body {
  font-family: Arial, sans-serif;
  background: #f9f9f9;
  margin: 0;
  padding: 10px;
}

.card {
  max-width: 600px;
  width: 100%;
  background: #fff;
  padding: 10px;
  margin: auto;
  border: 2px solid #000;
  box-sizing: border-box;
  font-size:12px;
}

input[type="text"] {
  width: 100%;
  padding: 10px;
  font-size: 16px;
  box-sizing: border-box;
}

button {
  background: #000;
  color: white;
  padding: 12px 20px;
  font-size: 16px;
  border: none;
  width: 100%;
  cursor: pointer;
}

@media screen and (max-width: 600px) {
  .card {
    border-width: 1px;
    padding: 15px;
  }

  input[type="text"] {
    font-size: 14px;
  }

  button {
    font-size: 14px;
  }
}