body {
  margin: 0;
  font-family: 'Arial Black', sans-serif;
  background-color: #000;
  color: #00FF00;
  text-align: center;
}
header {
  background-color: #333;
  padding: 20px;
}
.logo {
  height: 50px;
}
h1 {
  color: #00FF00;
}
.controls {
  margin: 20px;
}
select {
  padding: 10px;
  margin: 10px;
  font-weight: bold;
  font-size: 16px;
}
.preview-container {
  position: relative;
  display: inline-block;
}
#shirt-image {
  max-width: 400px;
  height: auto;
}
#logo-image {
  position: absolute;
  top: 25%;
  left: 50%;
  width: 150px;
  transform: translateX(-50%);
  opacity: 0.95;
}
footer {
  padding: 20px;
  color: #fff;
}