flexbox woes

IE text flow problem

HTML

<div class="flexbody">
  <div class="h1">Glossary</div>
  <div class="h2">A</div>
  <div class="h3">Aardvark</div>
  <p class="finalsib">Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
    in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
  <div class="h3">Armadillo</div>
  <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
    in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
  <p class="finalsib">Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
  <div class="h3">Axelotl</div>
  <p class="finalsib">Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
    in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
  <div class="flexfooter">
    <div class="copyright">
      <p>Copyright (c) 2018 Aardvark Associates</p>
      <p>Don't copy without permission.</p>
    </div>
  </div>
</div>

CSS

body {
  font-family: "Arial", sans-serif;
  font-size: small;
  color: Black;
  line-height: 1.3;
}

body,
html {
  width: 100%;
  height: 100%;
  padding: 0;
  margin-left: 1em;
}

div.flexbody {
  display: flex;
  flex-direction: column;
  height: 100vh;
  min-height: 100%;
}

div.flexfooter {
  margin: auto 0 0 0;
}

p,
div {
  margin-top: 1em;
  margin-bottom: 1em;
}

p:first-child,
div:first-child {
  margin-top: 0;
}

p.finalsib {
  margin-bottom: 0;
}

.h1,
.h2,
.h3 {
  color: Black;
  background: none;
  font-weight: bold;
  padding-top: 1em;
  padding-bottom: 0.17em;
  margin: 1em 0 1em 0;
}

.h1,
.h2 {
  border-bottom: 1px solid #aaaaaa;
}

.h1 {
  font-size: 240%;
}

.h2 {
  font-size: 168%;
}

.h3 {
  font-size: 133%;
}

div.copyright {
  border-top: 1px solid #aaaaaa;
  padding-top: 1em;
  margin-top: 1.5em;
  font-size: 84%;
}