zulip/web/styles/left_sidebar.css

/* The width of the empty space in the sidebar to separate
   content from the edge of the window */
$far_left_gutter_size: 10px;
/* This represents the space in the sidebar reserved for symbols like
   the #; labels like the the stream name go to the right of this. */
$left_col_size: 19px;
/* The full topic indentation includes 4px of indent in addition to
   the above (and another 5px of padding not measured here) */
$topic_indent: calc($far_left_gutter_size + $left_col_size + 4px);
$topic_resolve_width: 13px;
/* Space between section in the left sidebar. */
$sections_vertical_gutter: 8px;
$bottom_scrolling_buffer: 25px;
/* space direct message / stream / topic names from unread counters
and @ mention indicators by 3px on the right */
$before_unread_count_padding: 3px;

.hashtag {
    &:empty {
        &::after {
            content: "#";
            line-height: 0;
            font-size: 18px;
            font-weight: 700;
        }
    }
}

#streams_list .stream-privacy {
    height: 16px;
    font-weight: 700;
    text-align: center;

    .zulip-icon.zulip-icon-globe {
        font-size: 12px;
    }

    .zulip-icon.zulip-icon-hashtag {
        font-size: 13px;
    }

    .zulip-icon.zulip-icon-lock {
        font-size: 13px;
        /* Slight vertical adjustment so the lock
           doesn't sit too high, relative to the
           other stream icons. */
        padding-top: 2px;
    }
}

.sidebar-topic-check,
.topic-name,
.topic-markers-and-controls {
    cursor: pointer;
}

#left-sidebar-navigation-list .filter-icon i {
    color: var(--color-left-sidebar-navigation-icon);
}

#stream_filters,
#left-sidebar-navigation-list {
    margin-right: 12px;
}

li.show-more-topics {
    & a {
        font-size: 12px;
    }
}

#streams_inline_icon,
.streams_filter_icon {
    float: right;
    opacity: 0.5;
    padding: 3px;
    margin-left: 4px;

    &:hover {
        opacity: 1;
        cursor: pointer;
    }
}

.streams_inline_icon_wrapper {
    float: right;
    margin-right: 8px;
}

.streams_filter_icon.web_public {
    margin-right: 10px;
}

.tooltip {
    max-width: 18em;
}

#stream_filters {
    overflow: visible;
    margin-bottom: 5px;
    margin-right: 12px;
    padding: 0;
    font-weight: normal;

    .input-append.topic_search_section {
        padding: 2px 0 2px calc($topic_indent - $topic_resolve_width);
        margin-bottom: 3px;
        margin-left: 3px;

        & input {
            width: calc(100% - 50px);
        }

        .clear_search_button {
            margin-left: -1px;
        }
    }

    & li {
        & a:hover {
            text-decoration: none;
        }

        & ul {
            margin-left: 0;

            &.topic-list li {
                padding: 2px 0;

                &.filter-topics {
                    padding-bottom: 0;
                    position: sticky;
                    top: calc($sections_vertical_gutter + 43px);
                    z-index: 2;
                }
            }
        }
    }

    .stream-with-count.hide_unread_counts {
        .masked_unread_count {
            display: block;
            /* Shift masked dot to align with
               the least-significant digit on
               unreads in other rows.
               We have to do this with margin,
               because width or padding will
               distort the CSS-created dot. */
            margin-right: 3px;
        }

        .unread_count {
            display: none;
        }
    }

    .narrow-filter
        > .bottom_left_row:hover
        > .stream-with-count.hide_unread_counts {
        .masked_unread_count {
            display: none;
        }

        .unread_count {
            display: inline;
        }
    }

    .stream-expanded {
        .stream-with-count.hide_unread_counts {
            .masked_unread_count {
                display: none;
            }

            .unread_count {
                display: inline;
            }
        }
    }

    .has-unmuted-unreads.hide_unread_counts {
        .masked_unread_count {
            display: none;
        }

        .unread_count {
            display: inline;
        }
    }

    .inactive_stream:not(.active-filter) {
        opacity: 0.5;
    }

    .toggle_stream_mute {
        margin-right: 3px;
        opacity: 0.5;

        &:hover {
            opacity: 1;
        }
    }
}

.left-sidebar-navigation-area {
    & li a {
        &:hover {
            text-decoration: none;
        }
    }
}

