Every course/lesson/social image sits on --color-brand-900 (#001a3e) — never a photo background, never a gradient. This is the single strongest brand cue across the platform.

Pick one of the 9 background patterns (grid, dots, diagonal…) from Brand → 9 Background Patterns at 6–10% white opacity, masked to fade toward the edges. Never two patterns on one image.

A // LABEL style eyebrow in Roboto Mono, uppercase, brand-300, top-left corner. Course thumbnail: category. Lesson thumbnail: parent course name.

A 3–4px solid brand-500 bar along the top edge only — the single saturated color permitted per Principle 3 (One Signal Color). Never a border on other edges.

36–56px depending on canvas, tight leading, max 2 lines. Never centered, never a script/serif font.

A lesson thumbnail reuses its course's exact frame (same pattern, same kicker) plus a large mono index number badge (01, 02…) bottom-right — so a whole course's lessons visually belong together at a glance.

Duration / level / lesson count sits bottom-left in mono 11–12px, separated from title by a hairline, never icons-only.

0–4px radius max on the canvas itself; per Principle 4 (Sharp Geometry, Rounded Rest) these are structural surfaces, not soft cards.

Same layout, same copy — light swaps navy for white and inverts pattern/text opacity. Never mix themes within one asset.

Each thumbnail type gets a different one of the 9 background patterns (grid, dots, diagonal, concentric, blueprint, chevron-grid…) so a feed of thumbnails reads as a family, not identical clones.

Use the ph ph-* glyphs already shipped in this system (play, clock, books, shield-check, code, lightning…) inline with mono text in kickers, meta rows, and CTAs. No emoji, no hand-drawn icons, ever.