header {
  /*position: fixed;
  top: 0;*/
  
  width: 100%;
  background-color: #fff;
  z-index: 1000; /* Ensures the header is above other content */
  height: 50px;
}

nav.top-nav{
    width: 100%;
    display: flex;
    justify-content: space-between;
    padding: 0 1rem;
    background-color: #fff;
    height: 50px;
}

.left {
  padding-top: 0;
  width: 40%;
  text-align: left;
}
.center {
  width: 20%;
  text-align: center;
}
.right {
  width: 40%;
  text-align: right;
  padding-right: 3em;
}
#biologo, #navright  {
  padding-top: 7px;  
}
div#biologo img {height: 50px;}