#left_sidebar_scroll_container {
    outline: none;
    overflow-x: hidden;
    overflow-y: auto;
    position: relative;
    z-index: 0;
    width: 100%;

    .direct-messages-container {
        /* TODO: Clean up this value and the
           analogous one on #stream-filters;
           this could be done alongside the
           --left-sidebar-collapse-widget-gutter
           cleanup so that all of the left sidebar
           space is better, more uniformly handled.
           That will be an essential pre-condition
           for a resizable left sidebar. */
        margin-right: 12px;
        margin-left: 0;
    }
}

.direct-messages-container {
    margin-right: 16px;
    margin-left: 6px;
    z-index: 1;

    #private_messages_section_header {
        cursor: pointer;
        padding: 0 10px 1px 6px;
        white-space: nowrap;

        #show_all_private_messages {
            right: 0;
            float: right;
            position: absolute;
            opacity: 0.7;
            text-decoration: none;
            color: inherit;
            margin-right: 21px;
            margin-top: 1px;

            &:hover {
                opacity: 1;
            }
        }

        .unread_count {
            margin-right: 16px;
            margin-top: 2px;
        }
    }

    & ul.dm-list {
        list-style-type: none;
        font-weight: 400;
        margin-left: 0;
        margin-bottom: 0;

        & span.fa-group {
            font-size: 90%;
        }

        & li.dm-list-item {
            & a {
                text-decoration: none;
                color: inherit;
            }

            .fa-group,
            .zulip-icon {
                opacity: 0.7;
            }
        }

        & li#show-more-direct-messages {
            cursor: pointer;
            padding-right: 26px;
            /* TODO: Rewrite the show-more and show-less
               buttons as grids alongside the left sidebar
               header rewrites. This padding value
               is a stopgap to provide the same lefthand
               alignment as the "more topics" text, which
               aligns with the topic above--just as this
               aligns with the DM row above. */
            padding-left: 29px;

            & a {
                font-size: 12px;
            }

            .unread_count {
                margin-top: 2px;
            }
        }
    }
}

#toggle_private_messages_section_icon,
#toggle-top-left-navigation-area-icon {
    opacity: 0.7;
    margin-left: -15px;
    min-width: 12px;

    &.fa-caret-right {
        position: relative;
        left: 3px;
    }

    &:hover {
        opacity: 1;
    }

    &:focus {
        outline: 0;
    }

    /* This renders an outline when the caret is reached
       with the keyboard, although that is not at present
       easily accomplished. */
    &:focus-visible {
        outline: 2px solid var(--color-outline-focus);
    }
}

.active_private_messages_section {
    #private_messages_section,
    #direct-messages-list,
    #hide-more-direct-messages {
        background-color: hsl(202deg 56% 91%);
    }

    #private_messages_section {
        border-radius: 4px 4px 0 0;
    }

    #direct-messages-list {
        border-radius: 0 0 4px 4px;
    }

    #more_private_messages_sidebar_title {
        font-weight: 600;
    }
}

:not(.active-sub-filter) {
    &.top_left_row:hover,
    &.bottom_left_row:hover {
        background-color: var(--color-background-hover-narrow-filter);
        border-radius: 4px;
    }
}

#stream_filters .narrow-filter.highlighted_stream {
    &.active-filter > .bottom_left_row {
        background-color: var(--color-background-hover-narrow-filter);
    }

    &.active-filter .topic-list .bottom_left_row {
        background-color: var(--color-background-active-narrow-filter);
    }

    .bottom_left_row:not(.active-sub-filter) {
        background-color: var(--color-background-hover-narrow-filter);
    }
}

#login-link-container,
#subscribe-to-more-streams {
    text-decoration: none;
    margin: 5px auto 5.5px 10px;
    margin-bottom: $bottom_scrolling_buffer;

    & i {
        min-width: 19px;
        text-align: center;

        &::before {
            padding-right: 3px;
        }
    }
}

ul.filters {
    list-style-type: none;
    margin-left: 0;
    color: hsl(0deg 0% 20% / 100%);

    & a {
        color: inherit;

        &:focus {
            text-decoration: none;
        }
    }

    & hr {
        margin-top: 10px;
        margin-bottom: 10px;
    }

    .has-only-muted-unreads {
        .unread_count {
            opacity: 0.5;
        }
    }

