/**
 * Research articles (/articles/)
 * Long-form reading layout, mobile first. Loaded only on article pages.
 */

/* ========================================
   Shells
   ======================================== */
.article-shell,
.article-list-shell {
    max-width: 720px;
    margin: 0 auto;
    padding-bottom: var(--spacing-2xl);
}

.article-list-shell {
    max-width: 960px;
}

.article-breadcrumb {
    flex-wrap: nowrap;
    overflow: hidden;
}

.article-breadcrumb .breadcrumb-item {
    white-space: nowrap;
}

.article-breadcrumb .breadcrumb-item.active {
    overflow: hidden;
    text-overflow: ellipsis;
    min-width: 0;
    color: var(--color-text-secondary);
}

/* ========================================
   Article header
   ======================================== */
.article-header {
    margin-bottom: var(--spacing-lg);
}

.article-title {
    font-size: clamp(1.5rem, 1.1rem + 2.2vw, 2.25rem);
    line-height: 1.35;
    letter-spacing: 0.01em;
    margin-bottom: var(--spacing-md);
}

.article-lead {
    font-size: var(--font-size-lg);
    line-height: 1.75;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-md);
}

.article-meta {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs) var(--spacing-md);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.article-meta i {
    color: var(--color-text-muted);
}

.article-hero {
    margin: 0 0 var(--spacing-xl);
}

.article-hero img {
    display: block;
    width: 100%;
    height: auto;
    border-radius: var(--radius-lg);
    background-color: var(--color-bg-muted);
}

/* ========================================
   Key takeaways
   ======================================== */
.article-takeaways {
    background-color: var(--color-bg-muted);
    border: 1px solid var(--color-primary-bg);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.article-takeaways-title {
    font-size: var(--font-size-lg);
    color: var(--color-primary-dark);
    margin-bottom: var(--spacing-sm);
}

.article-takeaways ul {
    margin: 0;
    padding-left: 1.25em;
}

.article-takeaways li {
    line-height: 1.75;
    margin-bottom: var(--spacing-xs);
}

.article-takeaways li:last-child {
    margin-bottom: 0;
}

/* ========================================
   Body typography
   ======================================== */
.article-body {
    font-size: 1.0625rem;
    line-height: 1.85;
    overflow-wrap: break-word;
}

.article-body > :first-child {
    margin-top: 0;
}

.article-body p {
    margin-bottom: 1.25em;
}

.article-body h2,
.article-body h3,
.article-body h4 {
    line-height: 1.45;
    scroll-margin-top: calc(var(--header-height) + var(--spacing-md));
}

.article-body h2 {
    font-size: 1.375rem;
    margin: 2.25em 0 0.75em;
    padding-left: 0.65em;
    border-left: 4px solid var(--color-primary);
}

.article-body h3 {
    font-size: 1.1875rem;
    margin: 1.75em 0 0.6em;
}

.article-body h4 {
    font-size: var(--font-size-base);
    margin: 1.5em 0 0.5em;
}

.article-body a {
    text-decoration: underline;
    text-decoration-color: var(--color-primary-light);
    text-underline-offset: 3px;
}

.article-body ul,
.article-body ol {
    padding-left: 1.5em;
    margin-bottom: 1.25em;
}

.article-body li {
    margin-bottom: 0.4em;
}

.article-body li > ul,
.article-body li > ol {
    margin-top: 0.4em;
    margin-bottom: 0;
}

.article-body img {
    max-width: 100%;
    height: auto;
}

.article-body hr {
    margin: 2.5em 0;
    border-color: var(--color-border);
    opacity: 1;
}

.article-body code {
    font-size: 0.875em;
    color: var(--color-primary-dark);
    background-color: var(--color-bg-muted);
    padding: 0.125em 0.375em;
    border-radius: var(--radius-sm);
    word-break: break-word;
}

.article-body blockquote {
    margin: 1.75em 0;
    padding: var(--spacing-md) var(--spacing-lg);
    border-left: 4px solid var(--color-primary-light);
    background-color: var(--color-bg-muted);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    color: var(--color-text-secondary);
}

.article-body blockquote > :last-child {
    margin-bottom: 0;
}

/* Figures */
.article-body figure {
    margin: 2em 0;
}

.article-body figure img {
    display: block;
    width: 100%;
    border-radius: var(--radius-md);
    border: 1px solid var(--color-border-light);
}

.article-body figcaption {
    margin-top: var(--spacing-sm);
    font-size: var(--font-size-sm);
    line-height: 1.6;
    color: var(--color-text-secondary);
    text-align: center;
}

/* Tables: always wrap in <div class="table-wrap"> so wide tables scroll sideways on phones */
.table-wrap {
    margin: 1.75em 0;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    background-color: var(--color-bg-white);
}

.table-wrap table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.875rem;
    line-height: 1.55;
}

.table-wrap caption {
    caption-side: top;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    color: var(--color-text-secondary);
    text-align: left;
}

.table-wrap th,
.table-wrap td {
    padding: 0.5rem 0.625rem;
    border-bottom: 1px solid var(--color-border-light);
    text-align: left;
    vertical-align: top;
}

/* Row labels are short; wrapping them ("第 1 / 天") reads badly */
.table-wrap td:first-child {
    white-space: nowrap;
}

.table-wrap th {
    white-space: nowrap;
    font-weight: var(--font-weight-semibold);
    background-color: var(--color-bg-muted);
    border-bottom-color: var(--color-border);
}

