/* ===========================================================
   Shared site header (2026-05-24)
   Flat Material — solid surfaces, no gradients, Material
   elevation shadows only. Sits at the top of every page.

   Split out of site.css so the GENERATED pages under /bingo/
   and /rba/ can wear the header without loading site.css:
   that stylesheet sets body{padding:20px; height:50vh;
   display:flex} for the legacy tool layout, plus global
   element rules, which would fight those pages' own CSS and
   break the contrast pairs their build asserts.

   Every colour is var(--token, literal). On a page that loads
   site.css the tokens win, so the header stays in step with
   the rest of the site; on a generated page the literal
   applies. One definition either way, no copy to drift.
   =========================================================== */
.site-header {
    background-color: var(--input-bg-color, #1e1e1e);
    color: var(--text-color, #e0e0e0);
    font-family: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
    padding: 12px 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    /* No assumption about the host page's body padding; site.css adds the
       negative margin back for the legacy pages that carry it. */
    margin: 0;
    flex-wrap: wrap;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.4); /* Material elevation 2dp */
    position: relative;
    z-index: 4;
}

.site-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--text-color, #e0e0e0);
    font-weight: 500;
    font-size: 1.05rem;
    text-decoration: none;
}

    .site-brand:hover {
        text-decoration: none;
        color: var(--text-color, #e0e0e0);
    }

.brand-mark {
    width: 24px;
    height: 24px;
    border-radius: 2px;
    background-color: var(--primary-color, #673AB7);
    flex-shrink: 0;
}

.brand-text {
    color: inherit;
}

.site-nav {
    display: flex;
    gap: 2px;
    flex-wrap: wrap;
}

    .site-nav a {
        color: var(--text-color, #e0e0e0);
        padding: 8px 16px;
        /* Set in caps, and caps need roughly 15% more letter height than mixed case to be
           recognised as readily (NN/g, glanceable reading). At 0.95rem these links were SMALLER
           than the body text they sit above, so the caps were costing legibility on the site's
           primary navigation rather than buying emphasis. */
        font-size: 1.05rem;
        font-weight: 500;
        text-decoration: none;
        text-transform: uppercase;
        letter-spacing: 0.04em;
        transition: background-color 0.15s ease;
        border-radius: 2px;
    }

        .site-nav a:hover {
            background-color: var(--hover-color, #333333);
            text-decoration: none;
            color: var(--text-color, #e0e0e0);
        }

        .site-nav a[aria-current="page"] {
            color: var(--secondary-color);
        }

@media (max-width: 640px) {
    .site-header {
        padding: 10px 14px;
        flex-direction: column;
        align-items: flex-start;
    }

    .site-nav a {
        padding: 6px 12px;
        font-size: 0.88rem;
    }
}