shape-outside: circle(50%);

shape-outside: ellipse(130px 140px at 20% 20%);

shape-outside: url("/shared-assets/images/examples/round-balloon.png");

shape-outside: polygon(50% 0, 100% 50%, 50% 100%, 0 50%);

<section class="default-example" id="default-example">
  <div class="example-container">
    <img
      class="transition-all"
      id="example-element"
      src="/shared-assets/images/examples/round-balloon.png"
      width="150" />
    We had agreed, my companion and I, that I should call for him at his house,
    after dinner, not later than eleven o'clock. This athletic young Frenchman
    belongs to a small set of Parisian sportsmen, who have taken up "ballooning"
    as a pastime. After having exhausted all the sensations that are to be found
    in ordinary sports, even those of "automobiling" at a breakneck speed, the
    members of the "Aéro Club" now seek in the air, where they indulge in all
    kinds of daring feats, the nerve-racking excitement that they have ceased to
    find on earth.
  </div>
</section>

.example-container {
  text-align: left;
  padding: 20px;
}

#example-element {
  float: left;
  width: 150px;
  margin: 20px;
}

css

/* Keyword values */
shape-outside: none;
shape-outside: margin-box;
shape-outside: content-box;
shape-outside: border-box;
shape-outside: padding-box;

/* Function values */
shape-outside: circle();
shape-outside: ellipse();
shape-outside: inset(10px 10px 10px 10px);
shape-outside: polygon(10px 10px, 20px 20px, 30px 30px);

/* Shape box with basic shape */
shape-outside: circle() border-box;
shape-outside: margin-box ellipse();

/* <url> value */
shape-outside: url("image.png");

/* <gradient> value */
shape-outside: linear-gradient(45deg, white 150px, red 150px);

/* Global values */
shape-outside: inherit;
shape-outside: initial;
shape-outside: revert;
shape-outside: revert-layer;
shape-outside: unset;

The shape-outside property is specified using the values from the list below, which define the float area for float elements. The float area determines the shape around which inline content (float elements) wrap.

none

The float area is unaffected. Inline content wraps around the element's margin box, like usual.

<shape-box>

The float area is computed according to the shape of a float element's edges (as defined by the CSS box model). This can be margin-box, border-box, padding-box, or content-box. The shape includes any curvature created by the border-radius property (behavior which is similar to background-clip).

margin-box

Defines the shape enclosed by the outside margin edge. The corner radii of this shape are determined by the corresponding border-radius and margin values. If the border-radius / margin ratio is 1 or more, then the margin box corner radius is border-radius + margin. If the ratio is less than 1, then the margin box corner radius is border-radius + (margin * (1 + (ratio - 1) ^ 3)).

border-box

Defines the shape enclosed by the outside border edge. The shape follows the normal border radius shaping rules for the outside of the border.

padding-box

Defines the shape enclosed by the outside padding edge. The shape follows the normal border radius shaping rules for the inside of the border.

content-box

Defines the shape enclosed by the outside content edge. Each corner radius of this box is the larger of 0 or border-radius - border-width - padding.

<basic-shape>

The float area is computed based on the shape created by an inset(), circle(), ellipse(), or polygon() function; other <basic-shape> functions are invalid. If a <shape-box> is also supplied, it defines the reference box for the <basic-shape> function. Otherwise, the reference box defaults to margin-box.

<image>

The float area is extracted and computed based on the alpha channel of the specified <image> as defined by shape-image-threshold.

Note: If the image is invalid, the effect is as if the keyword none had been specified. Additionally, the image must be served with CORS headers allowing its use.

shape-outside = 
  none                              |
  [ <basic-shape> || <shape-box> ]  |
  <image>                           

<basic-shape> = 
  <basic-shape-rect>  |
  <circle()>          |
  <ellipse()>         |
  <polygon()>         |
  <path()>            |
  <shape()>           

<shape-box> = 
  <visual-box>     |
  margin-box       |
  half-border-box  

<image> = 
  <url>           |
  <image()>       |
  <image-set()>   |
  <cross-fade()>  |
  <element()>     |
  <gradient>      

<basic-shape-rect> = 
  <inset()>  |
  <rect()>   |
  <xywh()>   

<circle()> = 
  circle( <radial-size>? [ at <position> ]? )  

<ellipse()> = 
  ellipse( <radial-size>? [ at <position> ]? )  

<polygon()> = 
  polygon( <'fill-rule'>? [ round <length> ]? , [ <length-percentage> <length-percentage> ]# )  

<path()> = 
  path( <'fill-rule'>? , <string> )  

<shape()> = 
  shape( <'fill-rule'>? from <position> , <shape-command># )  

<visual-box> = 
  content-box  |
  padding-box  |
  border-box   

<image()> = 
  image( <image-tags>? [ <image-src>? , <color>? ]! )  