.table-wrap tbody tr:last-child td {
    border-bottom: 0;
}

.table-wrap {
    box-shadow: 0 1px 2px rgba(15, 23, 42, 0.04), 0 8px 24px rgba(15, 23, 42, 0.05);
}

.table-wrap th {
    background-color: color-mix(in srgb, var(--color-primary) 8%, var(--color-bg-white));
}

.table-wrap td:first-child {
    font-weight: var(--font-weight-semibold);
}

.table-wrap tbody tr:nth-child(even) td {
    background-color: color-mix(in srgb, var(--color-primary) 3%, var(--color-bg-white));
}

.table-wrap tbody tr:hover td {
    background-color: color-mix(in srgb, var(--color-primary) 6%, var(--color-bg-white));
}

.table-wrap .num {
    text-align: right;
    white-space: nowrap;
    font-variant-numeric: tabular-nums;
}

/* Callouts: <div class="callout"> (note) or <div class="callout callout-warning"> (limitations) */
.callout {
    margin: 1.75em 0;
    padding: var(--spacing-md) var(--spacing-lg);
    background-color: var(--color-bg-muted);
    border-left: 4px solid var(--color-primary);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    font-size: 0.9875rem;
    line-height: 1.75;
}

.callout-warning {
    background-color: var(--color-accent-bg);
    border-left-color: var(--color-accent);
}

.callout .callout-title {
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--spacing-xs);
}

.callout > :last-child {
    margin-bottom: 0;
}

/* ========================================
   FAQ, related links, disclaimer
   ======================================== */
.article-faq,
.article-related {
    margin-top: var(--spacing-2xl);
}

.article-faq h2,
.article-related-title {
    font-size: 1.375rem;
    margin-bottom: var(--spacing-md);
}

.article-faq-item {
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    background-color: var(--color-bg-white);
    margin-bottom: var(--spacing-sm);
}

.article-faq-item summary {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    font-weight: var(--font-weight-semibold);
    line-height: 1.6;
    cursor: pointer;
    list-style: none;
}

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

/* CSS chevron, so it doesn't depend on an icon font codepoint */
.article-faq-item summary::after {
    content: "";
    flex-shrink: 0;
    width: 0.5rem;
    height: 0.5rem;
    margin: 0.5em 0.25rem 0 0;
    border-right: 2px solid var(--color-text-muted);
    border-bottom: 2px solid var(--color-text-muted);
    transform: rotate(45deg);
    transition: transform var(--transition-base);
}

.article-faq-item[open] summary::after {
    transform: rotate(-135deg);
    margin-top: 0.75em;
}

.article-faq-item p {
    margin: 0;
    padding: 0 var(--spacing-md) var(--spacing-md);
    line-height: 1.8;
    color: var(--color-text-secondary);
}

.article-related {
    padding: var(--spacing-lg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    background-color: var(--color-bg-white);
}

.article-related-title {
    font-size: var(--font-size-lg);
}

.article-related ul {
    margin: 0;
    padding-left: 1.25em;
}

.article-related li {
    margin-bottom: var(--spacing-sm);
    line-height: 1.6;
}

.article-related li:last-child {
    margin-bottom: 0;
}

.article-disclaimer {
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--color-border);
    font-size: var(--font-size-sm);
    line-height: 1.7;
    color: var(--color-text-muted);
}

/* ========================================
   List page
   ======================================== */
.article-list-header {
    margin-bottom: var(--spacing-xl);
}

.article-list-title {
    font-size: clamp(1.75rem, 1.4rem + 1.6vw, 2.25rem);
    margin-bottom: var(--spacing-sm);
}

.article-list-intro {
    color: var(--color-text-secondary);
    line-height: 1.75;
    max-width: 720px;
}

.article-cards {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
}

@media (min-width: 768px) {
    .article-cards {
        grid-template-columns: repeat(2, 1fr);
    }
}

.article-card {
    background-color: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-card);
    overflow: hidden;
    transition: box-shadow var(--transition-base), transform var(--transition-base);
}

.article-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.article-card-link {
    display: block;
    height: 100%;
    color: inherit;
}

.article-card-link:hover {
    color: inherit;
}

.article-card-thumb {
    aspect-ratio: 16 / 9;
    background-color: var(--color-bg-muted);
}

.article-card-thumb img {
    display: block;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.article-card-body {
    padding: var(--spacing-md) var(--spacing-lg) var(--spacing-lg);
}

.article-card-date {
    display: block;
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-xs);
}

.article-card-title {
    font-size: var(--font-size-xl);
    line-height: 1.45;
    margin-bottom: var(--spacing-sm);
}

.article-card-link:hover .article-card-title {
    color: var(--color-primary);
}

.article-card-lead {
    margin: 0;
    font-size: 0.9375rem;
    line-height: 1.7;
    color: var(--color-text-secondary);
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

/* ========================================
   Desktop refinements
   ======================================== */
@media (min-width: 768px) {
    .article-body {
        font-size: 1.125rem;
    }

    .article-body h2 {
        font-size: 1.5rem;
    }

    .article-body h3 {
        font-size: 1.25rem;
    }

    .table-wrap table {
        font-size: 0.9375rem;
    }

    .table-wrap th,
    .table-wrap td {
        padding: 0.625rem 0.875rem;
    }
}