/* Base styles */
body {
  text-align: center;
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
}

/* Container for buttons */
.btn-container {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  max-width: 480px;
  margin: 0 auto;
  gap: 1rem;
}

/* Each line of buttons */
.line-one,
.line-two {
  display: flex;
  justify-content: center;
  gap: 1rem;
  width: 100%;
}

/* Buttons */
.btn {
  flex: 1 1 40%;
  max-width: 200px;
  height: 150px;
  border: 10px solid black;
  border-radius: 20%;
  margin: 0;
  font-size: 2rem;
  line-height: 150px;
  color: black;
  cursor: pointer;
  user-select: none;
  transition: background-color 0.3s ease;
}

/* Colors */
.red {
  background-color: lightcoral;
}

.yellow {
  background-color: lightgreen;
}

.green {
  background-color: lightseagreen;
}

.blue {
  background-color: lightblue;
}

/* Flash effect */
.flash {
  background-color: white !important;
}

.userflash {
  background-color: green !important;
}

/* Responsive adjustments */
@media (max-width: 600px) {
  .btn-container {
    max-width: 100%;
    padding: 0 1rem;
  }

  .btn {
    flex-basis: 45%;
    height: 120px;
    font-size: 1.5rem;
    line-height: 120px;
  }
}

@media (max-width: 400px) {
  .btn {
    flex-basis: 90%;
    height: 100px;
    font-size: 1.2rem;
    line-height: 100px;
  }
}