Simplify checkbox markup

Author: wimpyprogrammer

demo/index.html

@@ -60,9 +60,9 @@
 					</select>
 				</div>
 
-				<div class="form-group form-check">
-					<input type="checkbox" checked="checked" id="trim-whitespace" class="form-check-input">
-					<label for="trim-whitespace">
+				<div class="checkbox">
+					<label>
+						<input type="checkbox" checked="checked" class="form-check-input">
 						Trim whitespace surrounding each word/phrase
 					</label>
 				</div>