/* ===== RESET & BASE ===== */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --gap: 0.25rem;
}

html, body {
    height: 100%;
    overflow: hidden;
    font-family: "Helvetica", "Helvetica Neue", Arial, sans-serif;
    font-weight: 400;
    font-size: 13px;
    line-height: 1.4;
    color: #333;
    background: #fff;
}

a {
    color: inherit;
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

img {
    display: block;
}

/* ===== LAYOUT SHELL ===== */

#viewport {
    position: fixed;
    inset: 0;
    display: flex;
    align-items: flex-start;
}

#slideshow {
    flex-shrink: 0;
    height: 100%;
    position: relative;
}

#info {
    flex: 1;
    height: 100%;
    display: flex;
    align-items: flex-start;
    justify-content: flex-end;
    padding: 0.25rem var(--gap) 0 0;
    margin-left: var(--gap);
}

.info__content {
    display: grid;
    grid-template-columns: auto auto;
    row-gap: 0;
    white-space: nowrap;
}

.info__content a {
    display: contents;
}

.info__prefix {
    text-align: right;
}

.info__main {
    text-align: left;
}

.ghost {
    color: transparent;
    pointer-events: none;
    user-select: none;
}

.info__spacer {
    grid-column: 1 / -1;
    height: 1lh; /* one line-height */
}

/* ===== SLIDES ===== */
.slide {
    display: none;
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    align-items: flex-start;
}

.slide.active {
    display: flex;
}

/* ===== DUO LAYOUT (two 3:4 portraits) ===== */

.slide--duo {
    gap: var(--gap);
}

/*
 * Photo height is set by JS as --photo-h on #viewport.
 * This is calculated as: min(columnWidth * 4/3, viewportHeight * 0.95)
 * where columnWidth = (availableWidth - gap) / 2
 * and availableWidth is determined iteratively to account for
 * the actual space photos+info need.
 */

.slide--duo .slide__photo {
    height: var(--photo-h);
    overflow: visible;
    flex-shrink: 0;
}

.slide--duo .slide__photo img {
    height: 100%;
    width: auto;
}

/* ===== SOLO LAYOUT (one 4:3 landscape) ===== */

.slide--solo .slide__photo--wide {
    height: var(--photo-h);
    overflow: visible;
    flex-shrink: 0;
}

.slide--solo .slide__photo--wide img {
    height: 100%;
    width: auto;
}

/* ===== CAPTIONS ===== */
.slide__caption {
    text-align: right;
    margin-top: var(--gap);
    color: #666;
}

/* ===== NAVIGATION ZONES (click areas) ===== */

/* Duo: left photo = prev, right photo = next */
.slide--duo .slide__photo--left img {
    cursor: w-resize;
}

.slide--duo .slide__photo--right img {
    cursor: e-resize;
}

/* Solo: left half = prev, right half = next (handled in JS with overlay) */
.slide--solo .slide__photo--wide {
    position: relative;
}

.nav-zone {
    position: absolute;
    top: 0;
    height: 100%;
    width: 50%;
    z-index: 2;
}

.nav-zone--prev {
    left: 0;
    cursor: w-resize;
}

.nav-zone--next {
    right: 0;
    cursor: e-resize;
}

/* ===== MOBILE (portrait orientation) ===== */

@media (orientation: portrait) {

    #viewport {
        flex-direction: column;
    }

    #slideshow {
        width: 100% !important; /* override JS inline width */
        height: auto;
        flex-shrink: 0;
    }

    #info {
        flex: 1;
        width: 100%;
        margin-left: 0;
        padding: 0 var(--gap) 4% 0;
        align-items: flex-end;   /* push content to bottom */
        justify-content: flex-end; /* push content to right */
    }

    .slide {
        position: relative;
        width: 100%;
        height: auto;
    }

    /* DUO mobile: full width, no side padding, gap between photos */
    .slide--duo {
        gap: var(--gap);
    }

    .slide--duo .slide__photo {
        height: auto;
        flex: 1;
        min-width: 0;
    }

    .slide--duo .slide__photo img {
        width: 100%;
        height: auto;
    }

    /* Both captions aligned right; only right photo has 0.25rem padding from edge */
    .slide--duo .slide__photo--left .slide__caption {
        text-align: right;
    }

    .slide--duo .slide__photo--right .slide__caption {
        padding-right: var(--gap);
    }

    /* SOLO mobile: full width, no padding */
    .slide--solo .slide__photo--wide {
        height: auto;
        width: 100%;
    }

    .slide--solo .slide__photo--wide img {
        width: 100%;
        height: auto;
    }

    .slide--solo .slide__caption {
        padding-right: var(--gap);
    }
}