fix(styles): correct cross-root token scoping for marimo and gitea

Two related style bugs from the editorial theme port:

marimo.css — our :root token declarations never reached marimo app
descendants. Marimo declares its own tokens on .marimo (class selector,
specificity 0,1,0), which beats :root (0,0,1), so every --background,
--primary, --card, etc. inside the notebook fell back to marimo's
light-dark() defaults. Result: dark navy cell chrome, unreadable form
dropdown row, broken contrast across cells.

Fix: change every :root in marimo.css to ":root, .marimo" so our tokens
apply at the same specificity as marimo's and win by load order.

gitea home.tmpl — the .section-header div was rendering with a dark
navy background behind "Services / Infrastructure" (black text on dark
navy = invisible). Defensively force transparent bg + zero padding/border
on the section-header wrapper and its h2 so no inherited chrome leaks
through.

assets/css/marimo.css

@@ -6,7 +6,7 @@
 /* ============================================
    HTI-5 COLOR PALETTE
    ============================================ */
-:root {
+:root, .marimo {
   --background:          #F7F5F0;
   --foreground:          #1A1A18;
   --card:                #FAFAF7;
@@ -46,7 +46,7 @@
 /* ============================================
    FONT CONFIGURATION
    ============================================ */
-:root {
+:root, .marimo {
   --monospace-font: var(--font-mono);
   --text-font: var(--font-body);
   --heading-font: var(--font-display);
@@ -58,7 +58,7 @@
 /* ============================================
    MARIMO SEMANTIC VARIABLES
    ============================================ */
-:root {
+:root, .marimo {
   --popover: var(--card);
   --popover-foreground: var(--foreground);
 
@@ -94,7 +94,7 @@
    Remap neutral scales to HTI-5 warm cream palette.
    Steps 11-12 must be dark for text on light bg.
    ============================================ */
-:root {
+:root, .marimo {
   /* Gray → Warm cream/linen */
   --gray-1:  #F7F5F0;
   --gray-2:  #F0EDE6;
@@ -309,7 +309,7 @@
 /* ============================================
    TAILWIND PROSE - Markdown content
    ============================================ */
-:root {
+:root, .marimo {
   --tw-prose-body: var(--foreground);
   --tw-prose-headings: var(--foreground);
   --tw-prose-lead: var(--muted-foreground);

infra/gitea/custom/templates/home.tmpl

@@ -63,6 +63,9 @@
 /* Section header */
 .homelab-dashboard .section-header {
     margin-bottom: 1.5rem;
+    background: transparent !important;
+    padding: 0 !important;
+    border: none !important;
 }
 .homelab-dashboard .section-eyebrow {
     font-family: "JetBrains Mono", "Fira Code", monospace;
@@ -81,6 +84,10 @@
     color: var(--color-text) !important;
     line-height: 1.2 !important;
     border: none !important;
+    background: transparent !important;
+    padding: 0 !important;
+    margin: 0 !important;
+    display: block !important;
 }
 
 /* Grid */