upstream-zulip/web/styles/message_header.css

.message_header {
    vertical-align: middle;
    text-align: left;
    /* We can overflow-y if the font size gets big */
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    font-weight: 600;
    position: relative;
    z-index: 0;
    background-color: var(--color-background);

    .message-header-contents {
        font-size: 1.0714em; /* 15px at 14px em */
        line-height: 1.2;
        display: grid;
        grid-template-areas: "stream-label separator topic controls error date";
        grid-template-columns: minmax(0, 1fr) 0 0 0 auto auto;
        align-items: center;
        height: 1.8666em; /* 28px at 15px em */
        border: 1px solid var(--color-message-header-contents-border);
        border-bottom-color: var(--color-message-header-contents-border-bottom);
        border-radius: 7px 7px 0 0;
    }

    &.message_header_stream {
        /* Add box shadow to hide message border (first one) and message
           selected box shadow (second one) that are visible
           due to top borders of sticky recipient bar being curved. */
        box-shadow:
            -1px -5px 0 5px var(--color-background),
            1px -5px 0 0 var(--color-background);

        .message-header-contents {
            /* The separator column holds only the fixed-size chevron
               icon, so it gets an explicit width; the other columns
               hold variable-width content and stay auto/1fr. */
            grid-template-columns: auto 1em auto 1fr auto auto;
            align-items: stretch;
        }

        & .message_label_clickable {
            user-select: text;
            color: var(--color-text-message-header);

            &:hover {
                color: var(--color-text-message-header);
                text-decoration: none;
            }
        }

        & .message_label_clickable:focus {
            outline: none;
            text-decoration: none;
        }

        .stream_topic_separator {
            grid-area: separator;
            line-height: 0;
            display: flex;
            align-items: center;
            color: var(--color-message-header-icon-non-interactive);
            position: relative;
            top: 0.5px;
        }

        .stream_topic {
            grid-area: topic;
            display: flex;
            align-items: center;
            padding: 5px 6px 5px 2px;
            overflow: hidden;
            text-overflow: ellipsis;
            position: relative;
            top: 0.5px;

            .message_label_clickable.narrows_by_topic {
                overflow: hidden;
                text-overflow: ellipsis;

                span.stream-topic-inner {
                    white-space: pre;
                }
            }
        }

        .stream-privacy i {
            font-size: 1.0714em; /* 15px at 14px em */

            &.zulip-icon-globe,
            &.zulip-icon-hashtag {
                position: relative;
                top: -0.5px;
            }
        }

        .recipient_bar_controls {
            opacity: 0;
            transition: opacity 0.15s ease-out;
        }

        .recipient_bar_controls:focus-within {
            opacity: 1;
            transition: opacity 0.1s ease-in;
        }

        /* Show the bar controls on hover with a slight delay */
        &:hover {
            .recipient_bar_controls {
                opacity: 1;
                transition: opacity 0.15s ease-in 0.1s;
            }
        }

        /* Always show controls when header is sticky */
        &.sticky_header {
            .recipient_bar_controls {
                opacity: 1;
                transition: opacity 0.15s ease-in;
            }
        }
    }

    #report-message-preview-container & {
        /* We don't need these effects applied for message preview in the report
        message modal. */
        box-shadow: none;
        border: 0;
        background: transparent;
    }
}

.message_header_private_message {
    /* This is required for box-shadow appear above the message content. */
    z-index: 1;
    box-shadow:
        -1px -5px 0 5px var(--color-background),
        1px -5px 0 0 var(--color-background);
    background-color: var(--color-background);

    .message-header-contents {
        border-color: var(--color-private-message-header-border);
        border-bottom-color: var(--color-private-message-header-border-bottom);
        background-color: var(--color-background-private-message-header);
    }

    .message_label_clickable {
        user-select: text;
        display: flex;
        padding: 5px 0 5px 10px;
        font-weight: 600;
        height: 1.4142em; /* 19px at 14px em */
        line-height: 1.4142em; /* 19px at 14px em */
        color: var(--color-text-message-header);

        &:hover {
            color: var(--color-text-message-header) !important;
            text-decoration: none;
        }

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

        .private_message_header_icon {
            font-size: 1.0714em; /* 15px at 14px em */
            position: relative;
            top: 1px;
            width: 1.0666em; /* 16px at 15px em */
            height: 1.0666em; /* 16px at 15px em */
        }

