transparent text with shadow in CSS [duplicate]

Question

Is there any way to make a transparent text cut out of a background effect like the one in the following image, with CSS?
It would be sad to lose all precious SEO because of images replacing text.

I first thought of shadows but I can't figure anything out...

The image is the site background, an absolute positioned <img> tag

Answer 1

Although this is possible with CSS, a better approach would be to use an inline SVG with SVG masking. This approach has some advantages over CSS :

• Much better browser support: IE10+, chrome, Firefox, safari...
• This doesn't impact SEO as spiders can crawl SVG content (google indexes SVG content since 2010)

CodePen Demo : SVG text mask

body,html{height:100%;margin:0;padding:0;}
body{
  background:url('https://farm9.staticflickr.com/8760/17195790401_94fcf60556_c.jpg');
  background-size:cover;
  background-attachment:fixed;
}
svg{width:100%;}

<svg viewbox="0 0 100 60">
  <defs>
    <mask id="mask" x="0" y="0" width="100" height="50">
      <rect x="0" y="0" width="100" height="40" fill="#fff"/>
      <text text-anchor="middle" x="50" y="18" dy="1">SVG</text>
      <text text-anchor="middle" x="50" y="30" dy="1">Text mask</text>
    </mask>
  </defs>
  <rect x="5" y="5" width="90" height="30" mask="url(#mask)" fill-opacity="0.5"/>    
</svg>

If you aim on making the text selectable and searchable, you need to include it outside the <defs> tag. The following example shows a way to do that keeping the transparent text with the <use> tag:

body,html{height:100%;margin:0;padding:0;}
body{
  background:url('https://farm9.staticflickr.com/8760/17195790401_94fcf60556_c.jpg');
  background-size:cover;
  background-attachment:fixed;
}
svg{width:100%;}

<svg viewbox="0 0 100 60">
  <defs>
    <g id="text">
      <text text-anchor="middle" x="50" y="18" dy="1">SVG</text>
      <text text-anchor="middle" x="50" y="30" dy="1">Text mask</text>
    </g>
    <mask id="mask" x="0" y="0" width="100" height="50">
      <rect x="0" y="0" width="100" height="40" fill="#fff"/>
      <use xlink:href="#text" />
    </mask>
  </defs>
  <rect x="5" y="5" width="90" height="30" mask="url(#mask)" fill-opacity="0.5"/>
  <use xlink:href="#text" mask="url(#mask)" />
</svg>