node-red/packages/node_modules/@node-red/editor-client/src/sass/ace.scss

.red-ui-editor, .red-ui-editor-dialog {

    .ace_read-only {
        .ace_scroller {
            background: $text-editor-background-disabled;
            color: $text-editor-color-disabled;
        }
        .ace_cursor {
           color: transparent !important;
        }
    }


    .ace_gutter {
        border-top-left-radius: 4px;
        border-bottom-left-radius: 4px;
    }
    .ace_scroller {
        border-top-right-radius: 4px;
        border-bottom-right-radius: 4px;
    }

    .ace_scroller {
        background: $text-editor-background;
        color: $text-editor-color;
    }
    .ace_marker-layer .ace_active-line {
        background: $text-editor-active-line-background;
    }
    .ace_marker-layer .ace_selection {
        background: $text-editor-selection-background;
        border-radius: 1px;
    }
    .ace_gutter-cell  {
        color: $text-editor-color;
    }
    .ace_gutter-active-line {
        background: $text-editor-gutter-active-line-background;
    }
    .ace_gutter {
        background: $text-editor-gutter-background;
    }
    .ace_tooltip {
        font-family: $primary-font;
        line-height: 1.4em;
        max-width: 400px;
        white-space: normal;
        background-image: none;
        background: $popover-background;
        color: $popover-color;
        border-radius: 4px;
        @include component-shadow;
        border-color: $popover-background;
    }

    #red-ui-event-log-editor {
        .ace_scroller {
            background: $event-log-background;
            color: $event-log-color;
        }
        .ace_marker-layer .ace_active-line {
            background: $event-log-active-line-background;
        }
        .ace_marker-layer .ace_selection {
            background: $event-log-selection-background;
        }
    }
}