遮罩层背景图片样式：
background-color: rgba(0,0,0,.1);
background-image: url(data:image/gif;base64,R0lGODlhAwADAIABAP///////yH/C1hNUCBEYXRhWE1QPD94cGFja2V0IGJlZ2luPSLvu78iIGlkPSJXNU0wTXBDZWhpSHpyZVN6TlRjemtjOWQiPz4gPHg6eG1wbWV0YSB4bWxuczp4PSJhZG9iZTpuczptZXRhLyIgeDp4bXB0az0iQWRvYmUgWE1QIENvcmUgNS41LWMwMTQgNzkuMTUxNDgxLCAyMDEzLzAzLzEzLTEyOjA5OjE1ICAgICAgICAiPiA8cmRmOlJERiB4bWxuczpyZGY9Imh0dHA6Ly93d3cudzMub3JnLzE5OTkvMDIvMjItcmRmLXN5bnRheC1ucyMiPiA8cmRmOkRlc2NyaXB0aW9uIHJkZjphYm91dD0iIiB4bWxuczp4bXA9Imh0dHA6Ly9ucy5hZG9iZS5jb20veGFwLzEuMC8iIHhtbG5zOnhtcE1NPSJodHRwOi8vbnMuYWRvYmUuY29tL3hhcC8xLjAvbW0vIiB4bWxuczpzdFJlZj0iaHR0cDovL25zLmFkb2JlLmNvbS94YXAvMS4wL3NUeXBlL1Jlc291cmNlUmVmIyIgeG1wOkNyZWF0b3JUb29sPSJBZG9iZSBQaG90b3Nob3AgQ0MgKE1hY2ludG9zaCkiIHhtcE1NOkluc3RhbmNlSUQ9InhtcC5paWQ6NEFBQkJBQjg1QzA0MTFFNEJDNzU5NkUxMUNCNDlFNkIiIHhtcE1NOkRvY3VtZW50SUQ9InhtcC5kaWQ6NEFBQkJBQjk1QzA0MTFFNEJDNzU5NkUxMUNCNDlFNkIiPiA8eG1wTU06RGVyaXZlZEZyb20gc3RSZWY6aW5zdGFuY2VJRD0ieG1wLmlpZDo2MUI1NjcwOTVCQTQxMUU0QkM3NTk2RTExQ0I0OUU2QiIgc3RSZWY6ZG9jdW1lbnRJRD0ieG1wLmRpZDo2MUI1NjcwQTVCQTQxMUU0QkM3NTk2RTExQ0I0OUU2QiIvPiA8L3JkZjpEZXNjcmlwdGlvbj4gPC9yZGY6UkRGPiA8L3g6eG1wbWV0YT4gPD94cGFja2V0IGVuZD0iciI/PgH//v38+/r5+Pf29fTz8vHw7+7t7Ovq6ejn5uXk4+Lh4N/e3dzb2tnY19bV1NPS0dDPzs3My8rJyMfGxcTDwsHAv769vLu6ubi3trW0s7KxsK+urayrqqmop6alpKOioaCfnp2cm5qZmJeWlZSTkpGQj46NjIuKiYiHhoWEg4KBgH9+fXx7enl4d3Z1dHNycXBvbm1sa2ppaGdmZWRjYmFgX15dXFtaWVhXVlVUU1JRUE9OTUxLSklIR0ZFRENCQUA/Pj08Ozo5ODc2NTQzMjEwLy4tLCsqKSgnJiUkIyIhIB8eHRwbGhkYFxYVFBMSERAPDg0MCwoJCAcGBQQDAgEAACH5BAEAAAEALAAAAAADAAMAAAIEBGKhUQA7)