For better readability and understanding, ruleset blocks should be organized as follow:

• Variable declarations
• @extend directives
• @include directives
• Property declarations and nested selectors

Noncompliant Code Example

.mybox {
  $my-color: green;
  color: $my-color;
  @extend %module;
  @include transition(all 0.3s ease-out);
}

Compliant Solution

.mybox {
  $my-color: green;
  @extend %module;
  @include transition(all 0.3s ease-out);
  color: $my-color;
}

See

• CSS-TRICKS Sass Style Guide