Test Page

Test1

Test2

Test3

Test4

<button class="tablink" onclick="openCity('London', this, 'red')" id="defaultOpen">London</button> <button class="tablink" onclick="openCity('Paris', this, 'green')">Paris</button> <button class="tablink" onclick="openCity('Tokyo', this, 'blue')">Tokyo</button> <button class="tablink" onclick="openCity('Oslo', this, 'orange')">Oslo</button>