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

/*
Copyright 2020 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_RoomSublist {
    margin-left: 8px;
    margin-bottom: 4px;

    &.mx_RoomSublist_hidden {
        display: none;
    }

    .mx_RoomSublist_headerContainer {
        // Create a flexbox to make alignment easy
        display: flex;
        align-items: center;

        // ***************************
        // Sticky Headers Start

        // Ideally we'd be able to use `position: sticky; top: 0; bottom: 0;` on the
        // headerContainer, however due to our layout concerns we actually have to
        // calculate it manually so we can sticky things in the right places. We also
        // target the headerText instead of the container to reduce jumps when scrolling,
        // and to help hide the badges/other buttons that could appear on hover. This
        // all works by ensuring the header text has a fixed height when sticky so the
        // fixed height of the container can maintain the scroll position.

        // The combined height must be set in the LeftPanel component for sticky headers
        // to work correctly.
        padding-bottom: 8px;
        height: 24px;
        color: $roomlist-header-color;

        .mx_RoomSublist_stickable {
            flex: 1;
            max-width: 100%;

            // Create a flexbox to make ordering easy
            display: flex;
            align-items: center;

            // We use a generic sticky class for 2 reasons: to reduce style duplication and
            // to identify when a header is sticky. If we didn't have a consistent sticky class,
            // we'd have to do the "is sticky" checks again on click, as clicking the header
            // when sticky scrolls instead of collapses the list.
            &.mx_RoomSublist_headerContainer_sticky {
                position: fixed;
                height: 32px; // to match the header container
                // width set by JS
                width: calc(100% - 22px);
            }

            // We don't have a top style because the top is dependent on the room list header's
            // height, and is therefore calculated in JS.
            // The class, mx_RoomSublist_headerContainer_stickyTop, is applied though.
        }

        // Sticky Headers End
        // ***************************

        .mx_RoomSublist_badgeContainer {
            // Create another flexbox row because it's super easy to position the badge this way.
            display: flex;
            align-items: center;
            justify-content: center;

            // Apply the width and margin to the badge so the container doesn't occupy dead space
            .mx_NotificationBadge {
                // Do not set a width so the badges get properly sized
                margin-left: 8px; // same as menu+aux buttons
            }
        }

        &:not(.mx_RoomSublist_headerContainer_withAux) {
            .mx_NotificationBadge {
                margin-right: 4px; // just to push it over a bit, aligning it with the other elements
            }
        }

        .mx_RoomSublist_auxButton,
        .mx_RoomSublist_menuButton {
            margin-left: 8px; // should be the same as the notification badge
            position: relative;
            width: 24px;
            height: 24px;
            border-radius: 32px;

            &::before {
                content: '';
                width: 16px;
                height: 16px;
                position: absolute;
                top: 4px;
                left: 4px;
                mask-position: center;
                mask-size: contain;
                mask-repeat: no-repeat;
                background: $muted-fg-color;
            }
        }

        // Hide the menu button by default
        .mx_RoomSublist_menuButton {
            visibility: hidden;
            width: 0;
            margin: 0;
        }

        .mx_RoomSublist_auxButton::before {
            mask-image: url('$(res)/img/element-icons/roomlist/plus.svg');
        }

        .mx_RoomSublist_menuButton::before {
            mask-image: url('$(res)/img/element-icons/context-menu.svg');
        }

        .mx_RoomSublist_headerText {
            flex: 1;
            max-width: calc(100% - 16px); // 16px is the badge width
            line-height: $font-16px;
            font-size: $font-13px;
            font-weight: 600;

            // Ellipsize any text overflow
            text-overflow: ellipsis;
            overflow: hidden;
            white-space: nowrap;

            .mx_RoomSublist_collapseBtn {
                display: inline-block;
                position: relative;
                width: 14px;
                height: 14px;
                margin-right: 6px;

                &::before {
                    content: '';
                    width: 18px;
                    height: 18px;
                    position: absolute;
                    mask-position: center;
                    mask-size: contain;
                    mask-repeat: no-repeat;
                    background-color: $roomlist-header-color;
                    mask-image: url('$(res)/img/feather-customised/chevron-down.svg');
                }

                &.mx_RoomSublist_collapseBtn_collapsed::before {
                    transform: rotate(-90deg);
                }
            }
        }
    }

    // In the general case, we leave height of headers alone even if sticky, so
    // that the sublists below them do not jump. However, that leaves a gap
    // when scrolled to the top above the first sublist (whose header can only
    // ever stick to top), so we force height to 0 for only that first header.
    // See also https://github.com/vector-im/element-web/issues/14429.
    &:first-child .mx_RoomSublist_headerContainer {
        height: 0;
        padding-bottom: 4px;
    }

    .mx_RoomSublist_resizeBox {
        position: relative;

        // Create another flexbox column for the tiles
        display: flex;
        flex-direction: column;
        overflow: hidden;

        .mx_RoomSublist_tiles {
            flex: 1 0 0;
            overflow: hidden;
            // need this to be flex otherwise the overflow hidden from above
            // sometimes vertically centers the clipped list ... no idea why it would do this
            // as the box model should be top aligned. Happens in both FF and Chromium
            display: flex;
            flex-direction: column;

            mask-image: linear-gradient(0deg, transparent, black 4px);
        }

        .mx_RoomSublist_resizerHandles_showNButton {
            flex: 0 0 32px;
        }

