Senior HTML/CSS Developer for AI Training (Liverpool)

About the role

Prolific is seeking senior HTML/CSS developers to join its Expert Network and help train cutting‑edge AI models. You will evaluate AI‑generated frontend code, provide feedback, and ensure high‑quality, accessible markup.

Key responsibilities

• Review AI‑generated HTML/CSS for functional correctness, semantic structure and best‑practice compliance.
• Validate AI explanations of layout and styling decisions.
• Render and test markup across browsers to verify visual output and accessibility.
• Annotate model performance, highlighting issues such as inefficient selectors or hallucinated properties.
• Provide structured feedback to improve the model’s reasoning on responsive design and component architecture.

Required profile

• BSc or higher in Computer Science, Software Engineering, Web Development or related field.
• Proven senior‑level experience as a Frontend Developer or UI Engineer specializing in HTML/CSS.
• Deep knowledge of CSS cascade, specificity, box model, Flexbox, CSS Grid, WCAG accessibility standards and cross‑browser compatibility.
• Commitment to delivering one‑hour uninterrupted paid tasks.

Required skills

• HTML5
• CSS3/4 (custom properties, animations, modern layout systems)
• Flexbox & CSS Grid
• BEM methodology, design tokens
• Tailwind CSS, SASS/SCSS, CSS Modules
• Browser DevTools, accessibility auditing tools (axe, Lighthouse)
• Cross‑browser testing platforms

What we offer

• Pay up to $40 per hour, depending on experience.
• Flexible, task‑based work that can be completed remotely.
• Opportunity to influence the development of advanced AI models.