Step 14: Custom CSS and Theme Colors

Sometimes we need to define some more fine-granular layouts and this is when we can use the flexibility of CSS by adding custom style classes to controls and style them as we like.

Preview

The space between the button and the input field is now smaller and the output text is bold

Caution:

As stated in the Compatibility Rules, the HTML and CSS generated by OpenUI5 is not part of the public API and may change in patch and minor releases. If you decide to override styles, you need to test and update your modifications each time OpenUI5 is updated. A prerequisite for this is that you have control over the version of OpenUI5 being used, for example in a standalone scenario.

Coding

You can view and download all files at Walkthrough - Step 14.

webapp/css/style.css (New)

html[dir="ltr"] .myAppDemoWT .myCustomButton.sapMBtn {
   margin-right: 0.125rem
}

html[dir="rtl"] .myAppDemoWT .myCustomButton.sapMBtn {
   margin-left: 0.125rem
}

.myAppDemoWT .myCustomText {
   display: inline-block;
   font-weight: bold;
}

We create a folder css which will contain our CSS files. In a new style definition file inside the css folder we create our custom classes combined with a custom namespace class. This makes sure that the styles will only be applied on controls that are used within our app.

A button has a default margin of 0 that we want to override: We add a custom margin of 2px (or 0.125rem calculated relatively to the default font size of 16px) to the button with the style class myCustomButton. We add the CSS class sapMBtn to make our selector more specific: in CSS, the rule with the most specific selector "wins".

For right-to-left (rtl) languages, like Arabic, you set the left margin and reset the right margin as the app display is inverted. If you only use standard OpenUI5 controls, you don't need to care about this, in this case where we use custom CSS, you have to add this information.

In an additional class myCustomText we define a bold text and set the display to inline-block. This time we just define our custom class without any additional selectors. We do not set a color value here yet, we will do this in the view.

webapp/manifest.json

...
  "sap.ui5": {
	...	
	"rootView": {
	  ...
	},
	"resources": {
	  "css": [
		{
		  "uri": "css/style.css"
		}
	  ]
	}
  }

In the resources section of the sap.ui5 namespace, additional resources for the app can be loaded. We load the CSS styles by defining a URI relative to the component. OpenUI5 then adds this file to the header of the HTML page as a <link> tag, just like in plain Web pages, and the browser loads it automatically.

webapp/view/App.view.xml

<mvc:View
	controllerName="ui5.walkthrough.controller.App"
	xmlns="sap.m"
	xmlns:mvc="sap.ui.core.mvc"
	displayBlock="true">
	<Shell>
		<App class="myAppDemoWT">
			<pages>
				<Page title="{i18n>homePageTitle}">
					<content>
						<Panel
							headerText="{i18n>helloPanelTitle}"
							class="sapUiResponsiveMargin"
							width="auto">
							<content>
								<Button
									text="{i18n>showHelloButtonText}"
									press=".onShowHello"
									class="myCustomButton"/>
								<Input
									value="{/recipient/name}"
									valueLiveUpdate="true"
									width="60%"/>
								<FormattedText
									htmlText="Hello {/recipient/name}"
									class="sapUiSmallMargin sapThemeHighlight-asColor myCustomText"/>
							</content>
						</Panel>
					</content>
				</Page>
			</pages>
		</App>
	</Shell>
</mvc:View>

The app control is configured with our custom namespace class myAppDemoWT. This class has no styling rules set and is used in the definition of the CSS rules to define CSS selectors that are only valid for this app.

We add our custom CSS class to the button to precisely define the space between the button and the input field. Now we have a pixel-perfect design for the panel content.

To highlight the output text, we use a FormattedText control which can be styled individually, either by using custom CSS or with HTML code. We add our custom CSS class (myCustomText) and add a theme-dependent CSS class to set the highlight color that is defined in the theme.

The actual color now depends on the selected theme which ensures that the color always fits to the theme and is semantically clear. For a complete list of the available CSS class names, see CSS Classes for Theme Parameters.