*{
  margin:0;
  padding:0;
  box-sizing:border-box;
}

body{
  font-family:Arial, sans-serif;
  background:#0f172a;
  display:flex;
  justify-content:center;
  align-items:center;
  height:100vh;
}

.container{
  width:400px;
  height:650px;
  background:white;
  border-radius:20px;
  overflow:hidden;
  box-shadow:0 0 20px rgba(0,0,0,0.3);
}

.header{
  background:#2563eb;
  color:white;
  padding:20px;
  text-align:center;
}

.chat-box{
  height:500px;
  overflow-y:auto;
  padding:15px;
  background:#f1f5f9;
}

.message{
  padding:12px;
  border-radius:12px;
  margin-bottom:15px;
  max-width:80%;
  line-height:1.5;
}

.user{
  background:#2563eb;
  color:white;
  margin-left:auto;
}

.bot{
  background:white;
  border:1px solid #ddd;
}

.input-area{
  display:flex;
  padding:15px;
  border-top:1px solid #ddd;
}

input{
  flex:1;
}