.button {
  background-color: #f5fffa; 
  color: black; 
  border: 3px solid grey;
  font-size: 16px;
  padding: 2px 18px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
  margin: 4px 2px;
  transition-duration: 0.4s;
  cursor: pointer;
  min-width: 10em;
}

.b_zurueck{border: 3px solid red;}

.button:hover {
  background-color: #4CAF50;
  color: white;
}
.button:disabled {background-color: Lightgray; color: red; border: Gainsboro; cursor: not-allowed;}
.kname {color: red; font: 18px Arial, sans-serif; font-weight: bold; padding: 2px 5px;}
.atxt {color: red; font: bold 16px Arial, sans-serif; padding: 2px 5px;}
.warn {border: 3px solid red; color: red; font: bold 16px Arial, sans-serif; padding: 2px 5px;}