Vaadin-combo-box: Allow specifying overlay width

We have the exact issue described;
For a location input, a typical code is "SVG", with caption "Stavanger Airport Sola"
This is an intranet app, so our users know most of the codes by heart, and want to write "SVG" instead of "Stavanger..."
Also, we have several of these next to each other in an editable grid. Space is tight, so we want the columns and comboboxes to be sized for the code, and not for the caption.

Vaadin suggested a workaround, which solves our immediate problem:

@CssImport
    ( id        = "vaadin-combo-box-overlay-override"
    , value     = "./styles/vaadin-combo-box-overlay.css"
    , themeFor  = "vaadin-combo-box-overlay"
    )

./styles/vaadin-combo-box-overlay.css:

:host {
     width: 500px !important;
}

Or, if you only want it on some comboboxes:

:host([theme~="large"]) {
     width: 500px !important;
}

combobox.getElement().setAttribute("theme", "large");

Duplicate of vaadin/vaadin-combo-box/issues/529.

See the suggested demo improvement at https://github.com/vaadin/vaadin-combo-box/issues/529#issuecomment-374611447

To dynamically update the ComboBox overlay width:

:host([theme="my-combo-box"]) {
  width: var(--my-combo-box-overlay-width, 200px) !important;
}

UI.getCurrent().getPage().executeJs("ShadyCSS.styleDocument({'--my-combo-box-overlay-width': $0 + 'px'})", newWidthAsInteger);

There is now a new feature in the web component to make this easier (closed issue https://github.com/vaadin/vaadin-combo-box/issues/529, see merged PR https://github.com/vaadin/vaadin-combo-box/pull/876)

This issue should now be about providing a helper method e.g. setOverlayWidth(String cssLength) for setting this new CSS custom prop --vaadin-combo-box-overlay-width.

I can confirm that the following code works nicely as suggested by @Haprog

comboBox.getElement().getStyle().set("--vaadin-combo-box-overlay-width", "400px")

The new docs site has examples of using a feature mentioned above:
https://vaadin.com/docs-beta/latest/ds/components/combo-box/#popup-width