html, body {
  height: 100%;
  margin: 0;
  padding: 0;
  overflow: hidden;
}
body {
  width: 100vw;
  height: 100vh;
  background: #0f2027; /* fallback for old browsers */
  background: linear-gradient(135deg, #2c5364, #203a43, #0f2027);
  position: relative;
}
#tech-bg {
  position: absolute;
  top: 0; left: 0;
  width: 100vw;
  height: 100vh;
  display: block;
  z-index: 1;
}
#center-img {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  max-width: 40vw;
  max-height: 40vh;
  width: auto;
  height: auto;
  z-index: 2;
  pointer-events: none;
}
@media (max-width: 600px) {
  #center-img {
    max-width: 80vw;
    max-height: 40vh;
  }
}