Fluid typography with a floor and a ceiling: sizes scale linearly between your min and max viewports and clamp() guarantees they never leave the range. The tool emits both the px form and the rem form, plus the effective size at 320, 768 and 1920 px so you can see the floor and ceiling bite.
The rem form keeps user font-size preferences working: the px in the middle term scales the viewport, the rem endpoints respect the reader.
Frequently asked questions
Why is the rem version more verbose?
It avoids baking a px intercept (which would ignore the user’s root font size); instead it computes the slope as a ratio between the rem endpoints. Verbose, but respects accessibility settings.
Should everything be fluid?
Body copy benefits; tiny labels and buttons usually want fixed sizes — fluid 11-13px UI text often becomes unreadable on phones.
中文说明
带下限与上限的流式字号：字号在最小/最大视口间线性变化，clamp() 保证永不越界。工具同时输出 px 版与 rem 版，并给出 320、768、1920 px 的实际取值，让你看到上下限生效的时刻。
rem 版保留了用户的字号偏好：中项的 px 随视口缩放，两端的 rem 尊重读者设置。
常见问题
为什么 rem 版更长？
它避免写死 px 截距（那会无视用户的根字号），而是用 rem 端点之间的比值表达斜率。啰嗦，但尊重无障碍设置。
所有字号都该流式吗？
正文受益最大；小标签和按钮通常要固定字号——11–13px 的界面文字流式化后在手机上常变得不可读。