<header>
  <div id="Menu">
    <ul class="MenuInner">    
      <li><a href="#">Главная</a></li>
      <li><a href="#">Кнопка</a></li>
      <li><a href="#">Кнопка</a></li>
      <li><a href="#">Кнопка</a></li>
      <li><a href="#">Кнопка</a></li>
    </ul>
  <a href="#" id="logo">Logo</a>
  </div>
  </header>

header {
    margin: 0 auto;
    width: 100%;
    box-shadow: 0 0 5px;
    position: fixed;
    z-index: 10;
    }
#logo {
   text-decoration: none;
   color: #d90368;
   font-weight: 700;
   font-style: italic;
   margin-right: 50px;
   font-size: 30px;   
   padding: 4px;
}
#Menu {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.MenuInner{
   margin: 0;
   padding: 0;
   list-style-type: none;
   background:green;
}
.MenuInner li{  
   margin: 0 10px 0 0;
   padding: 0;
   display: inline-block;
}
.MenuInner a {
 padding: 1em;
 }
 .MenuInner ul {
 padding: 1em;
 }
.MenuInner li span{
    display: block;
    font-size: 14px;
    color: rgba(255, 255, 255, 0.50);
}
.MenuInner li a{
    margin-left: 40px;           
    text-transform: uppercase;
    font-weight: bold;
    cursor: pointer;
    text-decoration: none;
    color: black;   
}
.MenuInner li a:hover{
    color: gray; /* цвет кнопок при наведении */
    transition: 1s ;
}