Generate a single, self-contained HTML file named index.html for a modern, professional, mobile-first website called "ProFishion". The file must include all CSS and JavaScript inline (no external files except for one Google Font link), use semantic HTML5 tags, and follow a sleek, minimalist, mobile-first responsive design. The layout should include: a fixed header with a glass/blur effect, logo placeholder, 5 navigation links (Features, Pricing, About, Blog, Contact), and a primary "Get Started" button, with a mobile hamburger menu that toggles open/close accessibly. The hero section should be full-width with a bold headline (<h1>), subheadline, primary CTA ("Start Free"), secondary CTA ("Learn More"), and a subtle background gradient or abstract inline SVG pattern, with optional animated decorative shapes using CSS keyframes. A features section should include a responsive 3-column grid (1 col mobile, 2 cols tablet, 3 cols desktop) with cards containing an inline SVG icon, title, and short description, with hover shadow lift effects. An about/testimonial section should feature a split layout with an illustration or image placeholder and text, plus a testimonial carousel placeholder with quotes, author, and accessible navigation buttons. A pricing section must contain 3 pricing cards (Basic, Pro, Enterprise), each showing plan name, price, feature list, and CTA button, with a "most popular" badge on one plan. Include a toggle to switch between monthly/yearly pricing using small inline JS, with accessible aria updates, and an optional settings mini-panel for billing frequency or currency. A full-width call-to-action banner must appear with strong contrast, text, and a CTA button. The footer should use a 4-column layout containing logo/tagline, product links, company/contact info, and social icon placeholders (inline SVGs), plus copyright and a subtle top border. Use CSS custom properties to mimic Sass variables for colors, typography, spacing, and shadows, and apply BEM naming convention for class names (e.g., .hero__title, .feature__card). Ensure smooth hover animations, focus-visible styles, subtle fade-in/slide-up animations with reduced-motion support, accessible contrast, and consistent button styles (primary, secondary, disabled). Add a dark mode toggle that updates a data-theme attribute and persists the choice via localStorage. Include minimal inline vanilla JS for the mobile nav toggle, dark mode toggle, pricing toggle, and optional testimonial carousel controls. Use inline SVGs for icons and at least one decorative SVG pattern. The output must be semantic, accessible (with proper aria-labels, alt texts, and logical heading order), performant, and ready to save as index.html and run locally. Return only the complete HTML file content and nothing else.