feat: add mixins file

src/styles/_mixins.scss

@@ -0,0 +1,23 @@
+@mixin background-cover($position) {
+    background-position: $position;
+    background-repeat: no-repeat;
+    background-size: cover;
+}
+
+@mixin circle($size) {
+    @include square($size);
+    border-radius: 100%;
+}
+
+@mixin position($position, $top: null, $right: null, $bottom: null, $left: null) {
+    position: $position;
+    top: $top;
+    right: $right;
+    bottom: $bottom;
+    left: $left;
+}
+
+@mixin square($size) {
+    height: $size;
+    width: $size;
+}