* {
    box-sizing: border-box;
}

body {
    margin: 0;
    background: #f5f5f5;
    font-family: Arial, sans-serif;
}

.app {
    max-width: 800px;
    margin: 50px auto;
    background: white;
    padding: 30px;
    border-radius: 15px;
}

h1 {
    margin-top: 0;
}

#chat {
    min-height: 400px;
    max-height: 600px;
    overflow-y: auto;
    margin-bottom: 20px;
}

.message {
    padding: 12px 16px;
    margin-bottom: 10px;
    border-radius: 10px;
}

.user {
    background: #e8f1ff;
}

.assistant {
    background: #eeeeee;
}

form {
    display: flex;
    gap: 10px;
}

input {
    flex: 1;
    padding: 15px;
    border: 1px solid #ccc;
    border-radius: 8px;
}

button {
    padding: 15px 25px;
    border: 0;
    border-radius: 8px;
    cursor: pointer;
}