/**
 * ePub reader.
 *
 * Deliberately unopinionated: sizes and colours come from custom properties so a
 * theme can restyle the reader without overriding rules. Class names mirror
 * .advancedmedia-pdf so the two readers can be styled as a pair.
 */
.advancedmedia-epub {
    --advancedmedia-epub-height: 70vh;
    --advancedmedia-epub-min-height: 420px;
    --advancedmedia-epub-toc-width: 16rem;
    --advancedmedia-epub-border: 1px solid rgba(0, 0, 0, .18);
    --advancedmedia-epub-surface: #fff;

    margin-block: 1rem;
    min-width: 0;
    max-width: 100%;
}

.advancedmedia-epub-toolbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: .5rem;
    padding: .35rem .5rem;
    border: var(--advancedmedia-epub-border);
    border-bottom: 0;
}

.advancedmedia-epub-toolbar button {
    cursor: pointer;
    background: transparent;
    border: var(--advancedmedia-epub-border);
    border-radius: 3px;
    padding: .25rem .6rem;
    font: inherit;
    line-height: 1.4;
}

.advancedmedia-epub-pager {
    display: flex;
    gap: .25rem;
}

.advancedmedia-epub-pager button {
    min-width: 2.25rem;
    font-size: 1.15rem;
}

.advancedmedia-epub-body {
    display: flex;
    align-items: stretch;
    height: var(--advancedmedia-epub-height);
    min-height: var(--advancedmedia-epub-min-height);
    border: var(--advancedmedia-epub-border);
    background: var(--advancedmedia-epub-surface);
    /* See the note on .epub-container below: nothing in here may be allowed to
       widen an ancestor. */
    min-width: 0;
    max-width: 100%;
}

.advancedmedia-epub-toc {
    flex: 0 0 var(--advancedmedia-epub-toc-width);
    overflow-y: auto;
    border-right: var(--advancedmedia-epub-border);
    padding: .5rem;
}

.advancedmedia-epub-toc ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

.advancedmedia-epub-toc li + li {
    margin-top: .2rem;
}

/* Chapters nested under a part or unit heading. */
.advancedmedia-epub-toc ul ul {
    margin-top: .2rem;
    padding-left: .9rem;
}

.advancedmedia-epub-toc a,
.advancedmedia-epub-toc span {
    display: block;
    padding: .2rem .3rem;
    text-decoration: none;
    font-size: .9em;
}

/* Listed in the contents but not present in this file. */
.advancedmedia-epub-toc .advancedmedia-epub-toc-unavailable {
    opacity: .55;
}

.advancedmedia-epub-toc a:hover,
.advancedmedia-epub-toc a:focus {
    text-decoration: underline;
}

/* epub.js measures this element to paginate, so it must have a real size before
   the book is displayed — hence a flex child that fills, not an auto height.
   flex-basis 0 (not auto) so the book's own width never feeds back into the
   layout. */
.advancedmedia-epub-viewport {
    position: relative;
    flex: 1 1 0%;
    min-width: 0;
    max-width: 100%;
    overflow: hidden;
}

/* ⚠️ TAKE epub.js's CONTAINER OUT OF FLOW. DO NOT REMOVE.
 *
 * In paginated mode epub.js lays the whole section out as CSS multi-columns and
 * sizes its container to the FULL width of every column at once — measured here at
 * 294,084px for one book of Paradise Lost. In normal flow that width propagates
 * upward: flex and grid items default to min-width:auto, so the track cannot shrink
 * below its content, and the reader, the item column and the page itself stretch to
 * a quarter of a million pixels. The symptom is a blank reader beside a page that
 * scrolls sideways for ever, which looks nothing like a CSS bug.
 *
 * Absolute positioning ends it at this boundary: the container fills the viewport,
 * the viewport clips it, and its content size stops propagating. The !important is
 * required because epub.js writes width/height inline. */
.advancedmedia-epub-viewport > .epub-container {
    position: absolute !important;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    width: auto !important;
    height: auto !important;
}

.advancedmedia-epub-status {
    margin: .5rem 0;
    font-style: normal;
    opacity: .8;
}

/* The table of contents costs too much width on a phone; it opens over the text
   instead of beside it. */
@media (max-width: 600px) {
    .advancedmedia-epub {
        --advancedmedia-epub-toc-width: 100%;
    }

    .advancedmedia-epub-toc {
        border-right: 0;
        border-bottom: var(--advancedmedia-epub-border);
    }

    .advancedmedia-epub-body:has(.advancedmedia-epub-toc:not([hidden])) .advancedmedia-epub-viewport {
        display: none;
    }

    .advancedmedia-epub-body {
        flex-wrap: wrap;
    }
}

[hidden] {
    display: none !important;
}