override.css

@media screen {
    body.google-docs-utility-override .kix-tablerenderer-td,
    body.google-docs-utility-override .kix-tablerenderer-table {
        position: relative;
    }

    body.google-docs-utility-override .kix-tablerenderer-td:before,
    body.google-docs-utility-override .kix-tablerenderer-td:after,
    body.google-docs-utility-override .kix-tablerenderer-table:before,
    body.google-docs-utility-override .kix-tablerenderer-table:after {
        content: "\a0";
        display: block;
        position: absolute;
        pointer-events: none;
    }

    /* Cell right */
    body.google-docs-utility-override .kix-tablerenderer-td:before {
        right: -1px;
        bottom: 0;
        top: 0;
        border-right: 1px dashed #00000038;
    }

    /* Cell bottom */
    body.google-docs-utility-override .kix-tablerenderer-td:after {
        right: 0;
        left: 0;
        bottom: -1px;
        border-bottom: 1px dashed #00000038;
    }

    /* Table left */
    body.google-docs-utility-override .kix-tablerenderer-table:before {
        left: 0;
        bottom: 0;
        top: 0;
        border-left: 1px dashed #00000038;
    }

    /* Table top */
    body.google-docs-utility-override .kix-tablerenderer-table:after {
        left: 0;
        right: 0;
        top: 0;
        border-top: 1px dashed #00000038;
    }
}