html, body {
  margin: 0;
}

body {
  display: flex;
  justify-content: center;
  background-color: rgb(20,20,20);
  width: 100vw;
  height: 100vh;
}

.main-image {
  max-height: 100vh;
  max-width: 100vw;
  object-fit: contain;
}

.caption {
  position: absolute;
  font-family: Helvetica;
  background-color: rgb(20,20,20);
  opacity: 0.8;
  color: white;
  font-size: 2em;
  width: 50%;
  left: 0;
  text-align: center;
  padding: 1em 25%;
  bottom: 10%;
}

html, body {
  margin: 0;
}

body {
  display: flex;
  justify-content: center;
  background-color: rgb(20,20,20);
  width: 100vw;
  height: 100vh;
}

.main-image {
  max-height: 100vh;
  max-width: 100vw;
  object-fit: contain;
}

.caption {
  position: absolute;
  font-family: Helvetica;
  background-color: rgb(20,20,20);
  opacity: 0.6;
  color: white;
  font-size: 2em;
  width: 96%;
  left: 0;
  text-align: center;
  padding: 2%;
  bottom: 10%;
}

Adjust the padding and opacity of caption
Adjust the padding and opacity of caption