    .has-only-muted-mentions .unread_mention_info {
        opacity: 0.5;
    }

    /* This is a noop in the current design, because unread counts for
       muted streams have the same opacity, but the logic is here to
       be explicit and because the design may change in the future. */
    .more_topic_unreads_muted_only .unread_count {
        opacity: 0.5;
    }

    & li.muted_topic,
    li.out_of_home_view {
        color: hsl(0deg 0% 20% / 50%);

        .has-unmuted-mentions .unread_mention_info {
            color: hsl(0deg 0% 20%);
        }

        .stream-privacy {
            opacity: 0.5;
        }

        & .unread_count {
            opacity: 0.5;
        }

        & .masked_unread_count {
            opacity: 0.5;
        }

        .has-unmuted-unreads {
            .unread_count {
                opacity: 1;
            }
        }

        & li.unmuted_or_followed_topic {
            color: var(--color-unmuted-or-followed-topic-list-item);

            .unread_count {
                opacity: 1;
            }
        }
    }

    & li.out_of_home_view {
        &:hover {
            color: hsla(0deg 0% 20% / 75%);

            .stream-privacy {
                opacity: 0.75;
            }

            .unread_count {
                opacity: 0.75;
            }

            .has-unmuted-unreads {
                .unread_count {
                    opacity: 1;
                }
            }
        }

        & li.muted_topic {
            /* If stream is muted, this resets opacity of muted topics in muted
            stream to 1; since opacity is multiplied down through child
            elements, this avoids an unreadably low opacity. */
            opacity: 1;
        }
    }
}

li.active-filter,
li.active-sub-filter {
    font-weight: 600 !important;
    position: relative;
    border-radius: 4px;
    background-color: var(--color-background-active-narrow-filter);
}

#stream_filters .narrow-filter.active-filter {
    .topic-list .filter-topics,
    > .bottom_left_row {
        background-color: var(--color-background-active-narrow-filter);
        border-radius: 4px;
    }
}

#left-sidebar-navigation-list-condensed {
    display: flex;
    justify-content: center;

    .left-sidebar-navigation-condensed-item {
        /* 24px minimum width from Vlad's design. */
        flex: 1 0 24px;
        /* Unset padding from individual top_left items */
        padding: 0;
        border-radius: 4px;
        /* Set a positioning context for the unread dot. */
        position: relative;

        .unread_count {
            position: absolute;
        }

        /* Show the same styles when each item is
           hovered or, via the keyboard, the `<a>`
           element within receives focus. */
        &:hover,
        &:focus-within {
            background: var(--color-background-hover-narrow-filter);

            .unread_count {
                top: -6px;
                right: -6px;
                background: var(--color-background-unread-counter-no-alpha);
            }
        }

        &:not(:hover) .unread_count {
            top: 2px;
            right: 2px;
            width: 6px;
            height: 6px;
            font-size: 0;
            padding: 0;
            background-color: var(--color-background-unread-counter-dot);
        }

        &.top_left_starred_messages .unread_count {
            display: none;
        }
    }

    .left-sidebar-navigation-icon-container {
        /* Unset margin from full nav list anchor elements. */
        margin: 0;
        /* Horizontally center icons within their boxes. */
        text-align: center;

        &:focus {
            /* Unset inherited :focus outline. */
            outline: 0;
        }
    }

    .active-filter {
        /* Don't display a background on condensed icons. */
        background: unset;
    }

    .filter-icon {
        display: flex;
        align-items: center;
        justify-content: center;
        /* TODO: Set this 24px height value as a variable.
           Keep filter-icon height the full height of the box. */
        height: 24px;
        /* Enlarge icons slightly in condensed views. */
        font-size: 15px;
        color: var(--color-left-sidebar-navigation-icon);
    }
}

#left-sidebar-navigation-list {
    margin-bottom: $sections_vertical_gutter;
    /* We display this as a grid only to control
       the order of home views, using a single
       named grid area. */
    display: grid;
    grid-template-areas: "selected-home-view";

    .left-sidebar-navigation-label-container {
        .left-sidebar-navigation-label {
            overflow: hidden;
            text-overflow: ellipsis;
            white-space: nowrap;
        }
    }
}