        .private_message_header_name {
            overflow: hidden;
            text-overflow: ellipsis;

            i.zulip-icon-bot {
                vertical-align: middle;
                position: relative;
                top: -1px;
                padding-left: 0.3em;
            }
        }
    }
}

.message-feed {
    .recipient_row {
        /* Browser overlaps extra top padding of message header and
           the bottom border message if this margin is not present. */
        margin-bottom: 1px;
        border-radius: 5px;

        .message_row:last-of-type {
            border-radius: var(--last-message-row-border-radius);
            border-bottom: 1px solid var(--color-message-list-border);

            .unread-marker-fill {
                border-radius: 0 0 0 7px;
                height: calc(100% - 2px);
            }

            .messagebox {
                border-radius: 0 0 7px 7px;
                padding-bottom: 4px;
            }
        }

        .message_header + .message_row {
            .messagebox {
                padding-top: 5px;
            }
        }

        .recipient_row_date {
            cursor: pointer;
        }
    }

    .message_header {
        position: sticky;
        top: var(--navbar-fixed-height);
        /* Needs to be higher than the z-index of date_row. */
        z-index: 4;
        box-shadow: 0 -1px 0 0 var(--color-background);

        .message-header-contents {
            margin-top: var(--header-padding-bottom);
        }

        &.sticky_header {
            box-shadow: var(--unread-marker-left) -1px 0 0
                var(--color-background);

            .recipient_row_date {
                display: flex;
            }
        }
    }
}

.stream_label {
    grid-area: stream-label;
    display: flex;
    align-items: center;
    gap: 5px;
    padding: 5px 2px 5px 10px;
    position: relative;
    top: 0.5px;
    text-decoration: none;
    font-weight: 600;
    overflow: hidden;

    .zulip-icon.zulip-icon-globe {
        position: relative;
        top: 1px;
    }

    &:hover {
        text-decoration: none;
    }

    .stream-privacy {
        min-width: unset;
        width: 1.1428em; /* 16px at 14px em */
        height: 1.1428em; /* 16px at 14px em */
        display: flex;
        justify-content: center;
        align-items: center;

        .hashtag {
            padding-right: 0;

            &::after {
                font-size: 1.1428em; /* 16px at 14px em */
            }
        }
    }

    .message-header-stream-name {
        overflow: hidden;
        text-overflow: ellipsis;
    }

    .message-header-stream-archived {
        color: var(--color-text-message-header-archived);
    }
}

.recipient_bar_controls {
    grid-area: controls;
    display: flex;
    align-items: center;

    &.topic-edit-mode .recipient-bar-control {
        display: none;
    }
}

.on_hover_topic_read {
    opacity: 0.7;

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

.error-icon-message-recipient {
    grid-area: error;
}

.recipient_row_date {
    grid-area: date;
    color: var(--color-date);
    font-size: calc(12em / 14);
    padding: 0 10px;
    text-align: right;
    display: flex;
    align-items: center;
    font-style: normal;
    font-weight: 600;
    line-height: 17px; /* identical to box height, or 131% */
    letter-spacing: 0.04em;
    text-transform: uppercase;
    padding-top: 1px;

    /* Display the date when unchanged only for sticky headers. */
    &.recipient_row_date_unchanged {
        display: none;

        .sticky_header & {
            display: flex;
        }
    }

    &.hide-date-separator-header {
        display: none;
    }
}

.recipient_bar_icon {
    color: var(--color-message-header-icon-interactive);
    opacity: 0.2;
    padding-left: 6px;
    padding-right: 6px;

    &:hover {
        opacity: 0.4 !important;
        cursor: pointer;
    }
}

.spectator-view .recipient_bar_controls .recipient-bar-control {
    &.recipient-bar-copy-link-to-topic {
        display: flex;
    }

    &.recipient-row-topic-menu {
        display: none;
    }
}

@container message-lists (width <  $cq_ml_min) {
    .recipient-bar-control {
        display: none;

        /* Always show the vdots */
        &.recipient-row-topic-menu {
            display: block;
        }
    }
}

@media (width < $ml_min) {
    .without-container-query-support {
        .recipient-bar-control {
            display: none;

            /* Always show the vdots */
            &.recipient-row-topic-menu {
                display: block;
            }
        }
    }
}