我怎样才能使十进制列表从1到2在下面的代码。不能弄清楚，也许我做了一些错误的标签。请检查下面的代码。结果只打印数字1

div {
  background-color: white;
  width: 300px;
  border: 2px solid red;
  padding: 20px;
  margin: 10px;
}
ul.a {list-style-type: disc;}
ol.f {list-style-type: decimal;}
ol.u {list-style-type: upper-roman;}
ol.t {list-style-type: upper-latin;}
ol.p {list-style-type: lower-latin;}
ol.q {list-style-type: lower-roman;}

<div>
<font size="6"
          face="arial"
          color="light blue">
          Aircraft Types
    </font>
<ul class="a">
  <li>General Aviation (piston-driven engines)</li>
      <ol class="f">
        <li>Single-Engine Aircraft</li>
      </ol>
      <ul>
        <ol class="u">
        <li>Tail wheel</li>
        <li>Tricycle</li>
        </ol>
      </ul>
      <ol class="f">
        <li>Dual-Engine Aircraft</li>
      </ol>
      <ul>
      <ol class="t">
        <li>Wing-mounted engines</li>
        <li>Push-pull fuselage-mounted engines</li>
      </ol>
      <ul>
      </ul>
      </ul>

</ul>
<ul class="a">
    <li>Commercial Aviation (jet engines)</li>
      <ol class="f">
        <li>Dual Engine</li>
      </ol>
      <ul>
      <ol class="p">
        <li>Wing-mounted engines</li>
        <li>Fuselage-mounted engines</li>
      </ol>
      </ul>
      <ol class="f">
        <li>Tri-Engine</li>
      </ol>
      <ul>
      <ol class="q">
        <li>Third engine in vertical stabilizer</li>
        <li>Third engine in fuselage</li>
      </ol>
      </ul>
</ul>
</div>

我试着移出标签，但我无法理解。我想让十进制数字按升序排列。我的代码只显示1