例のアレ

index.html

<style>
  @charset 'UTF-8';
  @font-face {
    font-family: 'Noto Sans Japanese';
    font-style: normal;
    font-weight: 100;
    src: url(https://fonts.gstatic.com/ea/notosansjapanese/v6/NotoSansJP-Thin.woff2) format('woff2'), url(https://fonts.gstatic.com/ea/notosansjapanese/v6/NotoSansJP-Thin.woff) format('woff'), url(https://fonts.gstatic.com/ea/notosansjapanese/v6/NotoSansJP-Thin.otf) format('opentype');
  }
  body {
    background-color: #222426;
    font-family: 'Noto Sans Japanese';
  }
  nav {
    align-items: flex-end;
    bottom: 0;
    display: flex;
    flex-direction: row;
    justify-content: center;
    position: fixed;
    width: 100%;
  }
  nav a {
    background-color: #E2E4E6;
    border: 1px solid #828486;
    margin: 0 0.5ex;
    padding: 1ex 2em;
    transition: all 0.25s;
    transform: translateY(1ex);
  }
  nav a:hover,
  nav a:active,
  nav a:focus,
  nav a.selected {
    transform: translateY(0ex);
  }
</style>

<nav>
    <a class="selected">
        ホーム
    </a>
    <a>
        通知
    </a>
    <a>
        メッセージ
    </a>
</nav>