converse.js/sass/_chatbox.scss

#conversejs {
    .chatbox-navback {
        display: none;
    }
    .flyout {
        position: absolute;

        @media screen and (max-height: $mobile-landscape-height) {
            border-radius: 0;
        }
        @media screen and (max-width: $mobile-portrait-length) {
            border-radius: 0;
        }

        @media screen and (max-height: $mobile-landscape-height) {
            bottom: 0;
        }
        @media screen and (max-width: $mobile-portrait-length) {
            bottom: 0;
        }
    }

    .chatbox-btn {
        border-radius: 25%;
        border: none;
        cursor: pointer;
        font-size: var(--chatbox-button-size);
        margin: 0 0.2em;
        padding: 0 0 0 0.5em;
        text-decoration: none;

        &:active {
            position: relative;
            top: 1px;
        }
    }

    .chat-head {
        display: flex;
        flex-direction: row;
        color: #ffffff;
        font-size: 100%;
        margin: 0;
        padding: 0;
        position: relative;

        &.chat-head-chatbox {
            background-color: var(--chat-head-color);
        }

        .avatar {
            margin-right: 0.5em;
        }

        .chat-head__desc {
            color: var(--chat-head-color-lighten-50-percent);
            font-size: var(--font-size-small);
            margin: 0;
            overflow: hidden;
            padding: 0.5rem 1rem 0.5rem 1rem;
            text-overflow: ellipsis;
            width: 100%;
            max-height: 5em;
        }

        .chatbox-title {
            padding: 0.75rem 1rem 0 1rem;
            display: flex;
            flex-direction: row;
            justify-content: space-between;
            width: 100%;
        }

        .chatbox-title--no-desc {
            padding: 0.75rem 1rem;
        }

        .chatbox-title--row {
            display: flex;
            flex-direction: row;
            overflow: hidden;
        }

        .chatbox-title__text {
            overflow: hidden;
            text-overflow: ellipsis;
        }

        .chatbox-title__buttons {
            display: flex;
            flex-direction: row-reverse;
            flex-wrap: nowrap;
            padding: 0;
        }

        a, a:visited, a:hover, a:not([href]):not([tabindex]) {
            &.chatbox-btn {
                &.fa,
                &.fas,
                &.far {
                    color: white;
                    &.button-on:before {
                        padding: 0.2em;
                        background-color: var(--chat-head-text-color);
                        color: var(--chat-head-color);
                    }
                }
            }
        }

        .chatbox-btn {
            color: white;
            &.fa, &.far, &.fas  {
                color: white;
            }
            &:active {
                position: relative;
                top: 1px;
            }
            &.button-on:before {
                border-radius: 5%;
                background-color: var(--chat-head-text-color);
                color: var(--chat-head-color);
            }
        }
    }

    .chatbox {
        text-align: left;
        margin: 0 var(--chat-gutter);

        @media screen and (max-height: $mobile-landscape-height) {
            margin: 0;
            width: var(--mobile-chat-width);
        }
        @media screen and (max-width: $mobile-portrait-length) {
            margin: 0;
            width: var(--mobile-chat-width);
        }

        .box-flyout {
            display: flex;
            flex-direction: column;
            justify-content: space-between;
            box-shadow: 1px 3px 5px 3px rgba(0, 0, 0, 0.4);
            z-index: 2;
            overflow: hidden;
            width: 100%;

            @media screen and (max-height: $mobile-landscape-height) {
                height: var(--mobile-chat-height);
                width: var(--mobile-chat-width);
                height: 100vh;
            }
            @media screen and (max-width: $mobile-portrait-length) {
                height: var(--mobile-chat-height);
                width: var(--mobile-chat-width);
                height: 100vh;
            }
        }
        .chat-title {
            display: var(--heading-display);
            font-family: var(--heading-font);
            color: var(--heading-color);
            display: block;
            line-height: var(--line-height-large);
            overflow: hidden;
            text-overflow: ellipsis;
            white-space: nowrap;
            &.groupchat {
                padding-right: var(--chatroom-head-title-padding-right);
            }
            a {
                color: var(--chat-head-text-color);
                width: 100%;
            }
        }
        .chat-body {
            display: flex;
            flex-direction: column;
            justify-content: space-between;
            background-color: var(--chat-head-color);
            border-bottom-left-radius: var(--chatbox-border-radius);
            border-bottom-right-radius: var(--chatbox-border-radius);

