HTML/CSS AI Training Developer (Remote Contract)

About OpenTrain

OpenTrain is the #1 platform for building careers in AI training and data labeling. We help people start and grow durable freelance careers teaching AI — find projects, build a unified training portfolio, and apply in minutes. Creating an OpenTrain account is free.

OpenTrain AI is the hiring organization for this role. We run remote, contract projects that let contributors shape how state-of-the-art models behave while working flexibly from anywhere.

About AI training work

AI training (data labeling / annotation) is the human side of building intelligent systems — people provide examples, corrections, and reasoning that models learn from. Work ranges from evaluating model outputs to writing reference answers and crafting prompts that guide models toward correct behavior.

This role focuses on frontend code: reviewing AI-generated HTML/CSS, writing clear, correct reference implementations and step-by-step explanations, and ranking multiple model responses by technical accuracy and explanation quality.

The role

OpenTrain AI is recruiting an HTML/CSS AI Training Developer to review AI-generated frontend code and produce high-quality reference answers and reasoning. You will evaluate correctness, accessibility, responsiveness, and maintainability, and you will craft explanations and prompts that improve model outputs.

This is a remote contractor, part-time role with hourly pay. You will work directly on examples of semantic HTML, Flexbox and Grid layouts, responsive patterns, accessibility, cross-browser behavior, CSS architecture, and performance considerations.

What you'll do

Day-to-day you will evaluate model responses, write authoritative reference implementations, and produce step-by-step reasoning that teaches models to prefer best practices. Tasks will include direct code review, explanation writing, and comparative ranking of multiple outputs.

• Review AI-generated HTML/CSS for correctness, clarity, accessibility, responsiveness, and prompt adherence.
• Identify issues in semantic structure, layout behavior, CSS specificity, browser quirks, and performance.
• Write high-quality reference answers and detailed explanations demonstrating best practices.
• Compare and rank multiple model responses by technical accuracy and reasoning quality.
• Create detailed prompts and test cases across HTML and CSS topics to support training.
• Test outputs for inaccuracies and unsafe recommendations in realistic UI scenarios.

Requirements

You must be an expert in frontend development with proven, professional experience and the ability to write clear technical explanations in English. Candidates must meet every substantive requirement listed below.

• 4+ years building production UIs with semantic HTML and modern CSS.
• Expert-level layout knowledge: Flexbox, Grid, responsive patterns, component-based styling.
• Strong accessibility knowledge: semantic structure, ARIA basics, keyboard navigation, focus management, and WCAG-aware design.
• Deep understanding of browser behavior: box model, stacking context, positioning, rendering quirks, cross-browser testing strategy.
• Experience with CSS maintainability: BEM-style naming, design tokens, variables, theming, and avoiding specificity issues.
• Minimum C1 English proficiency for clear technical explanations and following detailed guidelines.
• Bachelor’s degree in Computer Science, Design, HCI, or related field — or equivalent practical experience.
• Prior experience with AI data training, annotation, or evaluating AI-generated technical content is a strong plus.

Work details & compensation

This is a remote, contractor position. Work is part-time with a minimum expected time commitment and hourly compensation as listed below. OpenTrain hires contributors across many countries; contractors are engaged as independent workers.

You will perform both evaluation (rating) tasks and text-generation tasks (writing reference solutions and explanations) as part of the project workflow.

• Time requirement: 20+ hours/week.
• Pay: USD 70.00 per hour (hourly rate fixed at $70/hr).
• Employment types: Contractor, Part-time.
• Languages: English (C1 or higher).
• Hiring countries (examples): Vietnam, Timor-Leste, Thailand, Singapore, Pakistan, Philippines, Nepal, Malaysia, Sri Lanka, Cambodia, Indonesia, Bhutan, Bangladesh, India, Brazil, Germany, United States.

How to apply

To apply, create or sign in to your OpenTrain account and submit an application for this project. OpenTrain will review applications and may request samples or short technical assessments to verify CSS and accessibility expertise.

When preparing your application, include a concise summary of relevant experience, links or code samples demonstrating semantic HTML and modern CSS work, and any prior AI training or annotation experience.