You can have this css (on page or file) after the grid css inclusion. (where list1 is grid id)

You can add following CSS code to show vertial lines in datagrid.

<style>
.ui-jqgrid table tr.ui-row-ltr td[role="gridcell"] { border-right-style:solid !important; }
.ui-jqgrid table tr.ui-row-rtl td[role="gridcell"] { border-left-style:solid !important; }
</style>

I createa a css file and included at the top of my page. That css file contains following code. All code works except this vertial lines one.

/* alternate row color */
/* .myAltRowClass { background-color: #F1F1F1 !important; background-image: url(”) !important; } */
.myAltRowClass { background-color: #ecece5 !important; background-image: url(”) !important; }
/* adjust highlight row option */
.ui-state-highlight, .ui-widget-content .ui-state-highlight, .ui-widget-header .ui-state-highlight
{
    background:rgba(240, 173, 78, 0.815) url(“images/ui-bg_flat_55_fbec88_40x100.png”) repeat-x scroll 50% 50% !important;
}
.ui-state-hover
{
    font-weight: bolder;
    color: #404040 !important;
}
.ui-jqgrid table tr.ui-row-ltr td[role=”gridcell”] { border-right-style:solid !important; }
.ui-jqgrid table tr.ui-row-rtl td[role=”gridcell”] { border-left-style:solid !important; }

This file should be after the grid css files. Otherwise grid will override the changes. Also check via browser debugger if these css changed are included in the cell TD.