Added Masthead, CMDPalette and PostHeader Components

src/styles/mixins/containers.css

@@ -0,0 +1,25 @@
+@define-mixin responsive-wrapper $vspacing: 0, $hspacing: var(--spacing-cozy),
+  $fontSize: var(--typo-size-responsive) {
+  @mixin mx auto;
+
+  max-width: clamp(60ch, 90vw, 90ch);
+  padding: $vspacing $hspacing;
+  font-family: var(--font-body);
+  font-size: $fontSize;
+}
+
+@define-mixin layout-wrapper {
+  @mixin mx auto;
+  @mixin px var(--spacing-comfortable);
+  width: 100%;
+  max-width: var(--layout-max-width);
+
+  @media screen and (--max-layout) {
+    @mixin px var(--spacing-comfortable);
+  }
+}
+
+@define-mixin position $position: absolute, $inset-values {
+  position: $position;
+  inset: $inset-values;
+}