element-web/res/css/views/rooms/_ThreadSummary.scss

/*
Copyright 2022 The Matrix.org Foundation C.I.C.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

.mx_ThreadSummary,
.mx_ThreadSummary_content,
.mx_ThreadSummary_icon {
    font-size: $font-12px;
}

.mx_ThreadSummary,
.mx_ThreadSummary_content {
    color: $secondary-content;
}

.mx_ThreadSummary,
.mx_ThreadSummary_icon {
    margin-top: $spacing-8;
}

.mx_ThreadSummary {
    min-width: 267px;
    max-width: min(calc(100% - var(--EventTile_group_line-spacing-inline-start)), 600px); // leave space on both left & right gutters
    width: fit-content;
    height: 40px;
    position: relative;
    background-color: $system;
    padding-inline: $spacing-12 $spacing-16;
    display: flex;
    align-items: center;
    justify-content: flex-start;
    border-radius: 8px;
    box-sizing: border-box;
    clear: both;
    overflow: hidden;
    border: 1px solid $system; // always render a border so the hover effect doesn't require a re-layout

    .mx_ThreadSummary_chevron {
        position: absolute;
        top: 0;
        right: 0;
        bottom: 0;
        width: 60px;
        box-sizing: border-box;
        // XXX: We use `$system-transparent` instead of `transparent` to work around a Safari <15.4 bug
        background: linear-gradient(270deg, $system 50%, $system-transparent 100%);

        opacity: 0;
        transform: translateX(60px);
        transition: all .1s ease-in-out;

        &::before {
            content: '';
            position: absolute;
            top: 50%;
            right: $spacing-12;
            transform: translateY(-50%);
            width: 12px;
            height: 12px;
            mask-image: url('$(res)/img/compound/chevron-right-12px.svg');
            mask-position: center;
            mask-size: contain;
            mask-repeat: no-repeat;
            background-color: $secondary-content;
        }
    }

    &:hover,
    &:focus {
        border-color: $quinary-content;

        .mx_ThreadSummary_chevron {
            opacity: 1;
            transform: translateX(0);
        }
    }

    &::before {
        @mixin ThreadSummaryIcon;
        align-self: center; // v-align the threads icon
    }

    .mx_ThreadSummary_sender,
    .mx_ThreadSummary_content,
    .mx_ThreadSummary_replies_amount {
        line-height: var(--EventTile_ThreadSummary-line-height);
    }

    .mx_ThreadSummary_sender,
    .mx_ThreadSummary_content {
        text-overflow: ellipsis;
        overflow: hidden;
        white-space: nowrap;
    }

    .mx_ThreadSummary_sender {
        font-weight: $font-semi-bold;
    }

    .mx_ThreadSummary_content {
        margin-left: $spacing-4;
        flex: 1;
    }

    .mx_ThreadSummary_replies_amount {
        @mixin ThreadRepliesAmount;
    }

    .mx_MessagePanel_narrow & {
        min-width: initial;
        max-width: 100%; // prevent overflow
        width: initial;
    }
}

.mx_ThreadSummary_avatar {
    margin-inline-end: $spacing-8;
}

.mx_ThreadSummary_icon {
    display: inline-block;
    margin-bottom: $spacing-8;

    &::before {
        @mixin ThreadSummaryIcon;
        vertical-align: middle;
        margin-inline-end: $spacing-8;
        margin-top: -2px;
    }

    a& {
        color: $secondary-content;
    }
}