<image-set()> = 
  image-set( <image-set-option># )  

<cross-fade()> = 
  cross-fade( <cf-image># )  

<element()> = 
  element( <id-selector> )  

<inset()> = 
  inset( <length-percentage>{1,4} [ round <'border-radius'> ]? )  

<rect()> = 
  rect( <top> , <right> , <bottom> , <left> )  

<xywh()> = 
  xywh( <length-percentage>{2} <length-percentage [0,∞]>{2} [ round <'border-radius'> ]? )  

<radial-size> = 
  <radial-extent>               |
  <length [0,∞]>                |
  <length-percentage [0,∞]>{2}  

<position> = 
  <position-one>   |
  <position-two>   |
  <position-four>  

<fill-rule> = 
  nonzero  |
  evenodd  

<length-percentage> = 
  <length>      |
  <percentage>  

<shape-command> = 
  <move-command>             |
  <line-command>             |
  close                      |
  <horizontal-line-command>  |
  <vertical-line-command>    |
  <curve-command>            |
  <smooth-command>           |
  <arc-command>              

<image-tags> = 
  ltr  |
  rtl  

<image-src> = 
  <url>     |
  <string>  

<image-set-option> = 
  [ <image> | <string> ] [ <resolution> || type( <string> ) ]?  

<cf-image> = 
  [ <image> | <color> ]  &&
  <percentage [0,100]>?  

<id-selector> = 
  <hash-token>  

<border-radius> = 
  <length-percentage [0,∞]>{1,4} [ / <length-percentage [0,∞]>{1,4} ]?  

<radial-extent> = 
  closest-corner   |
  closest-side     |
  farthest-corner  |
  farthest-side    

<position-one> = 
  left                 |
  center               |
  right                |
  top                  |
  bottom               |
  x-start              |
  x-end                |
  y-start              |
  y-end                |
  block-start          |
  block-end            |
  inline-start         |
  inline-end           |
  <length-percentage>  

<position-two> = 
  [ left | center | right | x-start | x-end ] && [ top | center | bottom | y-start | y-end ]  |
  [ left | center | right | x-start | x-end | <length-percentage> ] [ top | center | bottom | y-start | y-end | <length-percentage> ]  |
  [ block-start | center | block-end ] && [ inline-start | center | inline-end ]  |
  [ start | center | end ]{2}                         

<position-four> = 
  [ [ left | right | x-start | x-end ] <length-percentage> ] && [ [ top | bottom | y-start | y-end ] <length-percentage> ]  |
  [ [ block-start | block-end ] <length-percentage> ] && [ [ inline-start | inline-end ] <length-percentage> ]  |
  [ [ start | end ] <length-percentage> ]{2}          

<move-command> = 
  move <command-end-point>  

<line-command> = 
  line <command-end-point>  

<horizontal-line-command> = 
  hline [ to [ <length-percentage> | left | center | right | x-start | x-end ] | by <length-percentage> ]  

<vertical-line-command> = 
  vline [ to [ <length-percentage> | top | center | bottom | y-start | y-end ] | by <length-percentage> ]  

<curve-command> = 
  curve [ [ to <position> with <control-point> [ / <control-point> ]? ] | [ by <coordinate-pair> with <relative-control-point> [ / <relative-control-point> ]? ] ]  

<smooth-command> = 
  smooth [ [ to <position> [ with <control-point> ]? ] | [ by <coordinate-pair> [ with <relative-control-point> ]? ] ]  

<arc-command> = 
  arc <command-end-point> [ [ of <length-percentage>{1,2} ] && <arc-sweep>? && <arc-size>? && [ rotate <angle> ]? ]  

<command-end-point> = 
  to <position>         |
  by <coordinate-pair>  

<control-point> = 
  <position>                |
  <relative-control-point>  

<coordinate-pair> = 
  <length-percentage>{2}  

<relative-control-point> = 
  <coordinate-pair> [ from [ start | end | origin ] ]?  

<arc-sweep> = 
  cw   |
  ccw  

<arc-size> = 
  large  |
  small

HTML

html

<div class="main">
  <div class="left"></div>
  <div class="right"></div>
  <p>
    Sometimes a web page's text content appears to be funneling your attention
    towards a spot on the page to drive you to follow a particular link.
    Sometimes you don't notice.
  </p>
</div>

CSS

css

.main {
  width: 530px;
}

.left,
.right {
  background-color: lightgray;
  height: 12ex;
  width: 40%;
}

.left {
  clip-path: polygon(0 0, 100% 100%, 0 100%);
  float: left;
  shape-outside: polygon(0 0, 100% 100%, 0 100%);
}

.right {
  clip-path: polygon(100% 0, 100% 100%, 0 100%);
  float: right;
  shape-outside: polygon(100% 0, 100% 100%, 0 100%);
}

p {
  text-align: center;
}

Result