CSS

 body
{
    margin:0px;
    padding:0px;
    width:100%;
    height:100vh;
    
}
*
{
    padding:0px;
    margin:0px;
}

.parent{width:100%; height:100vh; position:absolute; background-image: linear-gradient(  #a2d9ce  , #117a65 ) ;}
.child{width:90%; display:flex; height:70vh; position:relative; top:50%; left:50%; transform:translate(-50%,-50%);}
.col-1{border-radius:10px 0px 0px 10px; width:40%; height:100%; box-shadow:10px 10px 10px black; border-top:1px solid white; border-left:1px solid white;}
.col-2{ border-radius:0px 10px 10px 0px; width:59%; margin-left:1%; height:100%; box-shadow:10px 10px 10px black; border-top:1px solid white; border-left:1px solid white;}
hr{width:80%;}
h3{color:white; font-family:sans-serif;}
table{width:98%; margin:10px;}



.tb{width:65%; border-radius:6px; padding:2px;}
.tb1{width:90%; border-radius:6px; padding:2px;}



.btn{padding:5px; transition:0.5s; width:100px; height:30px; float:right; border-radius:10px; border:none; color:#566573; background-color:#ABEBC6;}
.btndiv{width:120px; height:30px; transition:1s; background-color:#0000;  border-radius:10px; border:1PX SOLID WHITE; }
.btn:hover{  color:black; float:left; font-weight:bold;}
.btn:hover .btndiv{background-color:#ABEBC6;}


aspx

<form id="form1" runat="server">
    <div class="parent">
    <div class="child">
        <div class="col-1">
        <center><h3>PURCHASE ITEM </h3><hr /></center>
            <table>
                <tr>
                    <td style="width: 105px; height: 35px;">
                        BILL NO:</td>
                    <td style="width: 100px; height: 35px;">
                        <asp:Label ID="billno" runat="server" Text="bill"></asp:Label></td>
                    <td style="width: 100px; height: 35px;">
                        DATE:</td>
                    <td style="width: 100px; height: 35px;">
                        <asp:TextBox ID="tbdate" class="tb" runat="server"></asp:TextBox></td>
                </tr>
                <tr>
                    <td style="width: 105px; height: 35px;">
                        &nbsp;NAME:</td>
                    <td colspan="3" style="height: 35px">
                        <asp:TextBox class="tb1" ID="tbname" runat="server"></asp:TextBox></td>
                </tr>
                <tr>
                    <td style="width: 105px; height: 25px;">
                        ADDRESS:</td>
                    <td style="width: 100px; height: 25px;">
                        <asp:TextBox class="tb1" ID="tbadd" runat="server"></asp:TextBox></td>
                    <td style="width: 100px; height: 25px;">
                        NUMBER:</td>
                    <td style="width: 100px; height: 25px;">
                        <asp:TextBox ID="tbnum" class="tb1" runat="server"></asp:TextBox></td>
                </tr>
                <tr>
                    <td style="height: 8px;" colspan="4"><center><hr /></center>
                    </td>
                </tr>
                <tr>
                    <td colspan="1" style="height: 26px; width: 105px;">
                        ITEM NAME :</td>
                    <td colspan="3" style="height: 26px">
                        <asp:TextBox ID="tbitemname" class="tb1" runat="server"></asp:TextBox></td>
                </tr>
                <tr>
                    <td style="width: 105px; height: 30px;">
                        QTY:</td>
                    <td style="width: 100px; height: 30px;">
                        <asp:TextBox ID="tbqty" class="tb" runat="server">1</asp:TextBox></td>
                    <td style="width: 100px; height: 30px;">
                        UNIT :</td>
                    <td style="width: 100px; height: 30px;">
                        <asp:DropDownList ID="DropDownList1" runat="server">
                            <asp:ListItem>KG</asp:ListItem>
                            <asp:ListItem>GR</asp:ListItem>
                            <asp:ListItem>PIEce</asp:ListItem>
                        </asp:DropDownList></td>
                </tr>
                <tr>
                    <td style="width: 105px; height: 30px;">
                        PRICE:
                    </td>
                    <td style="width: 100px; height: 30px;">
                        <asp:TextBox ID="tbprice" class="tb" runat="server"></asp:TextBox></td>
                    <td style="width: 100px; height: 30px;">
                        DISCOUNT :</td>
                    <td style="width: 100px; height: 30px;">
                        <asp:DropDownList ID="DropDownList2" runat="server">
                            <asp:ListItem Value="0">0%</asp:ListItem>
                            <asp:ListItem Value="5">5%</asp:ListItem>
                            <asp:ListItem Value="3">3%</asp:ListItem>
                            <asp:ListItem Value="10">10%</asp:ListItem>
                        </asp:DropDownList></td>
                </tr>
                <tr>
                    <td style="width: 105px; height: 24px;">
                        AMOUNT :</td>
                    <td style="width: 100px; height: 24px;">
                    </td>
                    <td style="width: 100px; height: 24px;">
                        DISC AMT:</td>
                    <td style="width: 100px; height: 24px;">
                    </td>
                </tr>
                <tr>
                    <td style="width: 105px; height: 10px;">
                        NET AMT:</td>
                    <td style="width: 100px; height: 10px;">
                    </td>
                    <td style="width: 100px; height: 10px;">
                    </td>
                    <td style="width: 100px; height: 10px;">
                    </td>
                </tr>
                <tr>
                    <td style="width: 105px; height: 13px;">
                        PAYMENT:</td>
                    <td style="height: 13px;" colspan="3">
                        <asp:RadioButtonList ID="RadioButtonList1" runat="server" RepeatDirection="Horizontal">
                            <asp:ListItem Selected="True">CASH</asp:ListItem>
                            <asp:ListItem>ONLINE</asp:ListItem>
                            <asp:ListItem>CHEACK</asp:ListItem>
                        </asp:RadioButtonList></td>
                </tr>
                <tr>
                   
                    <td colspan="2" style="height: 8px"><center>
                     <div class="btndiv"><asp:Button class="btn" ID="btninsert" runat="server" Text="INSERT" /></div>
                        </center>
                    </td>
                    <td colspan="2" style="height: 8px"><center>
                    <div class="btndiv">
                        <asp:Button class="btn" ID="btnupdate" runat="server" Text="UPDATE" />
                        </div></center>
                </td>
                </tr>
                <tr>
                   
                    <td colspan="2" style="height: 12px"><center>
                    <div class="btndiv"><asp:Button class="btn" ID="btndelete" runat="server" Text="DELETE" /></div></center>
                    </td>
                    <td colspan="2" style="height: 12px"><center>
                    <div class="btndiv"><asp:Button class="btn" ID="btnclear" runat="server" Text="CLEAR" /></div></center>
                    </td>
                </tr>
                            </table>
        <br>
        </div>
        

        <div class="col-2">
        <center><h3>ITEMs LIST </h3><hr /></center>
        
        <asp:GridView ID="GridView1" runat="server">
            <Columns>
                <asp:BoundField DataField="SELECT" HeaderText="OPTIONS" SortExpression="SELECT" />
            </Columns>
                </asp:GridView>
        </div>
    </div>
    </div>
</form>

.cs

tbdate.Text = DateTime.Now.ToString("yyyy-MM-dd");