            @media screen and (max-height: $mobile-landscape-height) {
                border-bottom-left-radius: 0;
                border-bottom-right-radius: 0;
            }
            @media screen and (max-width: $mobile-portrait-length) {
                border-bottom-left-radius: 0;
                border-bottom-right-radius: 0;
            }
            border-top: 0;
            p {
                color: var(--text-color);
                font-size: var(--message-font-size);
                margin: 0;
                padding: 5px;
            }
        }
        .new-msgs-indicator {
            position: relative;
            width: 100%;
            cursor: pointer;
            background-color: var(--chat-head-color);
            color: var(--light-background-color);
            padding: 0.5em;
            font-size: 0.9em;
            text-align: center;
            z-index: 20;
            white-space: nowrap;
            margin-bottom: 0.25em;
        }
        .chat-content {
            background-color: var(--chat-content-background-color);
            border: 0;
            color: var(--text-color);
            font-size: var(--message-font-size);
            height: 100%;
            line-height: 1.3em;
            overflow: hidden;
            padding: 0;
            display: flex;
            flex-direction: column;
            justify-content: space-between;

            converse-chat-content {
                display: flex;
                flex-direction: column;
                height: 100%;
                justify-content: space-between;
            }

            converse-chat-message {
                .spinner {
                    width: 100%;
                    overflow-y: hidden;
                }
            }

            .chat-content__help {
                converse-chat-help {
                    border-top: 1px solid var(--chat-head-color);
                    display: block;
                    padding: 0.5em 0;
                }
                .close-chat-help {
                    float: right;
                    padding-right: 1em;
                    cursor: pointer;
                    color: var(--chat-content-background-color);
                }
            }

            .chat-content__messages {
                overflow-x: hidden;
                overflow-y: auto;
                height: 100%;
            }

            .chat-content__notifications {
                height: 1.7em;
                white-space: pre;
                background-color: var(--chat-content-background-color);
                color: var(--subdued-color);
                font-size: 90%;
                font-style: italic;
                line-height: var(--line-height-small);
                padding: 0 1em 0.3em;
                &:before {
                    content: " ";
                }
            }

            video {
                width: 100%
            }
            progress {
                margin: 0.5em 0;
                width: 100%
            }
        }

        .chat-content-sendbutton {
            height: calc(100% - (var(--chat-textarea-height) + var(--send-button-height) + 2 * var(--send-button-margin)));
        }

        .dropdown { /* status dropdown styles */
            background-color: var(--light-background-color);
            dd {
                margin: 0;
                padding: 0;
                position: relative;
            }
        }

        .sendXMPPMessage {
            -moz-background-clip: padding;
            -webkit-background-clip: padding-box;
            border-bottom-radius: var(--chatbox-border-radius);
            background-clip: padding-box;
            background-color: white;
            border: 0;
            margin: 0;
            padding: 0;
            @media screen and (max-height: $mobile-landscape-height) {
                width: 100%;
            }
            @media screen and (max-width: $mobile-portrait-length) {
                width: 100%;
            }

            .suggestion-box__results {
                &:after {
                    display: none;
                }
            }

            .spoiler-hint {
                width: 100%;
            }

            .chat-textarea, input {
                &:active, &:focus{
                    outline-color: var(--chat-head-color);
                }
                &.correcting {
                    background-color: var(--chat-correcting-color);
                }
            }

            .chat-textarea {
                color: var(--chat-textarea-color);
                background-color: var(--chat-textarea-background-color);
                border-top-left-radius: 0;
                border-top-right-radius: 0;
                border-bottom-radius: var(--chatbox-border-radius);
                padding-left: 0.5em;
                padding-right: 4.5em;
                padding-top: 0.5em;
                padding-bottom:0.5em;
                width: 100%;
                border: none;
                min-height: var(--chat-textarea-height);
                margin-bottom: -2px; // Not clear why this is necessar :(
                resize: none;
                &.spoiler {
                    height: 42px;
                }
            }
        }
        .dragresize {
            background: transparent;
            border: 0;
            margin: 0;
            position: absolute;
            top: 0;
            z-index: 20;
            &-top {
                cursor: n-resize;
                height: 5px;
                width: 100%;
            }
            &-left,
            &-occupants-left {
                cursor: w-resize;
                width: 5px;
                height: 100%;
                left: 0;
            }
            &-topleft {
                cursor: nw-resize;
                width: 15px;
                height: 15px;
                top: 0;
                left: 0;
            }
        }
    }
}

/* ******************* Overlay and embedded styles *************************** */

#conversejs.converse-embedded,
#conversejs.converse-overlayed {
    .controlbox-head {
        padding: 0.5em;
    }
    .chat-head {
        border-top-left-radius: 0;
        border-top-right-radius: 0;
    }
    .chatbox {
        min-width: var(--overlayed-chat-width) !important;
        width: var(--overlayed-chat-width);

        .box-flyout {
            min-width: var(--overlayed-chat-width) !important;
            width: var(--overlayed-chat-width);
        }
    }
}

