merge head/nav templates into unified head.php + header.php; semantic CSS for nav

public/assets/css/common.css

@@ -49,9 +49,13 @@ a:hover {
 }
 
 /* ============================================================
-   NAV BAR (shared across all public pages)
+   HEADER / NAV BAR (public pages)
    ============================================================ */
-.site-nav {
+header {
+  flex-shrink: 0;
+}
+
+header nav {
   background: linear-gradient(
     to bottom,
     var(--purple) 0%,
@@ -61,11 +65,9 @@ a:hover {
   display: flex;
   align-items: center;
   justify-content: space-between;
-  flex-shrink: 0;
-  /* height: 3ch; */
 }
 
-.site-nav__logo {
+header nav > a {
   font-family: "police1", sans-serif;
   font-size: 0.95rem;
   letter-spacing: 0.12em;
@@ -75,7 +77,7 @@ a:hover {
   font-weight: 400;
 }
 
-.site-nav ul {
+header nav ul {
   display: flex;
   gap: 3rem;
   align-items: center;
@@ -84,7 +86,7 @@ a:hover {
   padding: 0;
 }
 
-.site-nav ul a {
+header nav ul a {
   font-size: 0.85rem;
   letter-spacing: 0.12em;
   text-transform: uppercase;
@@ -94,11 +96,11 @@ a:hover {
   transition: opacity 0.15s;
 }
 
-.site-nav ul a:hover {
+header nav ul a:hover {
   opacity: 1;
 }
 
-.site-nav ul a[aria-current="page"] {
+header nav ul a[aria-current="page"] {
   opacity: 1;
   border-bottom: 1px solid rgba(255, 255, 255, 0.6);
   padding-bottom: 1px;