p {
  margin-bottom: 0;
}

.navbar {
  /*border-bottom: solid 2px linear-gradient(red, yellow, blue);*/
  position: fixed;
  width: 100%;
  /*margin-top: 20px;*/
  z-index: 1000;
  border-bottom: 4px solid transparent;
  border-image: linear-gradient(to right, red, blue) 1;
}

div {
}

#card {
  border: solid 1px lightgray;
  padding: 10px;
  border-left: solid 5px red;
}