#conversejs.converse-overlayed  {

    .chat-head, .box-flyout {
        border-top-left-radius: var(--chatbox-border-radius);
        border-top-right-radius: var(--chatbox-border-radius);
        @media screen and (max-height: $mobile-landscape-height) {
            border-top-left-radius: 0;
            border-top-right-radius: 0;
        }
        @media screen and (max-width: $mobile-portrait-length) {
            border-top-left-radius: 0;
            border-top-right-radius: 0;
        }
    }

    .flyout {
        bottom: var(--overlayed-chatbox-hover-height);
    }
    .box-flyout {
        height: var(--overlayed-chat-height);
        min-height: calc(var(--overlayed-chat-height) / 2);
    }
    .chat-head {
        min-height: var(--overlayed-chat-head-height);
    }
    .minimized-chats-flyout .chat-head {
        cursor: default;
    }
    .chat-textarea {
        max-height: var(--overlayed-max-chat-textarea-height);
    }
    .chatbox {
        .chat-body {
            height: calc(100% - var(--overlayed-chat-head-height));
        }
        .chatbox-title {
            cursor: pointer;
            padding: 0.5rem 0.75rem 0 0.75rem;
        }
        .chatbox-title--no-desc {
            padding: 0.5rem 0.75rem;
        }
        converse-dropdown {
            .btn--standalone {
                padding: 0 0 0 0.5em;
            }
        }
    }
}

@include media-breakpoint-down(sm) {
    #conversejs.converse-overlayed {
        > .row {
            flex-direction: column;
            &.no-gutters {
                margin: -1em;
            }
        }
    }
}


#conversejs.converse-embedded,
#conversejs.converse-fullscreen  {
    .flyout {
        border-radius: 0;
        border:none;
        bottom: 0;
    }

    .chatbox {
        margin: 0;
        .box-flyout {
            box-shadow: none;
            overflow: hidden;
        }
        @include make-col-ready();
        @include media-breakpoint-up(md) {
            @include make-col(8);
        }
        @include media-breakpoint-up(lg) {
            @include make-col(9);
        }
        @include media-breakpoint-up(xl) {
            @include make-col(10);
        }
    }

    &.converse-singleton {
        .flyout {
            border: none !important;
        }
        .chat-head {
            padding: 0.5em;
        }
        .chatbox {
            margin: 0;
            @include make-col-ready();
            @include media-breakpoint-up(md) {
                @include make-col(12);
            }
            @include media-breakpoint-up(lg) {
                @include make-col(12);
            }
            @include media-breakpoint-up(xl) {
                @include make-col(12);
            }
        }
    }
}

#conversejs.converse-embedded {
    .chat-head {
        font-size: var(--font-size-huge);
    }

    .converse-chatboxes {
        z-index: 1031; // One more than bootstrap navbar
        position: inherit;
        flex-wrap: nowrap;
        bottom: auto;
        height: 100%;
        width: 100%;
        margin-left: -15px;
    }

    .chatbox {
        .box-flyout {
            bottom: 0;
            height: 100%;
            min-width: auto;
            width: 100%;
        }
    }

    .chat-textarea {
        max-height: var(--fullpage-max-chat-textarea-height);
    }
}

/* ******************* Fullpage styles *************************** */

#conversejs.converse-fullscreen  {
    .chatbox-btn {
        font-size: var(--fullpage-chatbox-button-size);
        margin: 0 0.3em;
    }
    .chat-head {
        font-size: var(--font-size-huge);
    }
    .chat-textarea {
        max-height: var(--fullpage-max-chat-textarea-height);
    }
    .chatbox {
        .box-flyout {
            box-shadow: none;
            height: var(--fullpage-chat-height);
            min-height: calc(var(--fullpage-chat-height) / 2);
            width: var(--fullpage-chat-width);
            overflow: hidden;
        }
        .chat-body {
            height: inherit;
            overflow: hidden;
            background-color: var(--chat-head-color);
        }
        .chat-title {
            font-size: var(--font-size-huge);
            line-height: var(--line-height-huge);
        }
        .sendXMPPMessage {
            ul {
                width: 100%;
            }
        }
    }
}

@include media-breakpoint-down(sm) {
    #conversejs:not(.converse-embedded)  {
        > .row {
            flex-direction: row-reverse;
        }
        #converse-login-panel {
            .converse-form {
                padding: 3em 2em 3em;
            }
        }
        .chatbox {
            width: calc(100% - 50px);
            .row {
                .box-flyout {
                    left: 50px;
                    bottom: 0;
                    height: 100vh;
                    box-shadow: none;
                }
            }
        }
    }

    #conversejs.converse-mobile,
    #conversejs.converse-overlayed,
    #conversejs.converse-fullscreen {
        .chatbox {
            .box-flyout {
                .chatbox-navback {
                    display: flex;
                    padding-right: 1em;
                    .fa-arrow-left {
                        &:before {
                            color: white;
                        }
                    }
                }
            }
        }
    }
}