//*********************************4*****************************
@mixin img-responsive($display: block) {
    display: $display;
    max-width: 100%;  // Part1: Set a maximum relative to the parent
    height: auto; // Part2: Scale the height accorging to the width, otherwise you get stretching
}
// Sizing shortcuts

@mixin size($width, $height) {
  width: $width;
  height: $height;
}

@mixin square($size) {
  @include size($size, $size);
}
