body {
  font-family: sans-serif;
  max-width: 700px;
  margin: 40px auto;
  padding: 0 15px;
}

h1 {
  margin-bottom: 20px;
}
#online {
  color: #555;
  font-size: 13px;
  margin-bottom: 8px;
}

#messages {
  border: 1px solid #ccc;
  height: 500px;
  padding: 15px;
  margin-bottom: 15px;
  overflow-y: auto;
  box-sizing: border-box;
}

.message {
  margin-bottom: 12px;
  overflow-wrap: anywhere;
}

.message-name {
  font-weight: bold;
}

.message-id {
  color: #777;
  font-size: 12px;
  margin-right: 4px;
}

.message-time {
  color: #888;
  font-size: 12px;
  margin-left: 4px;
}

#chat-form {
  display: flex;
  gap: 5px;
  align-items: center;
}

#username {
  width: 100px;
}

#message {
  flex: 1;
  min-width: 0;
}

input,
button {
  padding: 8px;
  box-sizing: border-box;
}

input[type="color"] {
  width: 40px;
  height: 36px;
  padding: 2px;
  cursor: pointer;
}

#status {
  color: #888;
  font-size: 13px;
}


/* スマホ用 */

@media (max-width: 600px) {
  body {
    margin: 20px auto;
    padding: 0 10px;
  }

  #messages {
    height: 400px;
    padding: 10px;
  }

  #chat-form {
    flex-wrap: wrap;
  }

  #username {
    width: 100px;
  }

  #message {
    width: calc(100% - 145px);
  }

  button {
    width: 50px;
  }

  .message-time {
    font-size: 11px;
  }

  .message-id {
    font-size: 11px;
  }
}