
    line-height: 1.4;
}
.course-banner-excerpt {
    font-size: 0.8rem;
    color: var(--color-text-muted);
    line-height: 1.5;
    margin-bottom: 12px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}
.course-banner-arrow {
    font-size: 0.8rem;
    color: var(--color-accent);
    font-weight: 500;
}

/* ===== Course Overview ===== */
.course-section {
    margin-bottom: 3rem;
    padding-bottom: 3rem;
    border-bottom: 1px solid var(--color-border);
}
.course-section:last-child {
    border-bottom: none;
}
.course-section-title {
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: -0.01em;
    margin-bottom: 1.25rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--color-text);
    display: inline-block;
}
.course-notes {
    background: var(--color-bg-secondary);
    padding: 1.25rem 1.5rem;
    border-radius: var(--radius-md);
    border-left: 4px solid var(--color-accent);
    font-size: 0.9rem;
    line-height: 1.7;
}

/* Lesson table */
.lesson-table-wrapper {
    overflow-x: auto;
    border-radius: var(--radius-md);
    border: 1px solid var(--color-border);
}
.lesson-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
}
.lesson-table thead tr {
    background: var(--color-bg-secondary);
}
.lesson-table th {
    padding: 12px 16px;
    font-weight: 600;
    text-align: left;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-muted);
    border-bottom: 1px solid var(--color-border);
}
.lesson-table td {
    padding: 14px 16px;
    border-bottom: 1px solid var(--color-border);
    vertical-align: middle;
}
.lesson-table tr:last-child td { border-bottom: none; }
.lesson-table tr:hover td { background: var(--color-bg-secondary); }
.lesson-table-num {
    width: 60px;
    text-align: center;
    color: var(--color-text-muted);
    font-variant-numeric: tabular-nums;
}
.lesson-table-date {
    width: 120px;
    color: var(--color-text-muted);
    font-variant-numeric: tabular-nums;
    white-space: nowrap;
}
.lesson-table-title a {
    color: var(--color-text);
    font-weight: 500;
    text-decoration: none;
}
.lesson-table-title a:hover {
    color: var(--color-accent);
    text-decoration: underline;
    text-underline-offset: 2px;
}

/* Download buttons */
.download-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

/* Custom link buttons */
.custom-link-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

/* ===== Lesson (授業内容) ===== */
.breadcrumb {
    margin-bottom: 2rem;
}
.breadcrumb ol {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
    font-size: 0.8rem;
    color: var(--color-text-muted);
}
.breadcrumb ol li + li::before {
    content: '/';
    color: var(--color-border-dark);
}
.breadcrumb a { color: var(--color-text-muted); }
.breadcrumb a:hover { color: var(--color-accent); }
.breadcrumb [aria-current="page"] { color: var(--color-text); }

.lesson-header {
    margin-bottom: 2rem;
}
.lesson-number {
    display: inline-block;
    padding: 3px 12px;
    background: var(--color-bg-secondary);
    border-radius: var(--radius-full);
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--color-text-muted);
    margin-bottom: 0.75rem;
}
.lesson-title {
    font-size: clamp(1.6rem, 4vw, 2.25rem);
    font-weight: 700;
    line-height: 1.2;
    letter-spacing: -0.02em;
    margin-bottom: 0.75rem;
}
.lesson-date {
    display: block;
    font-size: 0.85rem;
    color: var(--color-text-muted);
}
.lesson-thumbnail {
    border-radius: var(--radius-md);
    overflow: hidden;
    margin-bottom: 2.5rem;
}
.lesson-thumbnail img {
    width: 100%;
    aspect-ratio: 16/9;
    object-fit: cover;
}
.lesson-content { margin-bottom: 3rem; }

