:root {
    --bg: #fff;
    --bg-secondary: #f8f8f8;
    --text: #282828;
    --text-secondary: #666;
    --text-tertiary: #999;
    --border: #e5e5e5;
    --accent: #0e6ee4;
    --accent-hover: #0b5bbf;
    --tab-active-bg: #282828;
    --tab-active-text: #fff;
    --tab-inactive-bg: transparent;
    --tab-inactive-text: #666;
    --score-bg: #e8f4e8;
    --score-text: #2d6e2d;
    --category-bg: #f0f0f0;
    --category-text: #555;
    --shadow: 0 1px 3px rgba(0,0,0,0.06);
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #1a1a1a;
        --bg-secondary: #242424;
        --text: #e8e8e8;
        --text-secondary: #aaa;
        --text-tertiary: #777;
        --border: #333;
        --accent: #6db3f2;
        --accent-hover: #8ec5f6;
        --tab-active-bg: #e8e8e8;
        --tab-active-text: #1a1a1a;
        --tab-inactive-bg: transparent;
        --tab-inactive-text: #888;
        --score-bg: #1e3a1e;
        --score-text: #7cc77c;
        --category-bg: #2a2a2a;
        --category-text: #aaa;
        --shadow: 0 1px 3px rgba(0,0,0,0.3);
    }
}

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

body {
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
}

#wrapper {
    max-width: 720px;
    margin: 0 auto;
    padding: 0 1.25rem 3rem;
}

/* Header */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 0 1rem;
    border-bottom: 1px solid var(--border);
    margin-bottom: 0.5rem;
}

.site-title {
    font-size: 1.1rem;
    font-weight: 600;
    letter-spacing: -0.01em;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    position: relative;
}

.nav-arrow {
    background: none;
    border: 1px solid var(--border);
    color: var(--text);
    cursor: pointer;
    padding: 0.3rem 0.6rem;
    border-radius: 6px;
    font-size: 0.85rem;
    transition: background 0.15s, border-color 0.15s;
}

.nav-arrow:hover {
    background: var(--bg-secondary);
    border-color: var(--text-tertiary);
}

.nav-arrow:disabled {
    opacity: 0.3;
    cursor: default;
}

.date-display {
    background: none;
    border: 1px solid var(--border);
    color: var(--text);
    cursor: pointer;
    padding: 0.3rem 0.75rem;
    border-radius: 6px;
    font-size: 0.85rem;
    font-family: inherit;
    transition: background 0.15s;
}

.date-display:hover {
    background: var(--bg-secondary);
}

.date-picker-hidden {
    position: absolute;
    right: 0;
    top: 100%;
    opacity: 0;
    pointer-events: none;
    width: 0;
    height: 0;
}

/* Tabs */
.tab-bar {
    display: flex;
    gap: 0.5rem;
    padding: 1rem 0 0.75rem;
    border-bottom: 1px solid var(--border);
    margin-bottom: 1.5rem;
}

.tab {
    background: var(--tab-inactive-bg);
    color: var(--tab-inactive-text);
    border: none;
    cursor: pointer;
    padding: 0.4rem 1rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-family: inherit;
    font-weight: 500;
    transition: all 0.15s;
}

.tab:hover {
    color: var(--text);
}

.tab.active {
    background: var(--tab-active-bg);
    color: var(--tab-active-text);
}

/* Content */
.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

main section {
    margin-bottom: 2.5rem;
}

main section h2 {
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

/* Paper list */
.paper-list, .tweet-list {
    list-style: none;
}

.paper-item {
    padding: 1rem 0;
    border-bottom: 1px solid var(--border);
}

.paper-item:last-child {
    border-bottom: none;
}

.paper-title {
    font-weight: 600;
    line-height: 1.35;
    margin-bottom: 0.3rem;
}

.paper-title a {
    color: var(--text);
    text-decoration: none;
    transition: color 0.15s;
}