        .mx_RoomSublist_resizerHandles {
            flex: 0 0 4px;
            display: flex;
            justify-content: center;
            width: 100%;
        }

        // Class name comes from the ResizableBox component
        // The hover state needs to use the whole sublist, not just the resizable box,
        // so that selector is below and one level higher.
        .mx_RoomSublist_resizerHandle {
            cursor: ns-resize;
            border-radius: 3px;

            // Override styles from library
            max-width: 64px;
            height: 4px !important; // Update RESIZE_HANDLE_HEIGHT if this changes

            // This is positioned directly below the 'show more' button.
            position: relative !important;
            bottom: 0 !important; // override from library
        }

        &:hover, &.mx_RoomSublist_hasMenuOpen {
            .mx_RoomSublist_resizerHandle {
                opacity: 0.8;
                background-color: $primary-fg-color;
            }
        }
    }

    .mx_RoomSublist_showNButton {
        cursor: pointer;
        font-size: $font-13px;
        line-height: $font-18px;
        color: $roomtile-preview-color;

        // Update the render() function for RoomSublist if these change
        // Update the ListLayout class for minVisibleTiles if these change.
        height: 24px;
        padding-bottom: 4px;

        // We create a flexbox to cheat at alignment
        display: flex;
        align-items: center;

        .mx_RoomSublist_showNButtonChevron {
            position: relative;
            width: 18px;
            height: 18px;
            margin-left: 12px;
            margin-right: 16px;
            mask-position: center;
            mask-size: contain;
            mask-repeat: no-repeat;
            background: $roomlist-header-color;
            left: -1px; // adjust for image position
        }

        .mx_RoomSublist_showMoreButtonChevron,
        .mx_RoomSublist_showLessButtonChevron {
            mask-image: url('$(res)/img/feather-customised/chevron-down.svg');
        }

        .mx_RoomSublist_showLessButtonChevron {
            transform: rotate(180deg);
        }
    }

    &.mx_RoomSublist_hasMenuOpen,
    &:not(.mx_RoomSublist_minimized) > .mx_RoomSublist_headerContainer:focus-within,
    &:not(.mx_RoomSublist_minimized) > .mx_RoomSublist_headerContainer:hover {
        .mx_RoomSublist_menuButton {
            visibility: visible;
            width: 24px;
            margin-left: 8px;
        }
    }

    &.mx_RoomSublist_minimized {
        .mx_RoomSublist_headerContainer {
            height: auto;
            flex-direction: column;
            position: relative;

            .mx_RoomSublist_badgeContainer {
                order: 0;
                align-self: flex-end;
                margin-right: 0;
            }

            .mx_RoomSublist_stickable {
                order: 1;
                max-width: 100%;
            }

            .mx_RoomSublist_auxButton {
                order: 2;
                visibility: visible;
                width: 32px !important; // !important to override hover styles
                height: 32px !important; // !important to override hover styles
                margin-left: 0 !important; // !important to override hover styles
                background-color: $roomlist-button-bg-color;
                margin-top: 8px;

                &::before {
                    top: 8px;
                    left: 8px;
                }
            }
        }

        .mx_RoomSublist_resizeBox {
            align-items: center;
        }

        .mx_RoomSublist_showNButton {
            flex-direction: column;

            .mx_RoomSublist_showNButtonChevron {
                margin-right: 12px; // to center
            }
        }

        .mx_RoomSublist_menuButton {
            height: 16px;
        }

        &.mx_RoomSublist_hasMenuOpen,
        & > .mx_RoomSublist_headerContainer:hover {
            .mx_RoomSublist_menuButton {
                visibility: visible;
                position: absolute;
                bottom: 48px; // align to middle of name, 40px for aux button (with padding) and 8px for alignment
                right: 0;
                width: 16px;
                height: 16px;
                border-radius: 0;
                z-index: 1; // occlude the list name

                // This is the same color as the left panel background because it needs
                // to occlude the sublist title
                background-color: $roomlist-bg-color;

                &::before {
                    top: 0;
                    left: 0;
                }
            }

            &.mx_RoomSublist_headerContainer:not(.mx_RoomSublist_headerContainer_withAux) {
                .mx_RoomSublist_menuButton {
                    bottom: 8px; // align to the middle of name, 40px less than the `bottom` above.
                }
            }
        }
    }
}

.mx_RoomSublist_contextMenu {
    padding: 20px 16px;
    width: 250px;

    hr {
        margin-top: 16px;
        margin-bottom: 16px;
        margin-right: 16px; // additional 16px
        border: 1px solid $roomsublist-divider-color;
        opacity: 0.1;
    }

    .mx_RoomSublist_contextMenu_title {
        font-size: $font-15px;
        line-height: $font-20px;
        font-weight: 600;
        margin-bottom: 4px;
    }

    .mx_RadioButton, .mx_Checkbox {
        margin-top: 8px;
    }
}

.mx_RoomSublist_addRoomTooltip {
    margin-top: -3px;
}

.mx_RoomSublist_skeletonUI {
    position: relative;
    margin-left: 4px;
    height: 288px;

    &::before {
        background: $roomsublist-skeleton-ui-bg;

        width: 100%;
        height: 100%;

        content: '';
        position: absolute;
        mask-repeat: repeat-y;
        mask-size: auto 48px;
        mask-image: url('$(res)/img/element-icons/roomlist/skeleton-ui.svg');
    }
}