Please specify styles using CSS classes and div.

.box {
  background-color: red;
  color: white;
  border: 2px solid black;
}

Usage:

<div class="box">
  <h2>Paris</h2>
  <p>Paris is the capital of France.</p>
</div>

• You can use the same header for all pages.
  

• the "dikenli" and "dikensiz" pages layouts are not correct

• other pages are not looking good and have no CSS on them

index.html

• fix the style.css source path as : href="./style.css". Even you can create a style folder for it.
• use margin and padding to spacing out.
• Buttons are not working, add some functionality for it.
• "İletişim"