Glowing Gradient Border/glow_gradient_border.css
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: Arial, Helvetica, sans-serif;
}
body {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  min-height: 100vh;
  background-color: #010615;
}
.box {
  position: relative;
  width: 300px;
  height: 400px;
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: #060c21;
  margin: 40px auto;
}
.box:before {
  content: "";
  position: absolute;
  top: -2px;
  left: -2px;
  bottom: -2px;
  right: -2px;
  background-color: #fff;
  z-index: -1;
}
.box:after {
  content: "";
  position: absolute;
  top: -2px;
  left: -2px;
  bottom: -2px;
  right: -2px;
  background-color: #fff;
  z-index: -1;
  filter: blur(60px);
}
.box:nth-child(1):before,
.box:nth-child(1):after {
  background: linear-gradient(235deg, #89ff00, #010615, #00bcd4);
}
.box:nth-child(2):before,
.box:nth-child(2):after {
  background: linear-gradient(235deg, #ff005e, #010615, #fbff00);
}
.box:nth-child(3):before,
.box:nth-child(3):after {
  background: linear-gradient(250deg, #772aff, #010615, #2196f3);
}
.box .glass {
  position: absolute;
  top: 0;
  left: 0;
  width: 50%;
  height: 100%;
  display: block;
  background-color: rgba(255, 255, 255, 0.1);
}
.box .content {
  padding: 20px;
  color: white;
}
