How to reduce the img size

Question

In my code CSS is no longer working, the CSS which I applied to the sections!

This image doesn't shrink, what am I missing out?

in website:

In HTML Code is:

<section  class="sec5 container">
   <div class="blockcontainer">
      <img src="img/campanha.jpg">
   </div>

In CSS is:

.blockcontainer{
  width: 10%;
  display: block;
  margin: 0 auto;
  box-sizing: border-box;
 }

Answer 1

You have a mistake in your CSS,

.blockcontainer{
  width: 10%;
  display: block;
  margin: 0 auto;
  box-sizing: border-box;
 }
.blockcontainer img{
  width: 100%;
}

.block_container should be changed into .blockcontainer