<header class="site-header">
  <img src="<?php bloginfo('template_directory');?>/logo.svg" alt="Logo" class="site-logo">
  <div class="first-level-header">
    <h1>Name of website</h1>
  </div>
</header><!-- /site-header -->

h1 {
display: inline;
font-family: sans-serif;
color: blue;
}

img.site-logo {
  display: inline;
  padding-top: 10px;
  padding-left: 10px;
  width: 125px;
  height: 125px;
}