JSFiddle - React, Tailwind, and code Playground

HTML

<header>
  <img class="logo" src="svg/logo.svg">
</header>

<main>
  <!--
                  <div class="block1">
                    <img src="svg/block1.svg" class="block1_rectangle">
                  </div>
                  -->
  <div class="testblock">

  </div>
</main>

<footer>

</footer>

CSS

body {
  background-image: url(png/background1.png);
  background-repeat: no-repeat;
  background-position: center center;
  background-size: cover;
  margin: 0;

}

header {
  grid-area: header;
  font-family: Noto Sans;
  font-style: normal;
  font-weight: 500;
  color: white;
  height: 47px;
  width: 100%;
  background-color: #26529C;

}

.logo {
  margin-top: 10px;
  margin-left: 15px;
}

main {
  margin-top: 10px;
}

.testblock {
  width: 1000px;
  height: 1000px;
  background-color: black;
}