css3 clever use of structural pseudo-class selectors

I recently saw a usage of structural pseudo-class selector on a foreign website. I thought it was very practical, so I tried it myself and recorded it:

This is the most basic style:

<span style="color: #008080;"> 1</span> <span style="color: #800000;"><style type="text/css">
</span><span style="color: #008080;"> 2</span> <span style="color: #800000;">    li</span>{
<span style="color: #008080;"> 3</span> <span style="color: #ff0000;">        list-style-type</span>:<span style="color: #0000ff;"> none</span>;
<span style="color: #008080;"> 4</span> <span style="color: #ff0000;">        float</span>:<span style="color: #0000ff;"> left</span>;
<span style="color: #008080;"> 5</span> <span style="color: #ff0000;">        width</span>:<span style="color: #0000ff;"> 60px</span>;
<span style="color: #008080;"> 6</span> <span style="color: #ff0000;">        height</span>:<span style="color: #0000ff;"> 60px</span>;
<span style="color: #008080;"> 7</span> <span style="color: #ff0000;">        background-color</span>:<span style="color: #0000ff;"> #979698</span>;
<span style="color: #008080;"> 8</span> <span style="color: #ff0000;">        margin-left</span>:<span style="color: #0000ff;"> 10px</span>;
<span style="color: #008080;"> 9</span> <span style="color: #ff0000;">        text-align</span>:<span style="color: #0000ff;"> center</span>;
<span style="color: #008080;">10</span> <span style="color: #ff0000;">        line-height</span>:<span style="color: #0000ff;"> 60px</span>;
<span style="color: #008080;">11</span> <span style="color: #ff0000;">        border-radius</span>:<span style="color: #0000ff;"> 50%</span>;
<span style="color: #008080;">13</span>     }
<span style="color: #008080;">14</span> <span style="color: #800000;"></style></span>

Contents in body:

<span style="color: #008080;"> 1</span> <span style="color: #0000ff;"><</span><span style="color: #800000;">body</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 2</span>  <span style="color: #0000ff;"><</span><span style="color: #800000;">ul</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 3</span>      <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第01个<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 4</span>      <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第02个<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 5</span>      <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第03个<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 6</span>      <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第04个<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 7</span>      <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第05个<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 8</span>      <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第06个<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;"> 9</span>      <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第07个<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">10</span>      <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第08个<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">11</span>      <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第09个<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">12</span>      <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第10个<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">13</span>      <span style="color: #0000ff;"><</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>第11个<span style="color: #0000ff;"></</span><span style="color: #800000;">li</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">14</span>  <span style="color: #0000ff;"></</span><span style="color: #800000;">ul</span><span style="color: #0000ff;">></span>
<span style="color: #008080;">15</span> <span style="color: #0000ff;"></</span><span style="color: #800000;">body</span><span style="color: #0000ff;">></span>

First is the usage of the most basic structural pseudo-class selector:

<span style="color: #008080;">1</span> <span style="color: #800000;">    li:nth-child(8)</span>{
<span style="color: #008080;">2</span> <span style="color: #ff0000;">        background-color</span>:<span style="color: #0000ff;"> #298EB2</span>;
<span style="color: #008080;">4</span>     }

The results are displayed as:

Use:nth-child(n+6) which is equivalent to:nth-child(6) and above li tag elements:

<span style="color: #008080;">1</span> <span style="color: #800000;">    li:nth-child(n+6)</span>{
<span style="color: #008080;">2</span> <span style="color: #ff0000;">        background-color</span>:<span style="color: #0000ff;"> #298EB2</span>;
<span style="color: #008080;">4</span>     }

The results are displayed as:

Similarly, use:nth-child(-n+6) which is equivalent to:nth-child(6) and the following li tag elements:

<span style="color: #008080;">1</span> <span style="color: #800000;">    li:nth-child(-n+6)</span>{
<span style="color: #008080;">2</span> <span style="color: #ff0000;">        background-color</span>:<span style="color: #0000ff;"> #298EB2</span>;
<span style="color: #008080;">4</span>     }

The results are displayed as:

Based on the above principles we can come up with some advanced ones:

For example, you can use nth-child(n+4):nth-child(-n+8) to obtain the li tag elements of :nth-child(4) and above and :nth-child(8) and below:

<span style="color: #008080;">1</span> <span style="color: #800000;">    li:nth-child(n+4):nth-child(-n+8)</span>{
<span style="color: #008080;">2</span> <span style="color: #ff0000;">        background-color</span>:<span style="color: #0000ff;"> #298EB2</span>;
<span style="color: #008080;">3</span>     }

The results are displayed as:

You can also use:nth-child(n+2):nth-child(odd):nth-child(-n+8) to get:nth-child(n+2) to:nth-child(-n+8 ) between singular li tag elements:

<span style="color: #008080;">1</span> <span style="color: #800000;">    li:nth-child(n+2):nth-child(odd):nth-child(-n+8)</span>{
<span style="color: #008080;">2</span> <span style="color: #ff0000;">        background-color</span>:<span style="color: #0000ff;"> #298EB2</span>;
<span style="color: #008080;">3</span>     }

The results are displayed as:

Finally, we can also use:nth-child(3n+1) to get even li tag elements with numbers 1, 4, 7, and 10:

<span style="color: #008080;">1</span> <span style="color: #800000;">    li:nth-child(3n+1):nth-child(even)</span>{
<span style="color: #008080;">2</span> <span style="color: #ff0000;">        background-color</span>:<span style="color: #0000ff;"> #298EB2</span>;
<span style="color: #008080;">3</span>     }

The results are displayed as: