In testing Android mail app that's bringing in OWA, I keep seeing the button as 100% with no margin. What am I missing? The phone is LG G3 which says it displays at 523px. My button is 280px so why is it 100%?

<table width="100%" style="border-spacing:0;max-width:600px;">
      <tr bgcolor="#FFFFFF">
          <td style="padding:0;">
              <table width="100%" style="border-spacing:0;">
                  <tr>
                      <td height="15" style="padding:0;font-size:0;line-height:15px;">&nbsp;</td>
                  </tr>
                  <tr>
                      <td align="center" style="padding:0;">

                          <!--[if (gte mso 9)|(IE)]>
                          <table width="280">
                              <tr>
                                  <td valign="top" style="padding:0;">
                                  <![endif]-->

                          <table width="100%" style="Margin:0 15px;border-spacing:0;max-width:280px;">
                              <tr>
                                  <td width="100%" style="padding:15px 2px 17px 2px;border-radius:4px;background-color:#ff7e00;font-size:16px;line-height:22px;color:#ffffff;text-align:center;vertical-align:top;">
                                      <a href="{{#URL}}" title="linked to Call to action. " name="button" style="text-decoration:none;color:#ffffff;display:block;cursor:pointer;" target="_blank" tabindex="1">
                                          {{#CTA}}
                                      </a>
                                  </td>
                              </tr>
                          </table>

                                  <!--[if (gte mso 9)|(IE)]>
                                  </td>
                              </tr>
                          </table>
                          <![endif]-->

                      </td>
                  </tr>
                  <tr>
                      <td height="10" style="padding:0;font-size:0;line-height:10px;">&nbsp;</td>
                  </tr>
              </table>
          </td>
      </tr>
  </table>