[EuiPanel] Fix selector for button element styling

CHANGELOG.md

@@ -1,6 +1,8 @@
 ## [`master`](https://github.com/elastic/eui/tree/master)
 
-No public interface changes since `32.0.0`.
+**Bug fixes**
+
+- Fixed block style of `EuiPanel` when rendered as a `<button>` ([#4681](https://github.com/elastic/eui/pull/4681))
 
 ## [`32.0.0`](https://github.com/elastic/eui/tree/v32.0.0)
 

src/global_styling/mixins/_panel.scss

@@ -25,7 +25,7 @@
         // transition the shadow
         transition: all $euiAnimSpeedFast $euiAnimSlightResistance;
 
-        button#{&} {
+        &:enabled { // This is a good selector for buttons since it doesn't exist on divs
           // in case of button wrapper which inherently is inline-block and no width
           display: block;
           width: 100%;

src/themes/eui-amsterdam/global_styling/mixins/_panel.scss

@@ -22,7 +22,7 @@
         // transition the shadow
         transition: all $euiAnimSpeedFast $euiAnimSlightResistance;
 
-        button#{&} {
+        &:enabled { // This is a good selector for buttons since it doesn't exist on divs
           // in case of button wrapper which inherently is inline-block and no width
           display: block;
           width: 100%;