Universal selectors

* { style properties }

* [lang^="en"] {
  color: green;
}
*.warning {
  color: red;
}
*#maincontent {
  border: 1px solid blue;
}
.floating {
  float: left;
}
/* automatically clear the next sibling after a floating element */
.floating + * {
  clear: left;
}

<p class="warning">
  <span lang="en-us">A green span</span> in a red paragraph.
</p>
<p id="maincontent" lang="en-gb">
  <span class="warning">A red span</span> in a green paragraph.
</p>

@namespace example url("https://www.example.com/");
example|* {
  color: blue;
}