Kaisei Yasuzaki

HTML( Core )

Semantic markup that reads correctly for search engines and assistive technology. Hands-on experience coding HTML emails within email-client constraints.

e.g. Structure design for LPs and corporate sites ／ HTML email coding ／ OGP and structured data

CSS( Core )

Responsive layouts and faithful design reproduction. Comfortable with both Sass and Tailwind CSS; animations from lightweight CSS-only to GSAP.

e.g. Pixel-faithful reproduction of design comps ／ Scroll-triggered fade / slide effects ／ Complex Grid / Flex layouts ／ Sass architecture, Tailwind workflows

JavaScript( Core )

All the moving parts of a UI — lightweight hand-rolled implementations or libraries like Swiper, chosen per project.

e.g. Sliders, modals, accordions ／ Form validation and submission ／ Scroll effects with IntersectionObserver ／ API integration with fetch

React.js( Practical )

Component decomposition and organized state management, separating loading / error / result states by design.

e.g. State design for chat-style UIs ／ Dynamic UI such as tabs and filters ／ Extracting shared logic into custom hooks

Next.js( Core )

App Router-first: static generation, SSR and API implementation via Route Handlers. This portfolio itself is built with Next.js.

e.g. App Router site architecture ／ APIs with Route Handlers ／ Metadata / OGP / SEO setup ／ Deployment on Vercel

TypeScript( Core )

Type-safe frontend work, from typing API responses to designing component props.

e.g. Typed React / Next.js components ／ API response and JSON schema typing ／ Migrating JavaScript codebases to TypeScript

PHP( Supported )

Mainly WordPress-related logic: theme customization, contact form handling and the practical scope of web production work.

e.g. PHP adjustments inside WordPress themes ／ Mail form submission and validation ／ Light modification of existing code

WordPress( Practical )

From HTML-to-theme conversion to original themes, built so clients can update content themselves from the admin panel.

e.g. Converting static sites into WordPress themes ／ Custom post types and taxonomies ／ Plugin setup such as Contact Form 7 ／ Maintenance of existing sites

Python( Practical )

API development with FastAPI and business automation including Excel / Word processing. The backend of katadoc is built in Python.

e.g. REST APIs with FastAPI ／ Automated Excel documents with openpyxl ／ Document processing with the OpenAI API ／ Automation scripts for routine work

Git( Practical )

History management with rollback in mind: branch-based feature work and delivery via GitHub.

e.g. Branch-based feature development ／ Delivery and update management on GitHub ／ Conflict resolution and history cleanup