backdrop-filter

La propiedad CSS de backdrop-filter le permite aplicar efectos gráficos como el desenfoque o el cambio de color al área detrás de un elemento. Debido a que se aplica a todo lo que está detrás del elemento, para ver el efecto debe hacer que el elemento o su fondo sean al menos parcialmente transparentes.

/* Valor de palabra clave */
backdrop-filter: none;

/* URL al filtro SVG */
backdrop-filter: url(commonfilters.svg#filter);

/* valores <filter-function> */
backdrop-filter: blur(2px);
backdrop-filter: brightness(60%);
backdrop-filter: contrast(40%);
backdrop-filter: drop-shadow(4px 4px 10px blue);
backdrop-filter: grayscale(30%);
backdrop-filter: hue-rotate(120deg);
backdrop-filter: invert(70%);
backdrop-filter: opacity(20%);
backdrop-filter: sepia(90%);
backdrop-filter: saturate(80%);

/* Múltiples filtros */
backdrop-filter: url(filters.svg#filter) blur(4px) saturate(150%);

/* Valores globales */
backdrop-filter: inherit;
backdrop-filter: initial;
backdrop-filter: unset;

none

No se aplica filtro al fondo.

<filter-function-list>

Una lista separada por espacios de <filter-function> o un filtro SVG que se aplicará al fondo.

none | <filter-function-list>
where 
<filter-function-list> = [ <filter-function> | <url> ]+
where 
<filter-function> = <blur()> | <brightness()> | <contrast()> | <drop-shadow()> | <grayscale()> | <hue-rotate()> | <invert()> | <opacity()> | <saturate()> | <sepia()>
where 
<blur()> = blur( <length> )
<brightness()> = brightness( <number-percentage> )
<contrast()> = contrast( [ <number-percentage> ] )
<drop-shadow()> = drop-shadow( <length>{2,3} <color>? )
<grayscale()> = grayscale( <number-percentage> )
<hue-rotate()> = hue-rotate( <angle> )
<invert()> = invert( <number-percentage> )
<opacity()> = opacity( [ <number-percentage> ] )
<saturate()> = saturate( <number-percentage> )
<sepia()> = sepia( <number-percentage> )
where 
<number-percentage> = <number> | <percentage>
<color> = <rgb()> | <rgba()> | <hsl()> | <hsla()> | <hex-color> | <named-color> | currentcolor | <deprecated-system-color>
where 
<rgb()> = rgb( <percentage>{3} [ / <alpha-value> ]? ) | rgb( <number>{3} [ / <alpha-value> ]? ) | rgb( <percentage>#{3} , <alpha-value>? ) | rgb( <number>#{3} , <alpha-value>? )
<rgba()> = rgba( <percentage>{3} [ / <alpha-value> ]? ) | rgba( <number>{3} [ / <alpha-value> ]? ) | rgba( <percentage>#{3} , <alpha-value>? ) | rgba( <number>#{3} , <alpha-value>? )
<hsl()> = hsl( <hue> <percentage> <percentage> [ / <alpha-value> ]? ) | hsl( <hue>, <percentage>, <percentage>, <alpha-value>? )
<hsla()> = hsla( <hue> <percentage> <percentage> [ / <alpha-value> ]? ) | hsla( <hue>, <percentage>, <percentage>, <alpha-value>? )
where 
<alpha-value> = <number> | <percentage>
<hue> = <number> | <angle>

.box {
  background-color: rgba(255, 255, 255, 0.3);
  border-radius: 5px;
  font-family: sans-serif;
  text-align: center;
  line-height: 1;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  max-width: 50%;
  max-height: 50%;
  padding: 20px 40px;
}

html,
body {
  height: 100%;
  width: 100%;
}

body {
  background-image: url('https://interactive-examples.mdn.mozilla.net/media/examples/firefox-logo.svg');
  background-position: center center;
  background-repeat: no-repeat;
  background-size: cover;
}

.container {
  align-items: center;
  display: flex;
  justify-content: center;
  height: 100%;
  width: 100%;
}

<div class="container">
  <div class="box">
    <p>backdrop-filter: blur(10px)</p>
  </div>
</div>

• filter
• Publicación del blog de Dom Neill con ejemplos
• Creación de efectos de transparencia similares a iOS en CSS con filtro de fondo