[bug] fix style for nested buttons in button group

Author: zombieFox

css/button.css

@@ -103,15 +103,21 @@ button [class*=" icon-"],
 border-radius:0;
 }
 
-.button-groupbutton:first-child,
-.button-group .button:first-child,
-.button-group .button-group-addon:first-child{
+.button-group>button:first-child,
+.button-group>.button:first-child{
 border-radius:var(--radius) 00var(--radius);
 }
 
-.button-groupbutton:last-child,
-.button-group .button:last-child,
-.button-group .button-group-addon:last-child{
+.button-group>button:last-child,
+.button-group>.button:last-child{
+border-radius:0var(--radius) var(--radius) 0;
+}
+
+.button-group.nested-button*:first-child .button{
+border-radius:var(--radius) 00var(--radius);
+}
+
+.button-group.nested-button*:last-child .button{
 border-radius:0var(--radius) var(--radius) 0;
 }
 

index.html

@@ -45,7 +45,7 @@
 </button>
 </div>
 <divclass="header-item header-edit-add">
-<divclass="button-group mb-0">
+<divclass="button-group nested-button mb-0">
 <divclass="checkbox-wrap">
 <inputid="control-edit" class="control-edit" type="checkbox" tabindex="1">
 <labelfor="control-edit" class="button button-checkbox">