.selected-home-view {
    /* This bumps the selected view to the
       top of the grid (expanded list).
       Others items will auto place in the
       remaining auto-generated grid rows. */
    grid-area: selected-home-view;
    /* The condensed view is a flexbox, so
       here we'll use a negative order to
       bump the selected home view to the
       start of the flexbox (lefthand side). */
    order: -1;
}

.top_left_starred_messages .unread_count,
.top_left_drafts .unread_count,
.top_left_scheduled_messages .unread_count,
.condensed-views-popover-menu .unread_count {
    background-color: unset;
    color: inherit;
    border: 0.5px solid var(--color-border-unread-counter);
}

/* Don't show unread counts on views... */
.top_left_inbox,
.top_left_recent_view,
.top_left_all_messages {
    .unread_count {
        visibility: hidden;
    }
    /* ...unless it's the selected home view. */
    &.selected-home-view .unread_count {
        visibility: visible;
    }
}

/* Don't show the scheduled messages item... */
li.top_left_scheduled_messages {
    display: none;
    /* ...unless there are scheduled messages to show. */
    &.show-with-scheduled-messages {
        /* Use display: grid to preserve the grid
           layout when visible. */
        display: grid;
    }
}

.top_left_row {
    /* The row grid for the outer .top_left_row
       is chiefly for lefthand spacing and placing
       the inner row content and vdots. */
    grid-template-columns: 7px 0 minmax(0, 1fr) 0 30px 0;

    .sidebar-menu-icon {
        grid-area: ending-anchor-element;
    }
}

.left-sidebar-navigation-label-container {
    grid-area: row-content;
    /* The label container itself is also a grid,
       for laying out the items that are its
       children. Same template areas, different
       column widths. */
    grid-template-columns: 0 22px minmax(0, 1fr) max-content 0 0;
    /* This is a legacy value, from a former
       1px of top padding on top_left_row plus
       an inner 1px top margin on `<a>` elements.

       These are added here, rather than on the label
       container, to keep all hovered/highlighted areas
       clickable.

       This complicates true centering within a
       row highlight. It might be better to make
       these both 2px.
    */
    padding-top: 2px;
    padding-bottom: 1px;

    .filter-icon {
        grid-area: starting-anchor-element;
        /* Use a flex container to handle
           icon centering within the grid area. */
        display: flex;
        justify-content: center;
    }

    .left-sidebar-navigation-label {
        grid-area: row-content;
        padding-right: $before_unread_count_padding;
    }

    .unread_count {
        grid-area: markers-and-controls;
    }
}

.conversation-partners {
    grid-area: row-content;
    /* Set an 18px line-height to better vertically
       center user circles and icons (both of which
       have even heights). */
    line-height: 18px;
    overflow: hidden;
    text-overflow: ellipsis;
    /* Use an inline grid to provide a modern layout
       for status emoji in DM rows, while preserving
       the expected ellipsis behavior on long usernames
       or large DM groups.
       The 16px-tall emoji will also align well
       vertically with the 18px line-height here. */
    display: inline-grid;
    /* Provide a two-column grid, sized to accommodate
       the content of the conversation list and status
       emoji, if any. */
    grid-template-columns: repeat(2, minmax(0, max-content));
    align-items: center;
}

.conversation-partners .status-emoji {
    /* Prevent status emoji from colliding
       with unread counts. */
    margin-right: 3px;
}

/* New .topic-box grid definitions here. */
#views-label-container,
.top_left_row,
.left-sidebar-navigation-label-container,
.dm-box,
.subscription_block,
.topic-box {
    display: grid;
    align-items: center;
    /* This general pattern of elements applies to every single row in the left
       sidebar, to some degree or another. Eventually, these template areas
       could be applied to all rows, with different `grid-template-column`
       values applied as needed (and shared as needed). For example, an element
       with no "starting-offset" sets that area to `0`; so too with other non-
       existent elements.

