:root {
    --bg: #f3f4f6;
    --bar: #1f2937;
    --bar-text: #f9fafb;
    --accent: #2563eb;
}

* { box-sizing: border-box; }

html, body {
    margin: 0;
    padding: 0;
    background: var(--bg);
    color: #111827;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    -webkit-text-size-adjust: 100%;
}

.topbar {
    position: sticky;
    top: 0;
    z-index: 10;
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.6rem 1rem;
    padding-top: calc(0.6rem + env(safe-area-inset-top));
    background: var(--bar);
    color: var(--bar-text);
}

.topbar .brand {
    font-weight: 700;
    color: var(--bar-text);
    text-decoration: none;
}

.doc-title {
    font-weight: 600;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.page-indicator {
    margin-left: auto;
    font-variant-numeric: tabular-nums;
    opacity: 0.85;
}

main { max-width: 1100px; margin: 0 auto; padding: 1rem; }

.page-title { font-size: 1.4rem; }

.empty { color: #6b7280; }
.empty code { background: #e5e7eb; padding: 0.1rem 0.35rem; border-radius: 4px; }

.packet-list { list-style: none; margin: 0; padding: 0; }
.packet-list li { margin: 0.4rem 0; }
.packet-list a {
    display: block;
    padding: 0.9rem 1rem;
    background: #fff;
    border-radius: 10px;
    text-decoration: none;
    color: #111827;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.06);
}
.packet-list a:active { background: #eef2ff; }
.packet-title { font-weight: 600; }

/* Viewer: continuous vertical scroll of rasterized pages. */
.viewer {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.75rem;
    padding: 0.5rem 0;
}

.page {
    margin: 0;
    width: 100%;
    max-width: 1000px;
}

.page img {
    display: block;
    width: 100%;
    height: auto;
    background: #fff;
    border-radius: 4px;
    box-shadow: 0 1px 6px rgba(0, 0, 0, 0.12);
    /* Reserve vertical space before load to avoid scroll jumps (US-Letter ratio). */
    aspect-ratio: 8.5 / 11;
    object-fit: contain;
}