you have set a property:

 background: linear-gradient(90deg, #72C6EF 0%, #004E8F 100%); //Esta propiedad lo que hace es hacer ese degrade azul que vez.

Instead, you should replace the background color of your header with the color of your logo in this case white.

HTML

 <header> <nav class="navbar navbar-light bg-light"> <div class="container"> <a class="navbar-brand" href="#"> <img src="./img/Logo.png" height="100"/> </a> </div> </nav> </header>

CSS

 *{ box-sizing: border-box; margin: 0; padding: 0; background: #ffffff; } header{ display: flex; justify-content: space-between; align-items: center; padding: 10px 10%; background: #ffffff; }

With this the background of your header would have to be white (of the color of your logo). Although it is not the most optimal, I recommend you make your logo .png so that you do not have to place the background of the header in the same color as the background of your logo.