Hard lines/boxes exposed behind extreme box-shadow effect?

Question

How does one eliminate this effect so that it's just a clean box-shadow glow?

https://jsfiddle.net/stu9qjLp/2/

Code:

#test {
    border: 1px solid red;
    border-radius: 1px;
    width: 1px;
    height: 1px;
    box-shadow: 0 0 250px 125px red;
}

Answer 1

A radial gradient perhaps?

body {
  margin: 0;
  height: 100vh;
  background: #000;
}

body::before {
  content: '';
  position: absolute;
  height: 100%;
  width: 100%;
  background-image: radial-gradient(ellipse at center top, red, black 50%, black);
}