feat(plot): high-contrast orange elevation line on the gradient profile

[mousebrains]

The gradient/elevation plot on description.php drew its elevation line in a blue (--c-elev) that was a near-twin of the gradient bars' blue (--c-link), so the line blended into the bars — worst over the tall full-opacity "significant" bars. This recolors the line to a warm orange that contrasts with the blue bars in both light and dark themes.

Change (CSS-only, src/kayak/web/static/style.css)

	light	dark	.gp-elev width
before	--c-elev: #1565c0	--c-elev: #a9d0f5	1.6
after	--c-elev: #e65100	--c-elev: #ffa726	2

No PHP/SVG change — the <polyline class="gp-elev"> already carries no inline color (it's themed via the CSS variable), and the right-axis elevation tick labels also key off --c-elev, so they recolor to match for free.

Verification

• Rendered before/after in both themes through the real generate_gradient_profile_svg() + the actual CSS (reach: NF Payette, 16 mi); comparison images shared with the maintainer.
• biome check clean. No test pins the elevation color, and there are no visual-snapshot baselines, so nothing else is affected.

🤖 Generated with Claude Code

[mousebrains]

Code Review — #95 feat(plot): high-contrast orange elevation line on the gradient profile

Verdict: ✅ Approve. Clean, correctly scoped, and the right fix for a real legibility problem. CSS-only, one variable, zero functional surface.

Verified

• The blend is real, in both themes. Bars fill with --c-link and the "significant" bars are full-opacity (.gp-bars-sig rect { fill: var(--c-link); fill-opacity: 1 }). The old elevation colors were near-twins of those bars in both themes — light #1565c0 vs --c-link #1b5591, and dark #a9d0f5 vs --c-link #6ab0f3 — so the line genuinely disappeared over the bars in each. The recolor addresses both, not just light mode. 👍
• --c-elev is fully scoped. Grepped the repo: its only consumers are .gp-elev (line stroke) and .gp-elev-axis (right-axis label fill). No other rule, PHP, or JS reads it, so the recolor can't leak anywhere unexpected.
• No inline color to fight the variable. Confirmed in php/includes/svg_plot.php: the polyline (:564) and the axis <text> (:570) are emitted with class= only — no inline stroke/fill/style. So the PR's "tick labels recolor for free" is accurate, and the variable is the single source of truth.

Worth noting (positive)

Blue ↔ orange is also one of the better colorblind-safe pairings (deuteranopia/protanopia separate it cleanly, unlike a red/green choice), so this improves accessibility, not just aesthetics. #e65100 on the white surface clears WCAG 1.4.11 non-text contrast (~3.7:1 ≥ 3:1).

Notes

• Verification approach fits a pure color tweak: rendered before/after through the real generator + CSS in both themes, biome clean, and nothing pins the color in tests or snapshot baselines. Nothing more to unit-test here.
• Trivial nit (ignore at will): this reads more like a fix/style (restoring legibility) than a feat, but that's purely a conventional-commit label preference.

🤖 Reviewed with Claude Code