converse.js/sass/_chatbox.scss

#conversejs {
    .chatbox-navback {
        display: none;
    }
    .flyout {
        border-radius: var(--chatbox-border-radius);
        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 {
        flex-wrap: nowrap;
        color: #ffffff;
        font-size: 100%;
        margin: 0;
        padding: 0.5em;
        position: relative;

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

        .avatar {
            height: 36px;
            width: 36px;
            margin-right: 0.5em;
        }

        .chatbox-title {
            .chatroom-description {
                font-size: 80%;
            }
        }
        .chatbox-buttons {
            flex-direction: row-reverse;
            @include make-col-ready();
            @include make-col(3);
            padding: 0;
        }

        .user-custom-message {
            color: var(--chat-head-color-lighten-50-percent);
            font-size: 75%;
            overflow: hidden;
            text-overflow: ellipsis;
            white-space: nowrap;
            margin: 0;
            padding-top: 0.2em;
        }

        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);

        img {
            &.emoji {
                height: 1.2em;
                width: 1.2em;
                margin: 0 .05em 0 .1em;
                vertical-align: -0.1em;
            }
        }

        @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;
            background-color: var(--chat-head-color);
            box-shadow: 1px 3px 5px 3px rgba(0, 0, 0, 0.4);
            z-index: 1;
            overflow-y: 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;
            height: 100%;
            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 {
            height: 100%;
            font-size: var(--message-font-size);
            color: var(--text-color);
            overflow-y: auto;
            border: 0;
            background-color: #ffffff;
            line-height: 1.3em;

            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 {
                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: 0.5em;
                width: 100%;
                border: none;
                min-height: var(--chat-textarea-height);
                margin-bottom: -4px; // Not clear why this is necessar :(
                resize: none;
                &.spoiler {
                    height: 42px;
                }
                &.correcting {
                    background-color: var(--chat-correcting-color);
                }
            }

            .send-button {
                position: static;
                left: var(--send-button-margin);
                width: 100%;
                background-color: var(--chat-head-color);
                color: var(--inverse-link-color);
                font-size: 80%;
                height: var(--send-button-height);
                bottom: calc(-var(--send-button-height) - var(--send-button-margin));

            }
            .chat-toolbar {
                box-sizing: border-box;
                margin: 0;
                padding: 0.25em;
                display: block;
                border-top: 4px solid var(--chat-head-color);
                background-color: white;
                color: var(--chat-head-color);
                .fa, .fa:hover,
                .far, .far:hover,
                .fas, .fas:hover {
                    color: var(--chat-head-color);
                    font-size: var(--font-size-large);
                }
                .unencrypted a,
                .unencrypted {
                    color: var(--text-color);
                    .toolbar-menu {
                        a {
                            color: var(--link-color);
                        }
                    }
                }
                .unverified a,
                .unverified {
                    color: #cf5300;
                }
                .private a,
                .private {
                    color: #4b7003;
                }
                .toggle-occupants {
                    float: right;
                }
                li {
                    cursor: pointer;
                    display: inline-block;
                    list-style: none;
                    padding: 0 0.5em;
                    &:hover {
                        cursor: pointer;
                    }
                    .toolbar-menu {
                        background-color: #fff;
                        bottom: 2rem;
                        box-shadow: -1px -1px 2px 0 rgba(0, 0, 0, 0.4);
                        height: auto;
                        margin-bottom: 0;
                        min-width: 21rem;
                        position: absolute;
                        right: 0;
                        top: auto;
                        z-index: $zindex-dropdown;

                        &.otr-menu {
                            left: -6em;
                            min-width: 15rem;

                            &.show {
                                display: flex;
                                flex-direction: column;
                            }
                        }

                        a {
                            color: var(--link-color);
                        }
                        .emoji-picker-container {
                            background: white;
                        }
                        ul {
                            &.emoji-picker {
                                overflow-y: scroll;
                                overflow-x: hidden;
                                padding: 0.5em;
                            }
                            li {
                                margin-left: 0;
                                cursor: pointer;
                                list-style: none;
                                position: relative;
                                &.insert-emoji {
                                    padding: 0.2em;
                                    &.picked {
                                        background-color: var(--highlight-color);
                                    }
                                    &:hover {
                                        background-color: var(--highlight-color);
                                    }
                                    a {
                                        font-size: var(--font-size-huge);
                                        &:hover {
                                            color: #8f2831;
                                        }
                                    }
                                }
                            }
                        }
                    }
                    &.toggle-smiley {
                        a.toggle-smiley {
                            padding: 0;
                        }
                        .emoji-toolbar {
                            box-shadow: 0 -1px 1px 0 rgba(0, 0, 0, 0.4);
                            .emoji-category-picker {
                                padding-top: 0.5em;
                                ul {
                                    display: flex;
                                    flex-direction: row;
                                    justify-content: space-between;
                                }
                            }

