body {
  background: #101820;
  color: #00ff90;
  font-family: ariel;
  padding: 2rem;
}
.intro {
  background: #101820;  
  color: #00ff90;
  font-size: 1rem;
  padding: 5px;
  border-radius: 50px;
  margin: 5px;
  box-shadow: 0 0 100px black;
  margin-top: 0.5rem;
  margin-bottom: 0.5rem;
  white-space: pre;
}
 .door {
  background: red;  
  color: white;
  font-size: 2rem;
  padding: 5px;
  border-radius: 50px;
  margin: 5px;
  box-shadow: 0 0 100px white;
  margin-top: 0.5rem;
  margin-bottom: 0.5rem;
  white-space: pre;
  text-decoration: white dotted underline;
}
 .front {
  background: blue;
  color: black; 
}
  h1, h2, h3 {
  text-align: center;
}
  .container {
  max-width: 900px;
  padding: 40px;
  margin: 0 auto;
}
 .card {
 background: black;
 color: white;
 padding: 10px;
 border-radius: 50px;
 margin: 10px;
 box-shadow: 0 0 10px white;
}
 .cardb {
 background: red;
 color: white;
 padding: 10px;
 border-radius: 50px;
 margin: 10px;
 box-shadow: 0 0 10px green;
}
 .grid {
 display: grid;
 grid-template-columns: repeat(3, 1fr);
 gap: 5px;
}
 nav {
 display: flex;
 justify-content: center;
 gap: 50px;
}
 hr {
 border: none;
 height: 10px;
 background: #00ff90;
}
 .button {
 background: #00ff90;
 padding: 15px 30px;
 border-radius: 20px;
 box-shadow: 0 0 20px #00ff90;
}
 .buttonb {
 background: red;
 color: white;
 padding: 15px 30px;
 border-radius: 20px;
 box-shadow: 0 0 20px #00ff90;
}
 .cardc {
 background: white;
 color: black;
 padding: 15px 30px;
 border-radius: 20px;
 box-shadow: 0 0 20px #00ff90;
} 
 .cardd {
 background: blue;
 color: white;
 padding: 15px 30px;
 border-radius: 20px;
 box-shadow: 0 0 20px #00ff90;
}