font-kerning「字間スペース」

<style type="text/css">
.common div{
  font-family   : "メイリオ", sans-serif;
  width         : 290px;
  border        : 2px solid #6495ed;
  background    : #e7e7ff;
  padding       : 10px;
}
div.cssTitle {
  margin-top    : 10px;
  background    : #6495ed;
  color         : #fff;
  font-weight   : bold;
}
.css-auto{font-kerning : auto;}
.css-none{font-kerning : none;}
.css-normal{font-kerning : normal;}
.css-font-family{font-family : 'Arial';}

<!-- html -->
<div class="common">
  <div class="cssTitle">font-kerning 表示例<br><br>
  上段：auto 中断：normal 下段：none</div>
  <div>
  <span class="css-auto css-font-family">
  To Tr Ta Tu Te Ty Wa WA We Wo Ya Yo</span><br>
  <span class="css-normal css-font-family">
  To Tr Ta Tu Te Ty Wa WA We Wo Ya Yo</span><br>
  <span class="css-none css-font-family">
  To Tr Ta Tu Te Ty Wa WA We Wo Ya Yo</span><br>
  </div>
</div>