Polish the site header based on user feedback

- Kill double underlines on nav items and brand: scope '.site-header a
  { text-decoration: none }' more specifically so the page-level 'a'
  rule in main.css can't bleed through
- Add an inline SVG logo mark next to the 'Impeccable' wordmark (reuses
  the favicon.svg glyph, inlined so Bun's HTML loader doesn't try to
  bundle '/favicon.svg' from a non-relative path)
- Add a subtle GitHub star pill (icon + 17k + small star) at the far
  right of the header; replaces the bare 'GitHub' nav text link
- Remove the duplicate .github-link floater from the hero on the landing
  page; the header pill is the single place for the stars signal now
- Mobile: stop nav items from wrapping mid-word; lower the breakpoint
  to 820px; enable horizontal scroll with a mask fade on the right;
  hide the 'Home' link on mobile (the brand is already the home link);
  hide the brand wordmark below 480px (logo glyph alone); hide the 17k
  label inside the github pill on mobile (keep the icon + star)

public/css/sub-pages.css

@@ -42,20 +42,27 @@ a {
   display: flex;
   align-items: center;
   justify-content: space-between;
-  gap: var(--spacing-lg);
-  padding: 18px clamp(var(--spacing-md), 4vw, var(--spacing-2xl));
+  gap: var(--spacing-md);
+  padding: 14px clamp(var(--spacing-md), 4vw, var(--spacing-2xl));
   background: color-mix(in oklch, var(--color-paper) 94%, transparent);
   -webkit-backdrop-filter: saturate(1.4) blur(16px);
   backdrop-filter: saturate(1.4) blur(16px);
   border-bottom: 1px solid var(--color-mist);
 }
 
+/* Kill any inherited text-decoration from page-level `a` rules. */
+.site-header a,
+.site-header a:hover {
+  text-decoration: none;
+  text-decoration-thickness: 0;
+}
+
 .site-header-brand {
   display: inline-flex;
   align-items: center;
   gap: 10px;
   font-family: var(--font-display);
-  font-size: 1.375rem;
+  font-size: 1.25rem;
   font-weight: 600;
   letter-spacing: -0.01em;
   color: var(--color-ink);
@@ -67,21 +74,38 @@ a {
   color: var(--color-accent);
 }
 
+.site-header-brand-logo {
+  width: 26px;
+  height: 26px;
+  border-radius: 6px;
+  flex-shrink: 0;
+}
+
 .site-header-brand-name {
   display: inline-block;
 }
 
+.site-header-right {
+  display: flex;
+  align-items: center;
+  gap: clamp(var(--spacing-sm), 2vw, var(--spacing-md));
+  min-width: 0;
+}
+
 .site-header-nav {
   display: flex;
   align-items: center;
-  gap: clamp(var(--spacing-sm), 2vw, var(--spacing-lg));
+  gap: clamp(var(--spacing-sm), 2vw, var(--spacing-md));
   font-family: var(--font-body);
   font-size: 0.9375rem;
   font-weight: 500;
+  min-width: 0;
 }
 
 .site-header-nav a {
   position: relative;
+  display: inline-block;
+  white-space: nowrap;
   color: var(--color-charcoal);
   padding: 4px 0;
   transition: color var(--duration-fast) var(--ease-out);
@@ -101,20 +125,68 @@ a {
   position: absolute;
   left: 0;
   right: 0;
-  bottom: -6px;
+  bottom: -4px;
   height: 2px;
   background: var(--color-accent);
   border-radius: 2px;
 }
 
-@media (max-width: 720px) {
+/* GitHub star pill — subtle, inviting nudge without shouting */
+.site-header-github {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  padding: 4px 10px 4px 8px;
+  border-radius: 99px;
+  background: var(--color-cream);
+  border: 1px solid var(--color-mist);
+  font-family: var(--font-mono);
+  font-size: 0.8125rem;
+  font-weight: 500;
+  color: var(--color-charcoal);
+  flex-shrink: 0;
+  transition:
+    background var(--duration-fast) var(--ease-out),
+    border-color var(--duration-fast) var(--ease-out),
+    color var(--duration-fast) var(--ease-out);
+}
+
+.site-header-github svg {
+  width: 14px;
+  height: 14px;
+  flex-shrink: 0;
+}
+
+.site-header-github:hover {
+  background: var(--color-paper);
+  border-color: var(--color-ink);
+  color: var(--color-ink);
+}
+
+.site-header-github-star {
+  color: #f59e0b;
+  width: 12px;
+  height: 12px;
+  flex-shrink: 0;
+}
+
+@media (max-width: 820px) {
   .site-header {
-    padding: 14px var(--spacing-md);
+    padding: 12px var(--spacing-md);
     gap: var(--spacing-sm);
   }
 
   .site-header-brand {
-    font-size: 1.125rem;
+    font-size: 1.0625rem;
+  }
+
+  .site-header-brand-logo {
+    width: 22px;
+    height: 22px;
+  }
+
+  .site-header-right {
+    gap: var(--spacing-sm);
   }
 
   .site-header-nav {
@@ -122,13 +194,33 @@ a {
     gap: var(--spacing-sm);
     overflow-x: auto;
     scrollbar-width: none;
+    -webkit-overflow-scrolling: touch;
+    /* fade the right edge so users see there's more to scroll */
+    mask-image: linear-gradient(to right, black 0%, black calc(100% - 24px), transparent 100%);
+    -webkit-mask-image: linear-gradient(to right, black 0%, black calc(100% - 24px), transparent 100%);
   }
 
   .site-header-nav::-webkit-scrollbar {
     display: none;
   }
 
-  .site-header-nav a[data-nav="github"] {
+  .site-header-nav a[data-nav="home"] {
+    /* Brand already acts as home link on mobile */
+    display: none;
+  }
+
+  .site-header-github {
+    padding: 4px 8px;
+  }
+
+  .site-header-github-label {
+    display: none;
+  }
+}
+
+@media (max-width: 480px) {
+  .site-header-brand-name {
+    /* Logo alone on narrow screens */
     display: none;
   }
 }