Unity style sheet (USS) Selectors are queries into the element hierarchy. They look like this in USS:
.my-button {
background-color: blue;
}
The above USS Selector looks for all elements that have the class or tag .my-button
and any matching elements will get the background color blue.
You can use USS Selectors inside StyleSheets to share styles across elements and UI Documents (UXML). You can create a new USS Selectors through the Add new selector… field at the top of the StyleSheets pane.
When you have the Add new selector… field in focus, a USS Selector syntax reference appears on top of the Viewport, as shown in the image below:
To cut/copy/paste/delete
one or more USS Selectors in the StyleSheets pane, select the group, right-click, and choose the desired action.
When you copy a USS Selector in the StyleSheets pane, what actually gets copied to the copy/paste buffer is the USS text representation of the USS Selector. This means you can paste it in a text editor directly or, the opposite, copy some USS text and paste it in the UI Builder.
It’s recommended to use style classes to match elements instead of their C# type or name attribute. The image below displays the StyleSheets pane containing USS style class labels:
You can have a USS Selector match an element by adding a style class (or “tag”) used in the USS Selector to the element. You can add a style class to an element in two ways:
To see what style classes are already applied to an element, look at the yellow style class labels in the StyleSheet section of the Inspector:
You can double-click on a yellow style class labels to jump to a USS Selector that uses it as its only query, if one exists in the attached StyleSheets.
If a yellow style class label appears faded, the UI Builder couldn’t find a USS selector in the attached StyleSheets that contains this class in its query. You can double-click on a faded yellow class label to create a new USS selector in the Active StyleSheet that looks for this style class.