.lesson-navigation {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: 16px;
    align-items: center;
    padding-top: 2rem;
    margin-top: 2rem;
    border-top: 1px solid var(--color-border);
}
.lesson-nav-link {
    display: flex;
    flex-direction: column;
    gap: 4px;
    color: var(--color-text);
    text-decoration: none;
    padding: 12px;
    border-radius: var(--radius-md);
    transition: background var(--transition);
}
.lesson-nav-link:hover { background: var(--color-bg-secondary); color: var(--color-text); }
.lesson-nav-link--next { text-align: right; }
.lesson-nav-label {
    font-size: 0.75rem;
    color: var(--color-text-muted);
    font-weight: 500;
}
.lesson-nav-title {
    font-size: 0.875rem;
    font-weight: 600;
}
.lesson-nav-back { text-align: center; }

/* ===== Footer ===== */
.site-footer {
    background: var(--color-bg-dark);
    color: #d1d5db;
    padding-block: 48px 32px;
}
.footer-inner {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 32px;
    margin-bottom: 32px;
}
.footer-lab-name {
    font-size: 1rem;
    font-weight: 700;
    color: #fff;
}
.footer-lab-name-en {
    font-size: 0.75rem;
    color: #9ca3af;
    margin-top: 4px;
    letter-spacing: 0.05em;
}
.footer-nav ul {
    display: flex;
    gap: 1.5rem;
    flex-wrap: wrap;
}
.footer-nav a {
    font-size: 0.875rem;
    color: #9ca3af;
    text-decoration: none;
    transition: color var(--transition);
}
.footer-nav a:hover { color: #fff; }
.footer-copyright {
    font-size: 0.75rem;
    color: #6b7280;
    padding-top: 1.5rem;
    border-top: 1px solid #2d2d2d;
}

/* ===== No posts ===== */
.no-posts {
    text-align: center;
    padding: 60px 24px;
    color: var(--color-text-muted);
}

/* ===== Class Materials Link Banner (トップページ) ===== */
.class-materials-banner {
    padding-block: 24px;
    background: var(--color-bg-secondary);
}
.class-materials-link-banner {
    display: block;
    text-decoration: none;
    color: inherit;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-bg);
    transition: box-shadow var(--transition), border-color var(--transition), transform var(--transition);
}
.class-materials-link-banner:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--color-accent);
    transform: translateY(-1px);
    color: inherit;
}
.class-materials-link-banner-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px;
    gap: 16px;
}
.class-materials-link-banner-label {
    font-size: 1rem;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 4px;
}
.class-materials-link-banner-desc {
    font-size: 0.875rem;
    color: var(--color-text-muted);
}
.class-materials-link-banner-arrow {
    font-size: 1.5rem;
    color: var(--color-accent);
    flex-shrink: 0;
    transition: transform var(--transition);
}
.class-materials-link-banner:hover .class-materials-link-banner-arrow {
    transform: translateX(4px);
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
    .posts-grid--4col { grid-template-columns: repeat(2, 1fr); }
    .course-grid { grid-template-columns: repeat(2, 1fr); }
    .archive-layout {
        grid-template-columns: 200px 1fr;
        gap: 32px;
    }
}

@media (max-width: 768px) {
    .menu-toggle { display: flex; }

    .main-nav {
        position: absolute;
        top: var(--header-height);
        left: 0;
        right: 0;
        background: rgba(255,255,255,0.98);
        backdrop-filter: blur(8px);
        border-bottom: 1px solid var(--color-border);
        display: none;
        padding: 16px 24px;
        pointer-events: none;
    }
    .main-nav.is-open { display: block; }
    .main-nav .nav-list {
        flex-direction: column;
        align-items: flex-start;
        gap: 0;
        pointer-events: auto;
    }
    .main-nav .nav-list li {
        width: 100%;
    }
    .main-nav .nav-list a {
        display: block;
        padding: 12px 0;
        font-size: 1rem;
        border-bottom: 1px solid var(--color-border);
    }
    .main-nav .nav-list li:last-child a { border-bottom: none; }

    .billboard { min-height: 60vh; }
    .billboard-slide.is-active { min-height: 60vh; }
    .billboard--small .billboard-slide.is-active { min-height: 30vh; }
    .billboard-content { padding-block: 60px; }
    .billboard-nav { width: 38px; height: 38px; font-size: 1.4rem; }

    .posts-grid--4col,
    .posts-grid--3col,
    .posts-grid--projects { grid-template-columns: repeat(2, 1fr); }

