zulip/static/styles/overlay.css

#overlay {
    position: fixed;
    top: 0px;
    left: 0px;

    width: 100vw;
    height: 100vh;

    pointer-events: none;
    opacity: 0;

    background-color: #19203a;
    box-shadow: 0 0 20px rgba(0,0,0,0.2);
    z-index: 101;

    transition: all 0.2s ease;

    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

#overlay.show {
    pointer-events: auto;
    opacity: 1;
}

#overlay .image-preview {
    position: relative;
    width: calc(100% - 20px);
    height: calc(100% - 65px - 30px);
    margin: 0px;

    background-color: #19203a;

    background-size: contain;
    background-repeat: no-repeat;
    background-position: center center;
}

#overlay .exit {
    float: right;

    color: rgba(255,255,255,0.8);
    font-size: 2rem;
    font-weight: 200;
    margin: 22px 20px;

    transform: scaleY(0.75);
    font-weight: 300;

    opacity: 0;
    pointer-events: none;
    cursor: pointer;
    transition: all 0.2s ease;
}

#overlay .exit {
    pointer-events: auto;
    opacity: 1;
}

#overlay .image-info-wrapper {
    background-color: transparent;
}

#overlay .image-description,
#overlay .image-actions {
    float: left;
    margin: 20px 20px;
}

#overlay .image-actions {
    float: right;
}

#overlay .image-actions a {
    margin-bottom: 0px;
    margin-top: 0px;
}

#overlay .image-actions .icon {
    font-size: 1.1rem;
    display: inline-block;
}

#overlay .image-actions .icon .text {
    font-size: 0.9rem;
}

#overlay .image-actions span:nth-of-type(2) {
    position: relative;
    top: 1px;
}

#overlay .image-actions .open span:nth-of-type(2) {
    top: 2px;
}

#overlay .image-description {
    /* approx width of screen minus action buttons on the side. */
    width: calc(100% - 320px);

    font-size: 1.3rem;
    color: #fff;
}

#overlay .image-description .title {
    font-weight: 500;
    line-height: normal;
    max-width: calc(100%);

    /* Required for text-overflow */
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

#overlay .image-description .user {
    font-weight: 300;
}

.image-actions .button {
    font-size: 0.8rem;
    min-width: inherit;
    padding: 4px 10px;
    border: 1px solid rgba(255,255,255,0.6);
    background-color: transparent;
    color: #fff;
    border-radius: 4px;
}

.image-actions .button:hover {
    background-color: #fff;
    color: #19203a;
}

.image-actions a.button {
    text-decoration: none;
}

.button .download {
    top: 1px;
}

#overlay .clear-float {
    clear: both;
}