Why do lines appear with rounded edges in mozilla, but as intended in Chrome and IE?

Question

css

This is an html template for EMAIL mailing list. Everything was done in the style of tables. without a framework.

<tr>
                                <td align="center" valign="top">
                                    
                                    <table  cellpadding="0" cellspacing="0" width="100%">
                                        <tr>
                                            <td align="center" valign="top">
                                                
                                                <table  cellpadding="0" cellspacing="0" width="600" class="flexibleContainer">
                                                    <tr>
                                                        <td align="center" valign="top" width="600" class="flexibleContainerCell bottomShim">

                                                          <hr class="polosa2"  align="center" color="#0b0b27" width="55%" size="20px"/>
                                                          <hr class="polosa3"  align="left" color="#ffda10" width="55%" size="20px"/>

                                                        </td>
                                                    </tr>
                                                </table>
                                                
                                            </td>
                                        </tr>
                                    </table>
                                    
                                </td>
                            </tr>

Answer 1

Zero out the HR styles. The browser itself can add standard styles