Alwaysdisplay grid lines in DataGridView

<asp:gridview bordercolor="Gray" borderstyle="Solid" forecolor="Transparent" gridlines="Horizontal" xmlns:asp="#unknown" /> 

<rowstyle cssclass="gridViewRow" />

.gridViewRow{
border-bottom-color: gray;
background-color: white;
border-bottom-style: solid;
font-size: 11pt;
color: black;
font-family: Tahoma;
}