<head>
<style>
.cabecalho{
display:flex;
align-items: center;
justify-content: space-between;
}
.menu {
display:flex;
}
</style>
</head>
<body>
<header class="cabecalho">
<a class="logo" href="#">
<img src="img/logo.png">
</a>
<ul class="menu">
<li class="menu-item">Item 1 do menu</li>
<li class="menu-item">Item 2 do menu</li>
<li class="menu-item">Item 3 do menu</li>
<li class="menu-item">Item 4 do menu</li>
</ul>
</header>
</body>
