@media (max-width: 800px){ .chat_content { position: fixed; top: 55px; bottom: 52px; left: 0; right: 0; height: auto; } .block_send{ position: fixed; bottom: 0; left: 0; right: 0; z-index: 10000; } .chat_cover{ position: fixed; top: 0; bottom: 0; left: 0; right: 0; } .chat_cover2{ background: #000000b8; position: fixed; top: 0; bottom: 0; left: 0; right: 0; } }