body {
  margin: 0;
  font-family: Arial, sans-serif;
  text-align: center;
}


nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: #07a330;
  padding: 10px 20px;
}

nav a {
  color: white;
  text-decoration: none;
  font-size: 16px;
}


h1 {
  margin-top: 30px;
}


.button {
  height: 40px;
  width: 40px;
  display: inline-block;
  margin: 10px;
  border-radius: 50%;
  border: 2px solid #000;
  cursor: pointer;
}

#grey {
  background: grey;
}
#white {
  background: white;
  border: 2px solid #ccc;
}
#blue {
  background: blue;
}
#yellow {
  background: yellow;
}
#random {
  height: 50px;
  width: 100%;               /* spans full width */
  max-width: 500px;          /* optional: align with circular buttons row */
  margin: 0 auto;            /* center horizontally */
  background-color: purple;
  display: flex;
  justify-content: center;
  align-items: center;
  color: white;
  font-weight: bold;
  cursor: pointer;
  border-radius: 8px;
  border: 2px solid #000;
  box-sizing: border-box;
  text-align: center;
  transition: background-color 0.3s;          
}