       The offsets themselves are meant to greedily assign all of the available
       horizontal space to the content area of the row. That space can then be
       modified or reassigned as needed, without running up against `padding`
       (which alters the box size) or `margin` (which notoriously bleeds outside
       of the element it's defined on). */
    grid-template-areas: "starting-offset starting-anchor-element row-content markers-and-controls ending-anchor-element ending-offset";
}

#views-label-container {
    grid-template-columns:
        0 15px minmax(0, 0.5fr) minmax(0, 1fr)
        30px 12px;
    /* Base height on 24px icon-target area from Vlad's design. */
    grid-template-rows: 24px;
    /* TODO: Rewrite the `--left-sidebar-collapse-widget-gutter`
       value and the styles dependent on it so that this kind of
       1990s layout shenanigans is made unnecessary. */
    margin-left: -3px;
    cursor: pointer;

    &.showing-expanded-navigation {
        /* When the expanded navigation is visible,
           hide the condensed navigation's controls. */
        #left-sidebar-navigation-list-condensed,
        .left-sidebar-navigation-menu-icon {
            display: none;
        }
        /* Give the sidebar title through the end of the markers
           area, if needed. */
        .sidebar-title {
            grid-column: row-content-start / markers-and-controls-end;
        }
    }

    /* Use a next-sibling combinator (+) to use CSS to show and hide
       filter rows as needed, based on the narrow. */
    &.showing-condensed-navigation {
        + #left-sidebar-navigation-list {
            /* When the navigation area is condensed, hide all
               the rows in the full navigation list... */
            & .top_left_row {
                display: none;
            }
            /* ...except when there is an active filter in place:
               that row should still be shown. */
            & .top_left_row.active-filter {
                display: grid;
            }
        }
    }

    #toggle-top-left-navigation-area-icon {
        grid-area: starting-anchor-element;
        /* Remove negative left margin. This should be cleaned
           up along with the `--left-sidebar-collapse-widget-gutter`
           matters above. */
        margin-left: 0;
    }

    .sidebar-title {
        grid-area: row-content;
        /* Override heading margin from Bootstrap. */
        margin: 0;
        /* Show an ellipsis on the VIEWS header when
           it won't sit adjacent the icons in their
           most condensed presentation. */
        overflow: hidden;
        text-overflow: ellipsis;
    }

    #left-sidebar-navigation-list-condensed {
        margin: 0;
        grid-area: markers-and-controls;
    }

    .left-sidebar-navigation-menu-icon {
        grid-area: ending-anchor-element;
        /* Horizontally center vdots. */
        justify-self: center;
        /* Properly size vdots. */
        font-size: 17px;
        /* Occupy same clickable height as
           other condensed-view icons */
        height: 24px;
        /* Vertically center dots with
           flexbox. */
        display: flex;
        align-items: center;
        color: var(--color-left-sidebar-header-vdots-visible);

        &:hover {
            color: var(--color-vdots-hover);
        }
    }
}

.condensed-views-popover-menu {
    .left-sidebar-popover-icon-label-count {
        display: flex;
        align-items: baseline;
    }

    .filter-icon {
        align-self: center;
        height: 15px;
    }

    .left-sidebar-navigation-label {
        flex: 1 0 0;
        margin-left: 3px;
    }

    .unread_count {
        margin-left: 6px;
        border-color: var(--color-border-unread-counter-popover-menu);
    }
}

.subscription_block {
    grid-template-columns:
        7px 22px minmax(0, 1fr) minmax(0, max-content)
        30px 0;
    white-space: nowrap;

    .stream-privacy {
        grid-area: starting-anchor-element;
    }

    .stream-name {
        grid-area: row-content;
    }
}

.topic-box {
    /* Padding from original .topic-box definition. */
    padding-top: 1px;
    grid-template-columns:
        25px $topic_resolve_width minmax(0, 1fr) minmax(0, max-content)
        30px 0;
}

.topic-box .zero_count {
    display: none;
}

.sidebar-topic-check {
    grid-area: starting-anchor-element;
    font-size: 15px;
    height: 20px;
}

.topic-name {
    grid-area: row-content;
    padding: 1px $before_unread_count_padding 1px 0;

    /* TODO: We should figure out how to remove this without changing the spacing */
    line-height: 1.1;

    /* TODO: Consolidate these styles with conversation partners and stream name
       once grid rewrite is complete on all sidebar rows.

