element-web/res/css/views/right_panel/_TimelineCard.scss

/*
Copyright 2021 - 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_TimelineCard {
    .mx_TimelineCard_timeline {
        overflow: hidden;
        position: relative; // offset parent for jump to bottom button
        flex: 1;
        border-radius: 8px;
    }

    .mx_NewRoomIntro {
        margin-inline-start: var(--BaseCard_EventTile-spacing-inline);
        margin-inline-end: var(--BaseCard_EventTile-spacing-inline);
    }

    .mx_EventTile_content {
        margin-right: 0;
    }

    .mx_EventTile {
        &[data-layout=irc],
        &[data-layout=group] {
            .mx_EventTile_avatar {
                position: absolute; // for IRC layout
                left: -3px;
            }

            .mx_EventTile_msgOption {
                margin-inline-end: 0;
            }

            .mx_DisambiguatedProfile,
            .mx_ReactionsRow,
            .mx_ThreadSummary {
                margin-inline-start: var(--BaseCard_EventTile-spacing-inline);
            }

            .mx_DisambiguatedProfile {
                max-width: calc(100% - var(--BaseCard_EventTile-spacing-inline)); // instead of $left-gutter
            }

            .mx_ReplyTile .mx_DisambiguatedProfile {
                margin-inline-start: 0;
                max-width: unset;
            }

            .mx_ReactionsRow {
                margin-inline-end: $spacing-8; // See: var(--ThreadView_group_spacing-end) for ReactionsRow on _EventTile.scss
            }

            .mx_ThreadSummary {
                margin-inline-end: 0;
                max-width: min(calc(100% - 36px), 600px);
            }
        }

        &[data-layout=bubble] {
            &::before {
                z-index: auto; // enable background color on hover
            }

            &.mx_EventTile_info .mx_MessageActionBar {
                inset-inline-end: calc($container-gap-width + var(--BaseCard_padding-inline) + 1px); // 1px: border width
            }

            .mx_ReactionsRow {
                position: relative; // display on hover
            }
        }

        &:not([data-layout="bubble"]) {
            &.mx_EventTile_info .mx_EventTile_line,
            .mx_EventTile_line {
                padding: var(--BaseCard_EventTile_line-padding-block) var(--BaseCard_EventTile-spacing-inline);
                padding-inline-end: $MessageTimestamp_width; // ensure timestamp is not hidden

                .mx_EventTile_e2eIcon {
                    inset-inline-start: 8px;
                }
            }

            .mx_MessageTimestamp {
                position: absolute; // for modern layout and IRC layout
                inset-inline-start: auto;
                inset-inline-end: 0;
            }

            &.mx_EventTile_info {
                .mx_EventTile_avatar {
                    left: 18px;
                }
            }
        }
    }

    .mx_EventTile,
    .mx_GenericEventListSummary {
        .mx_ThreadSummary {
            position: relative;
            padding-right: 11px;

            &::after {
                content: '';
                display: block;
                position: absolute;
                left: 0;
                bottom: -16px;
                height: 1px;
                width: 100%;
                border-bottom: 1px solid $message-action-bar-border-color;
            }
        }
    }

    .mx_CallEvent_wrapper {
        justify-content: center;
        margin: auto 5px;
        .mx_CallEvent {
            margin: 4px;
        }
    }

    .mx_GenericEventListSummary:not([data-layout=bubble]) {
        .mx_EventTile_line,
        > .mx_GenericEventListSummary_unstyledList > .mx_EventTile_info .mx_EventTile_avatar ~ .mx_EventTile_line {
            padding-inline-start: var(--BaseCard_EventTile-spacing-inline);
            padding-inline-end: var(--BaseCard_EventTile-spacing-inline);
        }
    }

    .mx_ReadReceiptGroup {
        top: -6px;
    }

    .mx_WhoIsTypingTile {
        margin-left: -12px; // undo padding on the message list
    }

    .mx_WhoIsTypingTile_avatars {
        flex-basis: 48px; // 12 (padding on message list) + 36 (padding on event lines)
    }

    .mx_GenericEventListSummary_unstyledList, // RR next to a message on the event list summary
    .mx_RoomView_MessageList {                // RR next to a message on the messsge list
        .mx_EventTile[data-layout=bubble] {
            .mx_ReadReceiptGroup {
                // 6px: scroll bar width (magic number)
                inset-inline-end: calc(-1 * var(--ReadReceiptGroup_EventBubbleTile-spacing-end) + $container-gap-width + 6px);
            }

            &.mx_EventTile_info {
                .mx_ReadReceiptGroup {
                    inset-inline-end: -4px; // align with RR outside of info tile
                }
            }
        }
    }
}