You're on the right track with your observations! The behavior you're describing with the field in Chrome versus Firefox stems from how browsers handle default styles and input field sizing when min and max attributes are used.

Key Points: Input Width Calculation: By default, browsers try to automatically size the input field based on the possible range of values (i.e., the min and max attributes). This is especially true in Chrome, where the input field’s width may be based on the longest number that can fit between the min and max values. If min and max are not defined, Chrome may default to a generic width that could vary depending on the browser's internal settings.

Browser Differences: Chrome and Firefox tend to have slightly different rendering engines, so they interpret form element sizing in ways that can lead to visual discrepancies. Firefox might not adjust the width of the input field as much as Chrome does, and it could stick to a more fixed or simple size, ignoring the size of the potential numbers.

No min or max Defined: If the min or max attributes are not defined, browsers usually size the input based on what they expect is “good enough” for general use. In many cases, this means using a default width that fits the typical number values.

Conclusion: You are correct that there’s no "objectively correct" size for an input element without any styling. It’s up to the browser to decide, and that's why you're seeing different behavior in Chrome and Firefox.

To have consistent behavior across browsers, it’s a good practice to explicitly define input widths (using CSS) or specify min and max values according to your design needs. This way, you can control the layout and avoid unexpected sizing issues.