body {
    font-family: sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f9;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}
#app {
    width: 100%;
    max-width: 600px;
    background-color: white;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
    border-radius: 8px;
    overflow: hidden;
}
h1 {
    background-color: #4CAF50;
    color: white;
    padding: 15px;
    margin: 0;
    font-size: 1.2em;
}
#chat-window {
    height: 400px;
    padding: 15px;
    overflow-y: auto;
    border-bottom: 1px solid #eee;
}
.message {
    padding: 8px 12px;
    margin-bottom: 10px;
    border-radius: 15px;
    max-width: 80%;
}
.system {
    background-color: #e0f7fa;
    color: #00796b;
    text-align: center;
}
#input-area {
    display: flex;
    padding: 10px;
    gap: 10px;
}
#chat-input {
    flex-grow: 1;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 5px;
}
#send-button {
    padding: 10px 15px;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}
#lecture-upload {
    padding: 10px;
}