       Also: note that these styles will be moot for topic names once we allow
       for multiline topics. If we hold multiline topics to a certain number
       of lines, we'll likely need a JavaScript-based solution like Clamp.js
       to display an ellipsis on the final visible line. */
    white-space: nowrap;
    /* Both `hidden` and `clip` are shown for the sake
       of older browsers that do not support `clip`. */
    overflow-x: hidden;
    overflow-x: clip;
    text-overflow: ellipsis;
}

.stream-markers-and-controls,
.topic-markers-and-controls {
    grid-area: markers-and-controls;
    display: flex;
    /* Present a uniform space between icons */
    gap: 5px;
    align-items: center;

    .unread_mention_info {
        /* Unset margin in favor of flex gap. */
        margin: 0;
    }

    .unread_count {
        /* Height is set here by the flexbox; this
           decouples .unread_count from the app-wide
           definition. */
        height: auto;
    }
}

.bottom_left_row .sidebar-menu-icon {
    grid-area: ending-anchor-element;
}

.conversation-partners-list,
.stream-name {
    white-space: nowrap;
    overflow-x: hidden;
    overflow-x: clip;
    text-overflow: ellipsis;
    padding: 1px $before_unread_count_padding 1px 0;
}

.conversation-partners-list {
    /* TODO: See about consolidating or re-expressing
       .stream-name spacing so as to not require
       padding there, either. */
    padding: 0;
}

/*
    All of our left sidebar handlers use absolute
    positioning.  We should fix that.
*/
.bottom_left_row .sidebar-menu-icon,
.top_left_row .sidebar-menu-icon {
    display: none;
    width: 100%;
    cursor: pointer;
    /* Use a flex container to handle
       icon centering within the grid area.
       :hover actually sets the `display: flex`,
       so it remains hidden otherwise. */
    justify-content: center;
    text-align: center;
    /* Set the icon size, which will be inherited
       by .zulip-icon */
    font-size: 17px;

    /*
        If you hover directly over the ellipsis itself,
        show it in black.
    */

    &:hover {
        color: var(--color-vdots-hover);
    }

    /*
        Hover does not work for touch-based devices like mobile phones.
        Hence the the icons does not appear, making the user unaware of its
        presence on such devices. The following media property displays the
        icon by default for such behaviour.
    */

    @media (hover: none) {
        display: flex;
        /* Show dots on touchscreens in a less distracting,
           lighter shade. */
        color: var(--color-vdots-hint);
    }
}

/*
    When you hover over list items, we hover
    the vdots in light gray.

    The stream icon should always display when
    any topic is hovered, which is why it gets
    a more specific selector here.
*/
#stream_filters li:hover .stream-sidebar-menu-icon,
.top_left_row:hover .sidebar-menu-icon,
.bottom_left_row:hover .sidebar-menu-icon,
.column-left .left-sidebar .left_sidebar_menu_icon_visible {
    /* We push against `display: none` with
       `display: flex` because the sidebar vdots
       all expect to be displayed as flex items
       when visible. Their vertical alignment
       depends on it, too. */
    display: flex;
    color: var(--color-vdots-visible);

    /*
        If you hover directly over the vdots icon,
        show it in black.
    */
    &:hover {
        color: var(--color-vdots-hover);
    }
}

/*
    For topic ellipsis-v(vertical 3 dots) we use a slightly smaller
    font to show they're "lower" in the hierarchy,
    which also affects it positioning.
*/
.topic-sidebar-menu-icon {
    /* 0.9em, but with a pixel value because the
       ordinary 17px vdots size is not inherited
       here, so we can't express an em-value
       directly. Pixels are easier to reason
       about with icons, anyway. */
    font-size: 15.3px;
}

ul.topic-list {
    list-style-type: none;
    font-weight: normal;
}

li.topic-list-item {
    position: relative;
    padding-right: 5px;
}

.dm-box {
    grid-template-columns: 7px 22px minmax(0, 1fr) minmax(0, max-content) 30px 0;
    /* This padding maintains a 22px height on DM rows. */
    padding: 2.25px 0;

    .conversation-partners-icon {
        grid-area: starting-anchor-element;
        justify-self: center;
        align-self: center;
    }

    .user_circle {
        width: 8px;
        height: 8px;
        /* TODO: Remove these after right-sidebar
           row rewrites. */
        float: none;
        position: static;
    }

    .zulip-icon.zulip-icon-bot {
        font-size: 90%; /* Reduce the bulkiness of this icon */
        padding: 3px 0 3px 1px; /* Shift reduced icon a pixel left to maintain horizontal centering. */
    }

    .unread_count {
        grid-area: markers-and-controls;
        /* TODO: This is an alternative method
           for presenting a 16px-tall unread
           counter, regardless of context. This
           method could be used app-wide once
           all of the layout methods for presenting
           unreads have been modernized.

