body {
  font-family: "Hiragino Kaku Gothic ProN", "メイリオ", sans-serif;
  background: #f0f2f5;
  margin: 0;
  padding: 0;
}

h2 {
  text-align: center;
  padding: 10px;
  margin: 0;
  background: #4caf50;
  color: white;
}

form {
  margin: 15px;
}

input, button {
  padding: 8px;
  margin: 3px;
  font-size: 14px;
}

.chat-box {
  height: 70vh;
  overflow-y: auto;
  padding: 15px;
  display: flex;
  flex-direction: column;
}

.message {
  display: flex;
  margin: 5px 0;
}

.message.me {
  justify-content: flex-end;
}

.message.other {
  justify-content: flex-start;
}

.bubble {
  max-width: 60%;
  padding: 10px 14px;
  border-radius: 15px;
  position: relative;
  font-size: 14px;
  background: #e5e5ea;
}

.message.me .bubble {
  background: #4caf50;
  color: white;
  border-bottom-right-radius: 0;
}

.message.other .bubble {
  background: #fff;
  border: 1px solid #ddd;
  border-bottom-left-radius: 0;
}

.time {
  display: block;
  font-size: 10px;
  color: gray;
  margin-top: 4px;
  text-align: right;
}