Draw triangles through CSS borders

Triangles can be drawn through the CSS border. Different style combinations have different effects, and its size, color, and direction can be controlled. Look at the various graphics below. I believe there may be many more graphics that you have never seen.

Write the public style first:

<span style="color: #008080;">1</span> <span style="color: #800000;">.border </span>{
<span style="color: #008080;">2</span> <span style="color: #ff0000;">    width</span>:<span style="color: #0000ff;"> 0</span>;
<span style="color: #008080;">3</span> <span style="color: #ff0000;">    height</span>:<span style="color: #0000ff;"> 0</span>;
<span style="color: #008080;">4</span>     
<span style="color: #008080;">5</span> <span style="color: #ff0000;">    border-color</span>:<span style="color: #0000ff;"> transparent</span>;
<span style="color: #008080;">6</span> <span style="color: #ff0000;">    border-width</span>:<span style="color: #0000ff;"> 1rem</span>;
<span style="color: #008080;">7</span> <span style="color: #ff0000;">    border-style</span>:<span style="color: #0000ff;"> solid</span>;
<span style="color: #008080;">8</span> }

Based on the above css, add the following combination code to control the direction of the triangle:

<span style="color: #008080;">1</span> <span style="color: #800000;">border-left-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-right-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-top-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-bottom-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-left-color: #000;
</span><span style="color: #008080;">2</span> <span style="color: #800000;">border-bottom-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-right-color: #000;
</span><span style="color: #008080;">2</span> <span style="color: #800000;">border-bottom-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-right-color: #000;
</span><span style="color: #008080;">2</span> <span style="color: #800000;">border-top-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-left-color: #000;
</span><span style="color: #008080;">2</span> <span style="color: #800000;">border-top-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-top-color: #000;
</span><span style="color: #008080;">2</span> <span style="color: #800000;">border-bottom-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-left-color: #000;
</span><span style="color: #008080;">2</span> <span style="color: #800000;">border-right-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-top-color: #000;
</span><span style="color: #008080;">2</span> <span style="color: #800000;">border-left-color: #000;
</span><span style="color: #008080;">3</span> <span style="color: #800000;">border-bottom-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-top-color: #000;
</span><span style="color: #008080;">2</span> <span style="color: #800000;">border-left-color: #000;
</span><span style="color: #008080;">3</span> <span style="color: #800000;">border-right-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-bottom-color: #000;
</span><span style="color: #008080;">2</span> <span style="color: #800000;">border-left-color: #000;
</span><span style="color: #008080;">3</span> <span style="color: #800000;">border-right-color: #000;</span>

<span style="color: #008080;">1</span> <span style="color: #800000;">border-top-color: #000;
</span><span style="color: #008080;">2</span> <span style="color: #800000;">border-right-color: #000;
</span><span style="color: #008080;">3</span> <span style="color: #800000;">border-bottom-color: #000;</span>

Also this effect below,

<span style="color: #008080;">1</span> <span style="color: #800000;">border-left-color: #000;
</span><span style="color: #008080;">2</span> <span style="color: #800000;">border-right-color: #000;
</span><span style="color: #008080;">3</span> <span style="color: #800000;">border-left-width: 3rem;</span>

Different combinations produce different effects. You can try the effects brought by various combinations.