    .project-card--row .project-card-link {
        grid-template-columns: 240px 1fr;
    }

    .archive-layout {
        grid-template-columns: 1fr;
    }
    .archive-sidebar {
        position: static;
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: 16px 24px;
    }

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

    .lesson-navigation {
        grid-template-columns: 1fr 1fr;
    }
    .lesson-nav-back {
        grid-column: 1 / -1;
        grid-row: 2;
        order: 3;
    }

    .footer-inner {
        flex-direction: column;
        gap: 20px;
    }
}

@media (max-width: 480px) {
    .posts-grid--4col,
    .posts-grid--3col,
    .posts-grid--projects { grid-template-columns: 1fr; }

    .project-card--row .project-card-link {
        grid-template-columns: 1fr;
        grid-template-rows: auto 1fr;
    }
    .project-card--row .project-card-thumbnail {
        aspect-ratio: 16/9;
    }
    .project-card--row .project-card-body {
        padding: 20px 16px;
    }
    .course-grid { grid-template-columns: 1fr; }
    .archive-sidebar { grid-template-columns: 1fr; }
    .password-gate-inner { padding: 28px 20px; }
    .class-materials-header {
        flex-direction: column;
        align-items: flex-start;
    }
    .lesson-navigation {
        grid-template-columns: 1fr;
    }
    .lesson-nav-link--next { text-align: left; }
    .lesson-nav-back { grid-column: auto; grid-row: auto; }
    .post-navigation { grid-template-columns: 1fr; }
}

/* ===== 研究室についてページ ===== */
.about-sections {
    margin-bottom: 56px;
}

.about-section {
    display: grid;
    gap: 20px;
    margin-bottom: 20px;
}
.about-section--cols-1 { grid-template-columns: 1fr; }
.about-section--cols-2 { grid-template-columns: repeat(2, 1fr); }
.about-section--cols-3 { grid-template-columns: repeat(3, 1fr); }
.about-section--cols-4 { grid-template-columns: repeat(4, 1fr); }
.about-section--cols-6 { grid-template-columns: repeat(6, 1fr); }
.about-section--cols-8 { grid-template-columns: repeat(8, 1fr); }

.about-item-figure {
    margin: 0;
    overflow: hidden;
    border-radius: var(--radius-md);
    background: var(--color-bg-secondary);
}

.about-item-figure img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.about-item-figure figcaption {
    padding: 8px 12px;
    font-size: 0.8rem;
    color: var(--color-text-muted);
    line-height: 1.4;
}

.about-item-text {
    font-size: 0.95rem;
    line-height: 1.85;
    color: var(--color-text);
}

.about-content {
    max-width: var(--narrow-width);
    margin-inline: auto;
}

.about-content h2 {
    font-size: 1.35rem;
    font-weight: 700;
    margin-top: 2.5em;
    margin-bottom: 0.75em;
}

.about-content h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-top: 2em;
    margin-bottom: 0.5em;
}

.about-content p {
    margin-bottom: 1.25em;
    line-height: 1.85;
}

.about-content ul,
.about-content ol {
    list-style: revert;
    padding-left: 1.5em;
    margin-bottom: 1.25em;
}

.about-content img {
    border-radius: var(--radius-md);
    margin-block: 1.5em;
}

@media (max-width: 768px) {
    .about-section--cols-3 { grid-template-columns: repeat(2, 1fr); }
    .about-section--cols-4 { grid-template-columns: repeat(2, 1fr); }
    .about-section--cols-6 { grid-template-columns: repeat(3, 1fr); }
    .about-section--cols-8 { grid-template-columns: repeat(4, 1fr); }
}

@media (max-width: 480px) {
    .about-section--cols-2 { grid-template-columns: 1fr; }
    .about-section--cols-3 { grid-template-columns: 1fr; }
    .about-section--cols-4 { grid-template-columns: repeat(2, 1fr); }
    .about-section--cols-6 { grid-template-columns: repeat(2, 1fr); }
    .about-section--cols-8 { grid-template-columns: repeat(2, 1fr); }
}