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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    background-color: #f5f5f5;
    color: #333;
}

.container {
    max-width: 1000px;
    margin: 2rem auto;
    padding: 0 1rem;
}

h1 {
    text-align: center;
    color: #2c3e50;
    margin-bottom: 2rem;
}

h2 {
    color: #34495e;
    margin-bottom: 1rem;
}

.upload-section, .modification-section, .download-section {
    background-color: white;
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    margin-bottom: 2rem;
}

input[type="file"] {
    width: 100%;
    padding: 0.5rem;
    border: 2px dashed #bdc3c7;
    border-radius: 4px;
    cursor: pointer;
}

.chat-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.chat-history {
    height: 300px;
    border: 1px solid #ddd;
    border-radius: 4px;
    padding: 1rem;
    overflow-y: auto;
    background-color: #f8f9fa;
}

.chat-input-container {
    display: flex;
    gap: 1rem;
}

textarea {
    flex: 1;
    min-height: 100px;
    padding: 0.5rem;
    border: 1px solid #ddd;
    border-radius: 4px;
    resize: vertical;
}

button {
    padding: 0.5rem 1rem;
    background-color: #3498db;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #2980b9;
}

button:disabled {
    background-color: #bdc3c7;
    cursor: not-allowed;
}

.message {
    margin-bottom: 0.5rem;
    padding: 0.5rem;
    border-radius: 4px;
}

.user-message {
    background-color: #e8f4fd;
    margin-left: 20%;
}

.system-message {
    background-color: #f0f0f0;
    margin-right: 20%;
}