Ruby On Rails Junior+/Middle Developer

Itransition; Santa Cruz de Tenerife; Remote; EUR 86,000 - 110,000; Part time

Job summary

Mercor is seeking a Web Development Expert for a fully remote role. You will evaluate and replicate complex UI layouts, focusing on semantic HTML/CSS, responsive design, and accurate typography.

The role requires strong JS awareness and precise HTML/CSS craftsmanship to produce pixel-perfect results across viewports. Responsibilities include analyzing source code, comparing implementations, and justifying decisions with concrete, evidence-based notes.

Qualifications

• 3–8 years of professional web development experience in frontend or full-stack work.
• Fluency across web eras, including legacy layouts for layout.
• Command of hand-written HTML and CSS: semantic markup, flexbox, grid, media queries, and legacy float- and table-based layouts.
• Browser DevTools as muscle memory.
• Command-line comfort: unzipping archives, starting a static server, and untangling broken image references.
• Enough JavaScript to read scripts and understand their DOM impact.
• Professional written English for task justification.

Responsibilities

• Render a reference page and two candidate replications at 1920×1080; judge closeness to the original.
• Diff visual fidelity in detail: box model, typography, color, borders, image handling, z-order, and overflow.
• Read source of both attempts and grade construction quality; identify truly correct replication vs. superficially correct.
• Test responsiveness; identify defects like nav collapse at smaller viewports.
• Provide evidence-based justifications for all preferences with specific examples.
• Use the escape hatch to distinguish truly unfinishable tasks from hard ones.

Skills

HTML

CSS

Flexbox

Grid

Media queries

DevTools

JavaScript

English writing

Tools

DevTools

Job description

Web Development Expert - Fully Remote | Upto $90/hr

Mercor connects elite creative and technical talent with leading AI research labs. Headquartered in San Francisco, our investors include Benchmark, General Catalyst, Peter Thiel, Adam D'Angelo, Larry Summers, and Jack Dorsey.

Position: Frontend Engineer
Type: Contract
Compensation: $90/hour
Location: Remote

Role Responsibilities

• Render a reference page and two candidate replications at 1920×1080. Judge which is the closer reproduction, state by state.
• Diff visual fidelity in detail: box model and spacing, typography (family, size, weight, line-height, letter-spacing), color and border treatment, image and asset handling, z-order, and overflow.
• Read the source of both attempts and grade construction quality. Distinguish a replication that is genuinely correct from one that merely looks correct at one viewport.
• Test responsiveness. Identify defects such as a nav bar that looks right at 1920px but collapses at 1400px.
• Write specific, evidence-cited justifications for every preference. Provide detailed explanations like "B nests the article body in a single absolutely-positioned div, so the text overlaps the footer below 1600px, while A uses normal document flow."
• Use the "this task is broken" escape hatch with judgment. Distinguish a task that genuinely cannot be completed from one that is merely hard.

Qualifications

Must-Have

• 3–8 years of professional web development experience in frontend or full-stack work.
• Fluency across web eras, including legacy layouts like used for layout.
• Command of hand-written HTML and CSS: semantic markup, flexbox, grid, media queries, and legacy float- and table-based layouts.
• Browser DevTools as muscle memory.
• Command-line comfort: unzipping an archive, standing up a static local server, and untangling a broken image reference.
• Enough JavaScript to read a page's scripts and understand their DOM impact.
• Professional written English for task justification.

Preferred

• Prior RLHF, preference-labeling, model-evaluation, or structured code-review work.
• Pixel-perfect design-to-code experience.
• Accessibility expertise (ARIA, semantic landmarks, heading hierarchy).
• Familiarity with how LLMs fail at code generation.
• Web scraping, archiving, or DOM-parsing background.
• More than one completed Mercor project and availability in contiguous multi-hour blocks.