*{
    margin:0;
    padding:0;
    box-sizing:border-box;
    font-family:Arial, Helvetica, sans-serif;
}

html,body{
    width:100%;
    height:100%;
}

body{
    min-height:100vh;
    display:flex;
    justify-content:center;
    align-items:center;
    background:url("https://images.unsplash.com/photo-1677442136019-21780ecad995?auto=format&fit=crop&w=1400&q=80") no-repeat center center;
    background-size:cover;
    background-attachment:fixed;
}

/* chatbot in exact center */
.chat-container{
    width:520px;
    height:720px;
    position:absolute;
    top:50%;
    left:50%;
    transform:translate(-50%,-50%);
    
    background:rgba(255,255,255,0.96);
    border-radius:24px;
    overflow:hidden;
    display:flex;
    flex-direction:column;
    box-shadow:0 20px 45px rgba(0,0,0,0.35);
}

.header{
    background:#2563eb;
    color:white;
    text-align:center;
    padding:18px;
    font-size:24px;
    font-weight:bold;
}

.chat-box{
    flex:1;
    padding:15px;
    overflow-y:auto;
    background:#f8fafc;
}

.bot-message,
.user-message{
    padding:12px 15px;
    margin:10px 0;
    border-radius:16px;
    max-width:80%;
    line-height:1.4;
}

.bot-message{
    background:#e5e7eb;
}

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

.input-area{
    display:flex;
    gap:10px;
    padding:10px;
    background:white;
}

input{
    flex:1;
    padding:12px;
    border:1px solid #ccc;
    border-radius:10px;
    outline:none;
}

button{
    padding:12px 18px;
    border:none;
    background:#2563eb;
    color:white;
    border-radius:10px;
    cursor:pointer;
}

button:hover{
    background:#1d4ed8;
}