Launchpad

You are a senior product designer and front-end engineer. Build a high-converting, dark-themed landing page for my software product as a single HTML file (HTML + CSS + vanilla JavaScript — no frameworks, no external images).

PRODUCT
- Product name: [Your product name]
- What it does (one sentence): [e.g. GST invoicing and UPI payment links for Indian freelancers and small businesses]
- Who it's for: [your audience]
- Support email: [Your email address]

DESIGN
- Dark background #07080D with surfaces #0E1018 and #141724, hairline borders rgba(255,255,255,0.08)
- Accent gradient from violet #8B5CF6 to cyan #22D3EE for highlights, the logo mark and the "Most popular" plan
- Fonts (Google Fonts): "Space Grotesk" for headings, "Inter" for body text
- A subtle grid pattern and soft radial glow behind the hero, 12–22px rounded corners, crisp and minimal

SECTIONS
1. Sticky blurred header: logo, links (Features, How it works, Pricing, FAQ), "Log in" and a white "Start free" button, plus a mobile menu
2. Centred hero: a "New" announcement pill, a 3-part headline with the middle phrase in the gradient, a 2-line subheading, two CTAs and a small note about the free plan
3. A product mockup built only with HTML/CSS: a browser window with a sidebar, 4 KPI cards (rupee amounts with Indian digit grouping, e.g. ₹4,82,300), a bar chart and a recent-invoices list with coloured status chips, plus a floating "payment received" toast
4. A strip of 6 text-only customer wordmarks
5. Features: 6 cards with inline SVG icons
6. How it works: 3 numbered steps
7. Pricing: a Monthly/Yearly toggle (yearly = 2 months free) that switches prices with JavaScript; 3 plans in ₹ (Free, ₹499/month, ₹1,499/month); the middle plan highlighted with a gradient border; a note that prices exclude 18% GST
8. One large testimonial quote
9. FAQ using <details>/<summary> with a "+" icon that rotates when open
10. A final CTA band and a 4-column footer

QUALITY BAR
- Fully responsive (the mockup stacks neatly on mobile), accessible (aria-pressed on the toggle, focus states, semantic HTML) and respects prefers-reduced-motion
- Meta title, description and Open Graph tags written for my product

OUTPUT
Return the full HTML file in one code block, then suggest 3 alternative headlines I could A/B test.