Fix documentation and refactoring classes

src/index.html

@@ -14,7 +14,7 @@
 
       <button class="cg-dropdown cg-dropdown_one"></button>
       <input type="submit" form="data" value="Отправить" />
-      <!-- <button class="cg-dropdown cg-dropdown_three"></button> -->
+      <button class="cg-dropdown cg-dropdown_three"></button>
 
       <!-- <button class="cg-dropdown cg-dropdown_button" style="margin-top: 50px"></button> -->
     </div>