/* Slim navigation bar, fixed to the top of the viewport.
   Hidden while the full-screen header (which has the big menu buttons) is on
   screen; slides in once the visitor scrolls past it, on every screen size. */

html {
    scroll-padding-top: 3.5em; /* native anchor jumps land below the bar */
}

#topnav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    height: 3.25em;
    background: rgba(15, 20, 50, 0.94);   /* same overlay as the header (#header::after) */
    -webkit-backdrop-filter: blur(8px);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid rgba(213, 218, 244, 0.25);
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.25);
    transform: translateY(-100%);
    transition: transform 0.3s ease;
    padding-top: env(safe-area-inset-top);  /* iPhone notch */
}

body.nav-visible #topnav {
    transform: translateY(0);
}

#topnav .inner {
    max-width: 60em;
    height: 100%;
    margin: 0 auto;
    padding: 0 1.25em;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1em;
}

#topnav .brand {
    display: flex;
    align-items: center;
    gap: 0.6em;
    font-weight: 700;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: #ffffff !important;
    text-decoration: none;
    border: 0;
    white-space: nowrap;
}

#topnav .brand:hover {
    color: #ffffff !important;          /* keep the wordmark colour on hover as well */
}

#topnav .brand img {
    width: 2.1em;   /* small version of the header logo */
    height: 2.1em;
    border-radius: 50%;
    display: block;
}

#topnav ul {
    list-style: none;
    display: flex;
    gap: 0.6em;
    margin: 0;
    padding: 0;
}

#topnav ul li {
    padding: 0;
    margin: 0;
}

#topnav ul a {
    display: block;
    padding: 0 1.1em;
    line-height: 2.2em;
    background-color: #2f3a80;          /* same as #header .actions .button */
    border: 1px solid #ffffff;          /* header buttons: 1px white inset outline */
    border-radius: 4px;
    color: #ffffff !important;          /* custom-colors.css forces all links blue with !important */
    font-size: 0.75em;
    font-weight: 400;
    letter-spacing: 0.125em;
    text-transform: uppercase;
    text-decoration: none;
    white-space: nowrap;
    transition: background-color 0.2s ease-in-out;
}

/* Like the header buttons: no colour change on hover, click or focus */
#topnav ul a:hover,
#topnav ul a:focus,
#topnav ul a:active {
    background-color: #2f3a80;
    /* main.css sets a:hover { border-bottom-color: transparent !important },
       which would erase the lower edge of the outline on hover */
    border-color: #ffffff !important;
    color: #ffffff !important;
}

/* Phones: drop the wordmark, spread the four links across the width */
@media screen and (max-width: 480px) {
    #topnav .brand {
        font-size: 0;      /* hide the wordmark text, keep the logo */
        gap: 0;
    }

    #topnav .brand img {
        width: 30px;
        height: 30px;
    }

    #topnav .inner {
        padding: 0 0.5em;
    }

    #topnav ul {
        flex: 1;
        justify-content: space-around;
    }

    #topnav ul {
        gap: 0.35em;
    }

    #topnav ul a {
        padding: 0 0.55em;
        line-height: 2.3em;
        font-size: 0.68em;
        letter-spacing: 0.08em;
    }
}