geosolutions-it#9688: Make DOMUtils tests less dependent on platform-…

…varying browser default stylesheet (geosolutions-it#10046)

Co-authored-by: Florian Kellner <[email protected]>

web/client/utils/__tests__/DOMUtil-test.js

@@ -24,19 +24,22 @@ describe('Test the DOMUtils', () => {
         expect(spy.calls.length).toEqual(1);
     });
     it('test getOffsetTop', function() {
+        const desiredOffset = 8;
+        document.body.style.cssText = `margin: ${desiredOffset} px;`;
         document.body.innerHTML = `
         <div id="container">
             <div id="content">
             test
             </div>
         </div>`;
         const offset = getOffsetTop(document.querySelector("#content"));
-        expect(offset).toEqual(8);
+        expect(offset).toEqual(desiredOffset);
     });
     it('test getOffsetBottom', function() {
+        document.body.style.cssText = `margin: 8 px;`;
         document.body.innerHTML = `
         <div id="container">
-            <div id="content">
+            <div id="content" style="height: 18px">
             test
             </div>
         </div>`;