account-financial-reporting/customer_outstanding_statement/static/src/less/layout_statement.less

@odoo-color-silver-darker: #d9d7d7;
@gray-lighter-darker: @odoo-color-silver-darker;

.table-statement {
    .amount {
        text-align: right !important;
        width: 14%  //spread 7 columns evenly
    }
    thead {
        border-bottom: solid; // required for clean layout
        tr th:first-child {
            width: auto !important; // required for clean layout
            }
        tr th:last-child {
            width: 16% !important; // required for boxed layout
            }
    }
}

.statement-blocked {
    background-color: @gray-lighter-darker !important;
    td:last-child {
        background-color: @gray-lighter-darker !important;
    }
}