Can’t record CSS

Hi !

I make custom CSS 2 month ago and now I can’t modify this CSS
When I want update modifications I have a blank page and nothing else !
Thanks

Hubert91

WordPress 4.7.3
Theme : Twenty seventeen
Custom CSS :

.tablepress .row-1 td {
	background-color: #F3F781;
}

.tablepress tbody td {
	font-family: Tahoma;
	font-size: 14.5px;
	color: #6E6E6E;
}

.tablepress {
	width: auto;
	margin: 0 auto 1em;
}