           Set the line-height to match the
           font-size, so that the numerals sit in
           a 12px box. */
        line-height: 12px;
        /* Use flexbox to vertically center
           the 12px-high text node within the
           16px-high unread box. */
        display: flex;
        align-items: center;
    }
}

.zoom-out {
    #topics_header {
        display: none;
    }

    .zoom-out-hide {
        display: none;
    }
}

#topics_header {
    position: sticky;
    top: 0;
    z-index: 2;
    margin-right: 10px;
    padding-top: $sections_vertical_gutter;
    color: hsl(0deg 0% 43%);
    background-color: var(--color-background);

    .show-all-streams {
        color: inherit;
        text-decoration: none;
        text-transform: uppercase;
        margin-left: calc($far_left_gutter_size + 2px);

        & i {
            margin: 0 6px 0 13px;
            position: relative;
            top: 1px;
        }
    }
}

#streams_header {
    margin-right: 12px;
    cursor: pointer;
    padding: $sections_vertical_gutter 0 3px calc($far_left_gutter_size + 2px);
    position: sticky;
    background-color: var(--color-background);
    /* Ideally, 0px should work here, but maybe simplebar is doing something
       that is creating `0.5px` extra gap in zoomed-in windows. */
    top: -0.5px;
    z-index: 1;

    .input-append {
        white-space: nowrap;
        margin-bottom: 10px;

        & input {
            padding-right: 20px;
        }

        .clear_search_button {
            margin-left: -1px;
        }
    }
}

.streams_subheader {
    font-size: 0.8em;
    font-weight: normal;
    padding-left: $far_left_gutter_size;
    cursor: pointer;
    text-align: center;
    margin-right: 12px;
    color: hsl(240deg 10% 50%);

    & span {
        display: flex;
        flex-direction: row;
        width: 100%;
        left: 0.5em;
        right: 0.5em;
        opacity: 0.5;
    }

    & span::before,
    span::after {
        content: " ";
        flex: 1 1;
        vertical-align: middle;
        margin: auto;
        border: 0.5px solid hsl(240deg 10% 50%);
        opacity: 0.2;
    }

    & span::before {
        margin-right: 0.5em;
    }

    & span::after {
        margin-left: 0.5em;
    }
}

.stream-list-filter {
    width: 216px;
    white-space: nowrap;
    text-overflow: ellipsis;
    overflow: hidden;
}

.topic-list-filter {
    /* Input width = 100% - 30px right-margin - 6px right-padding */
    /* To keep the right edge of input along with its borders inline with other
       topic items we consider to subtract the space given for right margin of
       other items, and right padding of input element.  */
    width: calc(100% - 36px);
}

.zero_count {
    visibility: hidden;
}

.zero-topic-unreads.show-more-topics .topic-box {
    margin-right: 30px;
}

.searching-for-more-topics img {
    height: 16px;
    margin-left: 6px;
}

.zoom-in {
    .narrow-filter > .bottom_left_row {
        position: sticky;
        top: calc($sections_vertical_gutter + 20px);
        z-index: 2;
        padding-bottom: 1px;
        background-color: var(--color-background);
    }

    #subscribe-to-more-streams,
    .show-more-topics {
        display: none;
    }

    &.direct-messages-container ul.dm-list {
        margin-bottom: $bottom_scrolling_buffer;
    }

    #more_private_messages_sidebar_title {
        display: inline;
    }

    #hide-more-direct-messages {
        display: block;
        text-decoration: none;
        color: inherit;
        font-size: 12px;

        & span {
            display: block;
            /* TODO: Rewrite the show-more and show-less
               buttons as grids alongside the left sidebar
               header rewrites. The 6px left padding here
               aligns the "back to streams" text with the
               DIRECT MESSAGES heading above. */
            padding: 2px 0 2px 6px;
        }

        &:hover {
            & span {
                background-color: hsl(120deg 12.3% 71.4% / 38%);
                border-radius: 4px;
            }
        }
    }

    .zoom-in-hide {
        display: none;
    }

    .zoom-in-sticky {
        position: sticky;
        top: 0;
        z-index: 1;
        padding: 3px 0 3px $far_left_gutter_size;
    }

    #show_all_private_messages {
        margin-right: 5px !important;
    }
}