body {
  background: #fff;
}

#nav {
  background: #4f5b68;
  height: 100%;
  width: 300px;
  position: fixed;
  left: 0;
  top: 0;
  bottom: 0;
}

#header {
  background: #4f5b68;
  width: calc(100% - 300px);
  margin-left: 300px;
  justify-content: space-between;
  align-items: center;
  position: fixed;
  top: 0;
  z-index: 10;
}

#main {
  width: calc(100% - 300px);
  margin-left: 300px;
  justify-content: center;
  margin-top: 3rem;
}

form {
  width: 100%;
  max-width: 800px;
}

input[type="text"],
input[type="password"],
textarea.form-control {
  background: #f5f5f9;
}
select.form-control {
  background: #f5f5f9;
}

.input-group-append button:first-of-type {
  margin-right: 2px;
}

.nav a {
 color: #4f5b68;
}
#main .nav a.active {
 color: #3a444e;
}

@media(max-width: 990px){
  #nav {
    width: 50px;
  }
  #main, #header {
    width: calc(100% - 50px);
    margin-left: 50px;
  }
}