Как создать градиентный фон на всю web страницу?

html,body{ 
  background:#222; 
  height:100%; 
} 
.body_elem{ 
  height:100%; 
  position:fixed; 
  top:0; 
  bottom:0; 
  left:0; 
  right:0; 
  background:linear-gradient(to left,#111,#221c44); 
  filter:blur(10px); 
} 
.elem1{ 
  width:50%; 
  height:50%; 
  border-radius:30em/19em; 
    background:linear-gradient(to left,#111,#221c44); 
  transform:rotate(30deg)translateY(90px); 
  filter:blur(40px); 
} 
.elem1-1{ 
  width:100px; 
  height:20px; 
  background:#fff; 
  transform:translate(205px,105px); 
  filter:blur(50px); 
} 
.elem2{ 
  width:50%; 
  height:50%; 
  border-radius:30em/19em; 
    background:linear-gradient(to left,#111,#221c44); 
  transform:rotate(-20deg)translateY(-80px); 
  filter:blur(10px); 
  float:right; 
} 
.elem2-1{ 
  width:200px; 
  height:300px; 
  background:#222; 
  transform:rotate(80deg); 
  border-radius:80em/30em; 
  filter:blur(100px 
  ); 
} 
 
.body-elem-2{ 
  position: absolute; 
  top:0; 
  left:0; right:0; 
  width:80%; 
  margin:auto; 
} 
h2{ 
  color:#fff; 
  font-family:Verdana, serif; 
  font-size:2em; 
} 
.body-elem-2 p{ 
  color:#fbfbfb; 
  font-size:1.4em; 
  font-family:"Times New Roman", sans-serif; 
} 
img{ 
  display:block; 
  margin:auto; 
}

<div class="body_elem"> 
<div class="elem1"> 
  <div class="elem1-1"></div> 
</div> 
<div class="elem2"> 
  <div class="elem2-1"></div> 
</div> 
</div> 
 
<div class="body-elem-2"> 
  <h2>New post</h2> 
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  <img src="http://via.placeholder.com/550x250" alt=""> 
  <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Molestiae, esse eveniet nam autem recusandae quas voluptates totam eligendi dolorum. Cum, dolorem rerum ullam, cumque ad fuga quas incidunt eum laboriosam blanditiis, nesciunt fugit pariatur perferendis nemo distinctio aspernatur animi ratione!</p> 
</div>