COSESAI

Superscript & Subscript Converter Field Guide: Unicode That Survives the Copy-Paste

By xiezixing 2026年8月14日

Real Unicode glyphs beat HTML ^{and _{tags when you want chemistry, math exponents, and footnote markers to survive the copy-paste into chat, code, and filenames.}}

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WCAG Contrast Checker Field Guide: Five Numbers That Pass an Accessibility Audit

By xiezixing 2026年8月14日

A WCAG contrast checker is the one accessibility tool that turns subjective design debates into…

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Projectile Motion Field Guide: Five Numbers Your Calculator Already Gives You

By xiezixing 2026年8月14日

If you can plug four numbers into a form, you already know enough to read…

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Upside-Down Text Field Guide: How the Unicode Flip Actually Works

By xiezixing 2026年8月14日

Upside-down text is just per-letter Unicode lookalikes pasted back in reverse order, and that two-step…

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Molar Mass Lookup Field Guide: Atomic Weights That Survive a Lab Bench Audit

By xiezixing 2026年8月14日

Molar mass is just a number — until you ask where it came from. A…

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Remove Duplicate Lines Field Guide: The Five Edge Cases Behind Every “Just Dedup It”

By xiezixing 2026年8月13日

The fastest way to dedupe a long list of lines is rarely a custom script.…

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Mod-11 Checksum Calculator Field Guide: ISBN-10, fodselsnummer, and the X check digit

By xiezixing 2026年8月13日

The Mod-11 check digit is the quiet workhorse behind ISBN-10, ISBT-128 blood bags, Norwegian fødselsnummer,…

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Pressure Calculator & Converter Field Guide: P = F / A and 9 Units in One Tool

By xiezixing 2026年8月13日

The cleanest way to think about pressure is force per unit area, and the cleanest…

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Heading Hierarchy Auditor: A Field Guide to Heading Semantics

By xiezixing 2026年8月13日

The right way to think about heading hierarchy is that visual weight is a side…

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A/B Test Significance Calculator Field Guide 2026-08-12

By xiezixing 2026年8月13日

Stop ending experiment reviews with "p ~= 0.06, ship it" or "5,000 visitors, looks promising"…