feat(docs): refine product showcase and branding

docs/app/base.css

@@ -137,107 +137,6 @@ p {
   transform: translateY(0);
 }
 
-.site-header {
-  position: fixed;
-  z-index: 100;
-  top: 16px;
-  right: 0;
-  left: 0;
-  width: min(calc(100% - 32px), 1260px);
-  margin-inline: auto;
-  border: 1px solid rgba(220, 212, 224, 0.82);
-  border-radius: 18px;
-  background: rgba(251, 250, 252, 0.82);
-  box-shadow: 0 12px 40px rgba(42, 26, 49, 0.08);
-  backdrop-filter: blur(20px) saturate(1.4);
-  -webkit-backdrop-filter: blur(20px) saturate(1.4);
-}
-
-.header-inner {
-  display: grid;
-  grid-template-columns: 1fr auto 1fr;
-  align-items: center;
-  height: 64px;
-  padding: 0 10px 0 17px;
-}
-
-.brand {
-  display: inline-flex;
-  align-items: center;
-  gap: 10px;
-  width: max-content;
-  font-family: var(--font-display);
-  font-size: 19px;
-  font-weight: 750;
-  letter-spacing: -0.04em;
-}
-
-.brand-mark-shell {
-  display: grid;
-  width: 38px;
-  height: 38px;
-  place-items: center;
-  border: 1px solid #eadcf1;
-  border-radius: 11px;
-  background: white;
-  box-shadow: 0 5px 15px rgba(105, 42, 145, 0.08);
-}
-
-.brand-mark-shell svg {
-  width: 27px;
-  height: 27px;
-}
-
-.brand-name {
-  transform: translateY(-1px);
-}
-
-.desktop-nav {
-  display: flex;
-  align-items: center;
-  gap: 3px;
-  padding: 4px;
-  border-radius: 13px;
-  background: rgba(239, 235, 241, 0.7);
-}
-
-.desktop-nav a {
-  padding: 7px 14px;
-  border-radius: 10px;
-  color: var(--ink-soft);
-  font-size: 13px;
-  font-weight: 650;
-  transition: background 160ms ease, color 160ms ease;
-}
-
-.desktop-nav a:hover {
-  background: white;
-  color: var(--ink);
-}
-
-.header-github {
-  justify-self: end;
-}
-
-.menu-button {
-  display: none;
-  width: 42px;
-  height: 42px;
-  place-items: center;
-  border: 0;
-  border-radius: 11px;
-  background: var(--surface-soft);
-  cursor: pointer;
-}
-
-.menu-button svg {
-  width: 21px;
-}
-
-.mobile-nav {
-  display: none;
-}
-
 .button {
   display: inline-flex;
   min-height: 52px;
@@ -322,4 +221,3 @@ p {
   opacity: 1;
   transform: translateY(0);
 }
-