body {
  background-color: lavender;
  font-family: arial, helvetica, verdana, sans-serif;
  font-weight: bolder;
  margin: 0;
}

nav {
  background-color: navy;
  height: 2.5em;
}

nav .show-menu:hover {
  background-color: lightskyblue;
  color: navy;
}

ul {
  list-style-type: none;
  margin-block-end: 0;
  margin-block-start: 0;
  padding: 0;
  position: absolute;
}

li {
  float: left;
}

li a {
  background: navy;
  color: white;
  display: block;
  line-height: 2.5em;
  min-width: 5em;
  text-align: center;
  text-decoration: none;
}

li:hover a {
  background: lightskyblue;
  box-shadow: 0 7px 15px -5px grey;
  color: navy;
}

li:hover ul a {
  background: blue;
  color: lightskyblue;
  height: 2.5em;
  line-height: 2.5em;
}

li:hover ul a:hover {
  background: lightcyan;
  color: blue;
}

li ul {
  display: none;
}

li ul li {
  display: block;
  margin-top: 1px;
  float: none;
}

li ul li a {
  width: auto;
  padding: 0 1em;
}

ul li a:hover+.hidden,
.hidden:hover {
  display: block;
}

.show-menu {
  color: white;
  cursor: pointer;
  padding: 1em 0;
  display: none;
}

input[type=checkbox] {
  display: none;
}

input[type=checkbox]:checked~#menu *:first-child {
  display: block;
}

@media screen and (max-width : 400px) {
  ul {
    position: static;
  }

  li {
    margin-top: 1px;
  }

  ul li,
  li a {
    display: block;
    float: none;
    width: 5em;
  }

  li:not(:first-child) a {
    box-shadow: 7px 7px 15px -5px grey;
    display: none;
  }

  .show-menu {
    display: block;
    float: right;
    padding: 0.7em 0.8em 0.6em 0.8em;
  }
}

header {
  background-image: url(eye.svg);
  background-origin: content-box;
  background-position: left;
  background-repeat: no-repeat;
  background-size: 2em;
  color: blue;
  cursor: default;
  font-size: 10vw;
  padding: 1.5em 0 2em 2em;
  position: fixed;
  text-indent: 2.5em;
  z-index: -1;
}