Design a high-fidelity desktop web UI mockup, 16:10, rendered as a flat screenshot -- no browser chrome, no laptop frame, no hands, no desk, no perspective.

Brand: Subnaut. A developer tool. Tone: precise, quiet, engineered. Not playful, no gradients, no glow, no 3D, no stock-photo people, no purple-blue SaaS look.

Palette, used exactly:
  background   #ffffff
  raised panel #fbfbfa
  primary text #0a0a0a
  body text    #46464a
  muted text   #8a8a90
  hairline     #e8e8e6
  accent       #12a37a  (a restrained green -- use sparingly, for one action only)

Type: a clean grotesque sans (Inter/Helvetica feel) for prose. A monospace face for labels, eyebrows, code and buttons -- uppercase, wide letter-spacing, small.

Layout: generous whitespace, a strict 12-column grid, thin 1px hairline rules as the main separator instead of borders or shadows. Left-aligned. Flat.

Mood reference: the Bittensor site, Linear's docs, Stripe's density -- engineering documentation, not a marketing splash.

Page: a searchable catalogue of about 700 items.

Left rail: filter groups with checkbox lists and small counts -- Category, Source, Author. Muted monospace group labels.

Main: a search field spanning the width with a leading magnifier icon, a row of active filter chips beneath it, then a dense responsive grid of cards, 3 across. Each card: a small category glyph, a bold name, two lines of muted description, and a row of tiny monospace tags at the bottom. Hairline borders, flat, tight but not cramped.

Above the grid, a thin stats row: three numbers with small uppercase labels (TOTAL, BUNDLED, COMMUNITY).

One card is shown in a hover state -- the hairline darkens slightly, no lift, no shadow.

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If the result is wrong, reply with one of these:
  Use the accent on exactly one element. Everything else is black, grey and white.
  Remove all gradients, shadows, rounded cards and illustrations. Flat, hairline rules only.
  Double the whitespace. Reduce to half the elements.

Dark theme: background #0a0a0a, raised #131313, primary text #f4f4f5, muted #9b9ba3, hairline #26262b, accent #4fc69a.
Mobile: render at 9:16, single column, hamburger in the top bar.