                            .emoji-category-picker,
                            .emoji-skintone-picker {
                                li {
                                    padding: 0.25em;
                                    font-size: var(--font-size-huge);
                                    &:hover {
                                        background-color: var(--highlight-color);
                                    }
                                }
                            }
                        }
                    }
                    &.toggle-otr {
                        ul {
                            z-index: 99;
                            li {
                                &:hover {
                                    background-color: var(--highlight-color);
                                }
                                display: block;
                                padding: 7px;
                                a {
                                    display: block;
                                }
                            }
                        }
                    }
                }
            }
        }
        .dragresize {
            background: transparent;
            border: 0;
            margin: 0;
            position: absolute;
            top: 0;
            z-index: 20;
            &-top {
                cursor: n-resize;
                height: 5px;
                width: 100%;
            }
            &-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 {
    .chat-textarea {
        max-height: var(--fullpage-max-chat-textarea-height);
    }
}

#conversejs.converse-embedded,
#conversejs.converse-overlayed {
    .chat-head {
        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;
        }
        .chatbox-title {
            @include make-col(8);
        }
        .chatbox-buttons {
            @include make-col(4);
        }
    }

    .emoji-picker {
        height: var(--embedded-emoji-picker-height);
    }
    
    .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);

            .chat-body {
                height: calc(100% - var(--overlayed-chat-head-height));
            }
        }
    }
}

#conversejs.converse-overlayed  {
    .flyout {
        bottom: var(--overlayed-chatbox-hover-height);
    }
    .box-flyout {
        height: var(--overlayed-chat-height);
        min-height: calc(var(--overlayed-chat-height) / 2);
    }
    .chat-head {
        height: var(--overlayed-chat-head-height);
    }
    .chat-textarea {
        max-height: var(--overlayed-max-chat-textarea-height);
    }
    .emoji-picker {
        height: var(--overlayed-emoji-picker-height);
    }
    .chatbox {
        .sendXMPPMessage {
            .chat-toolbar {
                li {
                    .toolbar-menu {
                        min-width: 235px;
                        ul {
                            &.emoji-toolbar {
                                width: 100%;
                                .emoji-category {
                                    float: left;
                                }
                            }
                        }
                    }
                    &.toggle-smiley {
                        .emoji-toolbar {
                            .emoji-category-picker {
                                ul {
                                    flex-wrap: wrap;
                                    justify-content: flex-start;
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

@include media-breakpoint-down(sm) {
	#conversejs.converse-overlayed {
		> .row {
			flex-direction: column;

            &.no-gutters {
                margin: -1em;
            }
		}
	}
}

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

#conversejs.converse-fullscreen  {
    .flyout {
        border-radius: 0;
        border-top: 0.8em solid var(--chat-head-color);
        border: var(--flyout-padding) solid var(--chat-head-color);
        bottom: 0;
    }
    .chatbox-btn {
        font-size: var(--fullpage-chatbox-button-size);
        margin: 0 0.3em;
    }
    .chat-head {
        height: var(--fullpage-chat-head-height);
        font-size: var(--font-size-huge);
        padding: 0;
        .user-custom-message {
            font-size: 70%;
            height: auto;
            line-height: var(--line-height);
        }
        .chatbox-title {
            @include make-col(10);
        }
        .chatbox-buttons {
            @include make-col(2);
        }
    }
    .chat-textarea {
        max-height: var(--fullpage-max-chat-textarea-height);
    }
    .emoji-picker {
        height: var(--fullpage-emoji-picker-height);
    }

    .chatbox {
        width: 100%;
        height: 100%;
        margin: 0;

        @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);
        }

        .box-flyout {
            background-color: var(--chat-head-color);
            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: calc(100% - var(--fullpage-chat-head-height));
            background-color: var(--chat-head-color);
            border-top-left-radius: var(--chatbox-border-radius);
            border-top-right-radius: var(--chatbox-border-radius);
        }
        .chat-content {
            border-top-left-radius: var(--chatbox-border-radius);
            border-top-right-radius: var(--chatbox-border-radius);
        }
        .chat-title {
            font-size: var(--font-size-huge);
            line-height: var(--line-height-huge);
        }
        .sendXMPPMessage {
            ul {
                width: 100%;
            }
            .toggle-smiley {
                ul {
                    &.emoji-toolbar {
                        .emoji-category-picker {
                            margin-right: 5em;
                        }
                        .emoji-category {
                            padding-left: 10px;
                            padding-right: 10px;
                        }
                    }
                }
            }
        }
    }
}

@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-embedded,
    #conversejs.converse-fullscreen {
        .chatbox {
            .box-flyout {
                .chatbox-navback {
                    display: flex;
                    @include make-col(2);
                    .fa-arrow-left {
                        &:before {
                            color: white;
                        }
                    }
                }
                .chatbox-title {
                    @include make-col(7);
                }
                .chatbox-buttons {
                    @include make-col(3);
                }
            }
        }
    }
}