Unexpected 2px "padding" in Dialog

[pavelkornev]

Describe the bug
When there is no headerText and there is nothing inside header slot, then 2px padding remains at the top of the dialog.

To reproduce

1. Create dialog without headerText and without header slot
2. Check the resulting rendering (see sandbox link below)

Isolated example
https://codesandbox.io/s/ui5-webcomponents-forked-gclih?file=/index.html

Expected behavior
ui5-popup-header-root is set to display: none when there is no headerText and there is nothing inside header slot

ui5-webcomponents/packages/main/src/Dialog.hbs

Lines 4 to 13 in bf8caaf

	<header
	class="ui5-popup-header-root"
	id="ui5-popup-header"
	@mousedown="{{_onDragMouseDown}}">
	{{#if header.length }}
	<slot name="header"></slot>
	{{else}}
	<h2 class="ui5-popup-header-text">{{headerText}}</h2>
	{{/if}}
	</header>

Screenshots

Affected components

• Dialog
• Popover

Organization: SAP Graph

Priority: Medium

[nnaydenow]

Hello @SAP/ui5-webcomponents-topic-rd,

As @pavelkornev mention header ui5-popup-header-root is still visible even it is empty and this leads to visual misalignments.

The issue is reproducible in:
https://codesandbox.io/s/ui5-webcomponents-forked-gclih?file=/index.html

Regards,
Nayden