:root {
    --bg: #f9fafb;
    --text: #111827;
    --muted: #6b7280;
    --accent: #2563eb;
    --card-shadow: 0 6px 20px rgba(17, 24, 39, 0.06);
    --radius: 14px;
    --max-width: 980px;
    --label-width: 110px; /* consistent label column width in sidebar */
}

html, body {
    height: 100%;
    background: var(--bg);
    color: var(--text);
    font-family: 'Inter', system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* fixed navbar space so content is not hidden behind it */
body {
    padding-top: 72px;
}

/* Navbar */
nav.navbar {
    background: #fff;
    box-shadow: 0 1px 6px rgba(2, 6, 23, 0.05);
}

.navbar-brand {
    color: var(--accent);
    font-weight: 700;
    letter-spacing: -0.4px;
}

.nav-link {
    color: #111827 !important;
    font-weight: 500;
}

/* Page container */
main.container {
    max-width: var(--max-width);
    margin-top: 28px;
    margin-bottom: 56px;
}

/* Paper header */
.paper-header {
    text-align: left;
    margin-bottom: 22px;
}

.paper-title {
    font-size: clamp(1.5rem, 2.6vw, 2.1rem);
    font-weight: 700;
    line-height: 1.12;
    margin-bottom: 6px;
}

.paper-meta {
    color: var(--muted);
    font-size: 0.95rem;
}

/* Layout: main + sidebar */
.paper-body {
    display: block;
}

@media (min-width: 992px) {
    .paper-body {
        display: grid;
        grid-template-columns: 1fr 320px;
        gap: 28px;
        align-items: start;
    }
}

/* Content card */
.content-card {
    background: #fff;
    border-radius: var(--radius);
    box-shadow: var(--card-shadow);
    padding: 28px;
}

.paper-content {
    color: #222;
    line-height: 1.75;
    font-size: 1.02rem;
}

/* Sidebar (meta card) - FIXED ALIGNMENT */
.meta-card {
    position: relative;
    background: #fff;
    border-radius: var(--radius);
    box-shadow: var(--card-shadow);
    padding: 20px;
    height: fit-content;
}

/* Use grid inside the meta card for exact label/value alignment */
.meta-grid {
    display: grid;
    grid-template-columns: var(--label-width) 1fr;
    gap: 10px 12px;
    align-items: start;
    row-gap: 14px;
    width: 100%;
}

.meta-label {
    color: var(--muted);
    font-size: 0.89rem;
    text-align: left;
    align-self: center;
    padding-right: 6px;
    white-space: nowrap; /* keep labels tidy */
    overflow: hidden;
    text-overflow: ellipsis;
}

.meta-value {
    font-weight: 600;
    color: #111827;
    font-size: 0.95rem;
    word-break: break-word; /* allow wrapping for long values without breaking layout */
    text-align: left;
}

/* Tags row becomes full-width block (below grid) so tags wrap nicely */
.meta-tags {
    margin-top: 6px;
    grid-column: 1 / -1; /* spans both columns */
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    align-items: center;
}

.tag {
    display: inline-block;
    background: #f1f5f9;
    color: #0f172a;
    padding: 6px 12px;
    font-size: 0.875rem;
    border-radius: 999px;
    font-weight: 600;
}

/* Buttons row spanning full width */
.meta-actions {
    grid-column: 1 / -1;
    margin-top: 14px;
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    align-items: center;
}

.download-btn {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    background: var(--accent);
    color: #fff;
    border: none;
    padding: 10px 14px;
    border-radius: 10px;
    font-weight: 600;
    text-decoration: none;
}

.small-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 8px 12px;
    border-radius: 10px;
    border: 1px solid rgba(37, 99, 235, 0.12);
    background: #fff;
    color: var(--accent);
    font-weight: 600;
    text-decoration: none;
}

/* Make sidebar sticky on large screens for better UX while reading */
@media (min-width: 992px) {
    .meta-card {
        position: sticky;
        top: 92px; /* below fixed navbar */
    }
}

/* PDF embed */
.pdf-wrap {
    margin-top: 18px;
    border-radius: 10px;
    overflow: hidden;
    background: #fff;
    border: 1px solid #eef2ff;
}

.pdf-iframe {
    width: 100%;
    height: 560px;
    border: 0;
    display: block;
}

/* Breadcrumbs */
.breadcrumbs {
    color: var(--muted);
    font-size: 0.95rem;
    margin-bottom: 12px;
}

/* Footer */
footer {
    text-align: center;
    padding: 40px 0;
    color: #e5e7eb;
    background: #111827;
    margin-top: 40px;
}

/* small screens adjustments */
@media (max-width: 991px) {
    .content-card {
        padding: 20px;
    }

    .meta-card {
        margin-top: 18px;
    }

    .pdf-iframe {
        height: 420px;
    }

    :root {
        --label-width: 110px;
    }

    /* keep label width consistent */
}

/* subtle hover */
a:hover {
    text-decoration: none;
}