html
{ 
}

body {
    color:blue;
    font-family: Arial;
    font-size: 20px;
    border-color: white;    
    background: url(fondo.jpg);
    border-radius: 24px;
    border: 2px solid white;
    box-shadow:inset 0 0 2px 2px white;
}

h1 {
    font-family: Times;
    text-decoration:underline;
    text-align: center;
}

h2 {
    font-family: sans-serif;
    text-align: center;
}

h3 {
    font-family: sans-serif;
    text-align: center;
}

.miriada {
    text-align: center;
}

#resultado, #marcoSumas {
  text-align: center;  
  font-size: 1.1em;
  font-style: bold;
  font-family: fantasy;
}

#botonWhile, #botonFor {
  border: 10px;
  padding: 5px;
}

#botonWhile:active, #botonFor:active {
  background-color: #A52A2A;
} 

iframe {
  width: 90%;
  height: 300px;
  border: 2px solid gray;  
}