riot-web/res/css/views/rooms/_Autocomplete.scss

.mx_Autocomplete {
    position: absolute;
    bottom: 0;
    z-index: 1001;
    width: 100%;
    border: 1px solid $primary-hairline-color;
    background: $primary-bg-color;
    border-bottom: none;
    border-radius: 4px 4px 0 0;
    max-height: 50vh;
    overflow: auto
}

.mx_Autocomplete_ProviderSection {
    border-bottom: 1px solid $primary-hairline-color;
}

.mx_Autocomplete_Completion_container_pill {
    margin: 12px;
    display: flex;
}

/* a "block" completion takes up a whole line */
.mx_Autocomplete_Completion_block {
    height: 34px;
    display: flex;
    padding: 0 12px;
    user-select: none;
    cursor: pointer;
    align-items: center;
    color: $primary-fg-color;
}

.mx_Autocomplete_Completion_block * {
     margin: 0 3px;
}

.mx_Autocomplete_Completion_pill {
    border-radius: 17px;
    height: 34px;
    padding: 0px 5px;
    display: flex;
    user-select: none;
    cursor: pointer;
    align-items: center;
    color: $primary-fg-color;
}

.mx_Autocomplete_Completion_pill > * {
    margin: 0 3px;
}

.mx_Autocomplete_Completion_container_truncate {
    .mx_Autocomplete_Completion_title,
    .mx_Autocomplete_Completion_subtitle,
    .mx_Autocomplete_Completion_description {
        /* Ellipsis for long names/subtitles/descriptions*/
        max-width: 150px;
        white-space: nowrap;
        overflow: hidden;
        text-overflow: ellipsis;
    }
}

/* container for pill-style completions */
.mx_Autocomplete_Completion_container_pill {
    margin: 12px;
    display: flex;
    flex-flow: wrap;
}

.mx_Autocomplete_Completion.selected {
    background: $menu-bg-color;
    outline: none;
}

.mx_Autocomplete_provider_name {
    margin: 12px;
    color: $primary-fg-color;
    font-weight: 400;
    opacity: 0.4;
}

/* styling for common completion elements */
.mx_Autocomplete_Completion_subtitle {
    font-style: italic;
    flex: 1;
}

.mx_Autocomplete_Completion_description {
    color: gray;
}