Two Divs In One Row

Can you help me to make something like that?

Solution 1:

You can use the calc() function in CSS3:

.div1 {
  width: 300px;
  border: 5px solid red;
  float: left;
}

.div2 {
  -webkit-width: calc(100% - 300px);
  -moz-width: calc(100% - 300px);
  -o-width: calc(100% - 300px);
  width: calc(100% - 300px);
  border: 5px solid green;
  float:left;
}