styles.css

.content {
  background: #FFEEEE;
  background: -webkit-linear-gradient(to right, #DDEFBB, #FFEEEE);
  background: linear-gradient(to right, #DDEFBB, #FFEEEE);
}

.panel-header {
  color: black;
}

.panel {
  background: rgba(255, 255, 255, 0.5);
}