■レイアウト：rowとcol：カラム単位での垂直方向整列
align-self-start
align-self-center
align-self-end
<div class="row">
<div class="col align-self-start">align-self-start</div><!-- 垂直上寄せ -->
<div class="col align-self-center">align-self-center</div><!-- 垂直中央寄せ -->
<div class="col align-self-end">align-self-end</div><!-- 垂直下寄せ -->
</div>