zulip/static/styles/popovers.css

.popover {
    width: auto;
}

.popover-title {
    overflow-x: hidden;
    text-overflow: ellipsis;
    text-align: center;

    font-size: inherit;
    line-height: inherit;
}

.popover-title:empty {
    display: none;
}

.popover_info {
    text-align: center;
}

.popover hr {
    margin-top: 5px;
    margin-bottom: 5px;
}

.popover-left,
.popover-right {
    max-width: 200px;
}

.streams_popover .sp-container {
    background: white;
    cursor: pointer;
    border: none;
}

.sp-container {
    z-index: 100;
}

.streams_popover .sp-palette-container {
    border-right: none;
}

.streams_popover .colorpicker-container {
    display: inline-block;
    margin-right: 10px;
}

.streams_popover .popover_sub_unsub_button {
    margin-top: 0px;
    float: none;
}

ul.sender_info_popover i {
    display: inline-block;
    width: 14px;
    text-align: center;
    margin-right: 3px;
}

ul.actions_popover i {
    display: inline-block;
    width: 14px;
    text-align: center;
    margin-right: 3px;
}

.user_popover {
    top: 100px!important;
    margin: -14px;
}

.popover-avatar .popover-inner {
    width: 240px;
}

.popover-avatar {
    height: 240px;
    width: 240px;
    background-size: cover;
    background-position: center;
    position: relative;
}

.message-info-popover {
    padding: 0;
}

.message-info-popover .popover-title {
    padding: 0;
}

.user_popover {
    padding: 0;
}

.user_popover .popover-title {
    padding: 0;
}

@media (max-width: 768px) {
    .message-info-popover {
        display: flex !important;
        justify-content: center;
        align-items: center;

        /* these are to override JS embedded inline styles. */
        top: 0px !important;
        left: 0px !important;
        margin: 0 !important;
        width: 100vw;
        height: 100vh;

        background-color: rgba(0,0,0,0.7);
        border-radius: 0px;
        border: none;

        pointer-events: none;
    }

    .message-info-popover .popover-inner {
        background-color: #fff;
        pointer-events: all;
    }
}