1.CSS-1

<h2 id="css1"></h2>
<style>#css1::before{content:"1.CSS-1";}</style>

2.ATTR-1

<h2 data-title="2.ATTR-1" id="attr1"></h2>
<style>#attr1::before{content:attr(data-title);}</style>

3.IMG-1

<h2><img src="path/to/title1.png" alt=""></h2>

4.B64-1

// PHP GD ⇒ base64 image (see code sample)

5.SVGEM-1

<object data="title1.svg" type="image/svg+xml"></object>

6.CAN-1

<canvas id="can1" width="400" height="60"></canvas>
<script>
 const c=document.getElementById('can1').getContext('2d');
 c.font='32px Arial';c.fillText('6.CAN-1',10,40);
</script>

7.WEBGL-1

// WebGL canvas – omitted for brevity

8.JS-1

<h2 id="js1"></h2>
<script>document.getElementById('js1').innerText='8.JS-1';</script>

9.EVT-1

<h2 id="evt1">(click)</h2>
<script>document.getElementById('evt1').onclick=()=>{event.target.innerText='9.EVT-1'};</script>

10.COM-1

<h2><!--10.COM-1--></h2>
<script>...extract comment...</script>

11.ENC-1

// atob(<base64>) then inject

12.IFR-1

<iframe src="title1.html"></iframe>

13.PDF-1

<embed src="title1.pdf" type="application/pdf">

14.FNT-1

// custom icon font glyphs

15.FRM-1

<input value="15.FRM-1" disabled>

16.OBJ-1

<object data="title1-content.html"></object>

17.EMB-1

<embed src="title1-content.html">

18.SHD-1

<h2 is="shadow-title-1"></h2>
<script>
 class ShadowTitle1 extends HTMLHeadingElement{
   constructor(){super();const s=this.attachShadow({mode:'closed'});
   const span=document.createElement('span');span.textContent='18.SHD-1';s.appendChild(span);}
 }
 customElements.define('shadow-title-1',ShadowTitle1,{extends:'h2'});
</script>

19.B64SVG-1

// <img src="data:image/svg+xml;base64,...">

20.XHR-1

<h2 id="xhr1"></h2>
<script>fetch('title1.txt').then(r=>r.text()).then(t=>xhr1.innerText=t);</script>