.paper-title a:hover {
    color: var(--accent);
}

.paper-meta {
    font-size: 0.82rem;
    color: var(--text-secondary);
    line-height: 1.5;
    margin-bottom: 0.4rem;
}

.paper-meta .author-highlight {
    font-weight: 600;
    color: var(--text);
}

.paper-badges {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
    margin-bottom: 0.4rem;
}

.badge {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 500;
    padding: 0.15rem 0.5rem;
    border-radius: 10px;
}

.badge-score {
    background: var(--score-bg);
    color: var(--score-text);
}

.badge-category {
    background: var(--category-bg);
    color: var(--category-text);
}

.paper-reason {
    font-size: 0.82rem;
    color: var(--text-secondary);
    font-style: italic;
    margin-bottom: 0.3rem;
}

.paper-abstract {
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.55;
}

.paper-abstract summary {
    cursor: pointer;
    color: var(--text-tertiary);
    font-size: 0.78rem;
    margin-top: 0.2rem;
}

.paper-abstract summary:hover {
    color: var(--text-secondary);
}

.paper-abstract p {
    margin-top: 0.4rem;
}

.paper-links {
    margin-top: 0.4rem;
    font-size: 0.78rem;
}

.paper-links a {
    color: var(--accent);
    text-decoration: none;
    margin-right: 0.75rem;
}

.paper-links a:hover {
    text-decoration: underline;
}

/* Tweet list */
.tweet-item {
    padding: 0.9rem 0;
    border-bottom: 1px solid var(--border);
}

.tweet-item:last-child {
    border-bottom: none;
}

/* Twitter embeds */
.tweet-embed-target {
    display: flex;
    justify-content: center;
    margin-top: 0.5rem;
}

.tweet-embed-target .twitter-tweet {
    margin: 0 !important;
}

.tweet-embed-target .twitter-tweet iframe {
    max-width: 100% !important;
}

.tweet-summary {
    line-height: 1.5;
    margin-bottom: 0.3rem;
}

.tweet-meta {
    font-size: 0.78rem;
    color: var(--text-tertiary);
}

.tweet-meta a {
    color: var(--accent);
    text-decoration: none;
}

.tweet-meta a:hover {
    text-decoration: underline;
}

/* News grid */
.news-grid {
    display: flex;
    flex-direction: column;
    gap: 0;
}

.news-card {
    padding: 1.1rem 0;
    border-bottom: 1px solid var(--border);
}

.news-card:last-child {
    border-bottom: none;
}

.news-card-header {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    margin-bottom: 0.5rem;
}

.news-card-header img {
    width: 28px;
    height: 28px;
    border-radius: 6px;
    flex-shrink: 0;
}

.news-card-header a {
    font-weight: 600;
    font-size: 1rem;
    color: var(--text);
    text-decoration: none;
    transition: color 0.15s;
}

.news-card-header a:hover {
    color: var(--accent);
}

.news-card-articles {
    list-style: none;
    padding-left: 2.4rem;
}

.news-card-articles li {
    font-size: 0.82rem;
    color: var(--text-secondary);
    line-height: 1.55;
    padding: 0.1rem 0;
}

.news-card-articles li a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.15s;
}

.news-card-articles li a:hover {
    color: var(--accent);
}

/* Empty state */
.empty-state {
    color: var(--text-tertiary);
    font-size: 0.9rem;
    font-style: italic;
    padding: 2rem 0;
}

/* Loading */
.loading {
    text-align: center;
    padding: 3rem 0;
    color: var(--text-tertiary);
}

/* Footer */
footer {
    padding-top: 2rem;
    border-top: 1px solid var(--border);
    margin-top: 2rem;
    font-size: 0.75rem;
    color: var(--text-tertiary);
}

/* Responsive */
@media (max-width: 600px) {
    #wrapper {
        padding: 0 1rem 2rem;
    }

    header {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.75rem;
    }

    .header-right {
        align-self: stretch;
        justify-content: flex-start;
    }
}