* {
  margin: 0;
}

h1,
h2,
p,
nav > * {
  padding: 15px 20px;
}

nav span{
  background:azure;
  box-shadow: 0 5px 0 0 azure;
}

section {
  height: 100vh;
}

header,
section:nth-of-type(even) {
  background-color: lightyellow;
}
section:nth-of-type(odd) {
  background-color: azure;
}

header,
nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

#galeria{
  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  img{
    width: 200px;
    margin:5px
  }
}