* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: Arial, sans-serif; background: #f0f0f0; }
#chat-container { max-width: 800px; margin: 20px auto; background: #fff; border-radius: 8px; box-shadow: 0 2px 10px rgba(0,0,0,0.1); display: flex; flex-direction: column; height: 90vh; }
#chat-header { background: #007bff; color: #fff; padding: 15px; border-radius: 8px 8px 0 0; display: flex; justify-content: space-between; }
#chat-messages { flex: 1; padding: 15px; overflow-y: auto; background: #f9f9f9; }
.message { margin-bottom: 10px; padding: 8px 12px; border-radius: 18px; max-width: 70%; word-wrap: break-word; }
.message.visitor { background: #e1f3fb; align-self: flex-start; }
.message.user { background: #dcf8c6; align-self: flex-end; margin-left: auto; }
.message img, .message video { max-width: 200px; cursor: pointer; border-radius: 5px; }
#chat-input-area { display: flex; padding: 10px; border-top: 1px solid #ddd; background: #fff; border-radius: 0 0 8px 8px; }
#message-input { flex: 1; padding: 10px; border: 1px solid #ccc; border-radius: 20px; resize: none; height: 50px; }
#send-btn, #upload-btn { margin-left: 10px; padding: 10px 20px; background: #007bff; color: #fff; border: none; border-radius: 20px; cursor: pointer; }
#send-btn:hover, #upload-btn:hover { background: #0056b3; }
#file-input { display: none; }
.lightbox { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.8); display: flex; justify-content: center; align-items: center; z-index: 1000; }
.lightbox img, .lightbox video { max-width: 90%; max-height: 90%; }