Adding a 45 degree angle to a container

Question

I have a container element that I am trying to figure out if I can shape it to have two 45 degree angles. Like this:

It is simply a rectangle now:

<

Answer 1

you can also use gradients here combined with background-size and calc() :

only borders:

#home-img-text-container {
  margin:1em;
  display:inline-block;
    background:
      linear-gradient(0deg, rgba(0,0,0,0.9), rgba(0,0,0,0.9)) top left no-repeat ,
      linear-gradient(0deg, rgba(0,0,0,0.9), rgba(0,0,0,0.9)) bottom left no-repeat ,
      linear-gradient(90deg, rgba(0,0,0,0.9), rgba(0,0,0,0.9)) top left no-repeat,
      linear-gradient(0deg, rgba(0,0,0,0.9), rgba(0,0,0,0.9)) center right no-repeat,
      linear-gradient(-45deg, transparent 1.5em, rgba(0,0,0,0.8) 1.5em, rgba(0,0,0,0.9) calc(1.5em + 3px), transparent  calc(1.5em + 3px)) bottom left no-repeat,
      linear-gradient(-135deg, transparent 1.5em, rgba(0,0,0,0.8) 1.5em, rgba(0,0,0,0.9) calc(1.5em + 3px), transparent  calc(1.5em + 3px)) top left no-repeat
      ;
  background-size: 
    calc(100% - 2.25em) 3px ,
    calc(100% - 2.25em)  3px , 
    3px 100%, 
    3px calc(100% - 4.25em), 
    100% 50%, 
    100% 50%
    ;
    padding: 30px 20px;
}
#home-img-text-description {
    font-size: 2.5em;
    line-height: 1.4em;
}

html {
  min-height:100%;
  background:linear-gradient(to bottom right, tomato, gold);
  }

  

    
WRECKING
      
& DEMOLITION
      
DONE RIGHT.
  

only background: (closest to question)

#home-img-text-container {
  margin: 1em;
  display: inline-block;
  background: 
    linear-gradient(-45deg, transparent 1.5em, rgba(0, 0, 0, 0.8) 1.5em) bottom left no-repeat, 
    linear-gradient(-135deg, transparent 1.5em, rgba(0, 0, 0, 0.8) 1.5em) top left no-repeat;
  background-size: 100% 50%;
  /* rgba(0,0,0,.8);*/
  padding: 30px 20px;
}
#home-img-text-description {
  color: #FFF;
  font-size: 2.5em;
  line-height: 1.4em;
}


html {
  background:linear-gradient(to bottom right, tomato 30%, white 30%);
  }

  

    
WRECKING
      
& DEMOLITION
      
DONE RIGHT.
  

border and background :

#home-img-text-container {
  margin:1em;
  display:inline-block;
    background:
      linear-gradient(0deg, rgba(0,0,0,0.9), rgba(0,0,0,0.9)) top left no-repeat ,
      linear-gradient(0deg, rgba(0,0,0,0.9), rgba(0,0,0,0.9)) bottom left no-repeat ,
      linear-gradient(90deg, rgba(0,0,0,0.9), rgba(0,0,0,0.9)) top left no-repeat,
      linear-gradient(0deg, rgba(0,0,0,0.9), rgba(0,0,0,0.9)) center right no-repeat,
      linear-gradient(-45deg, transparent 1.5em, rgba(0,0,0,0.8) 1.5em, rgba(0,0,0,0.9) calc(1.5em + 3px), transparent  calc(1.5em + 3px)) bottom left no-repeat,
      linear-gradient(-135deg, transparent 1.5em, rgba(0,0,0,0.8) 1.5em, rgba(0,0,0,0.9) calc(1.5em + 3px), transparent  calc(1.5em + 3px)) top left no-repeat,
      linear-gradient(-45deg, transparent 1.5em, rgba(0,0,0,0.8) 1.5em) bottom left no-repeat,
      linear-gradient(-135deg, transparent 1.5em, rgba(0,0,0,0.8) 1.5em) top left no-repeat;
  
  background-size: 
    calc(100% - 2.25em) 3px ,
    calc(100% - 2.25em)  3px , 
    3px 100%, 
    3px calc(100% - 4.25em), 
    100% 50%, 100% 50%, 
    100% 50%, 100% 50%
    ;
      /* rgba(0,0,0,.8);*/
    padding: 30px 20px;
}
#home-img-text-description {
    color: #FFF;
    font-size: 2.5em;
    line-height: 1.4em;
}


html {
  background:linear-gradient(to bottom right, tomato 25%, gold 25%);
  }

  

    
WRECKING
      
& DEMOLITION
      
DONE RIGHT.
  

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demo & codepen to play with