Create a file named style.css in static/css/ with this content to give your interface a dark, modern look:

style.css

@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@400;500;700&display=swap');

body {
    font-family: 'Roboto', sans-serif;
    background-color: #1e1e2f;
    color: #ffffff;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.chat-container {
    width: 100%;
    max-width: 600px;
    background-color: #2c2c3c;
    border-radius: 10px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.5);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.chat-header {
    background-color: #3c3c4f;
    padding: 20px;
    text-align: center;
}

.chat-header h1 {
    margin: 0;
    font-size: 24px;
    color: #ffffff;
}

.chat-box {
    flex-grow: 1;
    overflow-y: auto;
    padding: 20px;
    background-color: #2c2c3c;
}

.user-message {
    text-align: right;
    color: #00aaff;
    margin: 5px 0;
    font-weight: 500;
}

.ai-response {
    text-align: left;
    color: #00ff7f;
    margin: 5px 0;
    font-weight: 500;
}

.chat-input {
    display: flex;
    padding: 10px;
    background-color: #3c3c4f;
}

#user-input {
    flex-grow: 1;
    padding: 10px;
    border: 1px solid #444;
    border-radius: 5px;
    margin-right: 10px;
    background-color: #1e1e2f;
    color: #ffffff;
}

button {
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    background-color: #00aaff;
    color: white;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

button:hover {
    background-color: #0088cc;
}