UserAgent.me

What Does Your User Agent Say About You?

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A user agent is a computer program representing a person, for example, a browser in a Web context.

Besides a browser, a user agent could be a bot scraping webpages, a download manager, or another app accessing the Web. Along with each request they make to the server, browsers include a self-identifying User-Agent HTTP header called a user agent (UA) string. This string often identifies the browser, its version number, and its host operating system.

Spam bots, download managers, and some browsers often send a fake UA string to announce themselves as a different client. This is known as user agent spoofing.

The user agent string can be accessed with JavaScript on the client side using the navigator.userAgent property.

A typical user agent string looks like this: "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:35.0) Gecko/20100101 Firefox/35.0".

(Source: Mozilla.org)

User Agent String

Browser Data

User Agent Stylesheet Button

author
Maria Johnson
• Saturday, 24 October, 2020
• 11 min read

Peter Mortensen 27.2k2121 gold badges9393 silver badges123123 bronze badges If is missing in your HTML content you may experience that the browser gives preference to the useragentstylesheet over your custom stylesheet.

stylesheet agent user css basics webpage applied resets emmet
(Source: www.codingexercises.com)

Contents

Peter Mortensen 27.2k2121 gold badges9393 silver badges123123 bronze badges Regarding the concept user agent style sheet”, consult section Cascade in the CSS 2.1 spec.

They are just the rock bottom: in the absence of any style sheets provided by the page or by the user, the browser still has to render the content somehow, and the user agent style sheet just describes this. Marking the document as HTML5 by the proper doc type on the first line, solved my issue.

In order to present the page in a way that satisfies ” general presentation expectations.” For example, a default style sheet would provide base styles for things like font size, borders, and spacing between elements. It is common to employ a reset style sheet to deal with inconsistencies amongst browsers.

Peter Mortensen 27.2k2121 gold badges9393 silver badges123123 bronze badges Each browser provides a default stylesheet, called the useragentstylesheet, in case an HTML file does not specify one.

I had a dumb error where a button element didn't look right in Chrome. So Chrome was stepping in to supply the parts that it thought I was missing.

css button border tricks overriding chrome buttons corners curved shadow drop
(Source: css-tricks.com)

Peter Mortensen 27.2k2121 gold badges9393 silver badges123123 bronze badges In Chrome developer tools, it says useragentstylesheet in place of the CSS file name.

CSS takes care of default formatting of documents through the concept of user agent style sheets, a cornerstone of the cascade. It means that a web browser doesn’t just present a line of text when it’s fed with an HTML document that has no styling information attached, but instead serves it using minimal formatting.

The following is a list of default style sheets I’ve compiled over recent years (except for Safari; thank you, Martin). Due to the fact that Fire bird, Firefox, and Co. are all based on the same layout engine, they’re quite similar, if not identical.

As in, they just reach for whatever generic, styling-free HTML is handy and build it up as needed. That doesn’t mean you should attach your JavaScript events to a

or an though.

I feel like the answer to this is basically a big of’ block of CSS. That’s what Andy provided, and you could very likely come to one on your own by just being a little heavier handed than the usual of setting style rules with your buttons.

(Source: mebee.info)

Still, I felt compelled to make a little tester machine thingy so you can toggle styles on and off and see how they all go together in whatever browser you happen to be in: The biggest point here is to use the correct native elements, as you get a bunch of functionality and accessibility for free.

I'm developing a website and trying to debug in Chrome dev tool. On Chrome dev tool it says Sergeant style instead of CSS file.

In order to present the page in a way that satisfies ” general presentation expectations.” For example, a default style sheet would provide base styles for things like font size, borders, and spacing between elements. It is common to employ a reset style sheet to deal with inconsistencies among browsers.

For this create CSS class and override the agent style sheet. To clarify, my question is about why the useragentstylesheet is overriding the CSS and how to make that stop.

Becerra Beterraba6,31011 gold badge2323 silver badges3333 bronze badges This allows the behavior I originally expected to happen in all cases where the user agent would otherwise cause the style not to inherit.

(Source: magnet88jp.hateblo.jp)

Answering this question generally with elaborating the explanation I would say, the final value of CSS property is a four-step calculation (i.e. In specification, Cascading takes precedence over Inheritance.

The conflicting declarations will be applied in the following order; later ones will override earlier ones: In above code since you only have user agent style sheet bounded with the element directly, hence takes precedence.

In short inheritance < cascading < importance < useragentstylesheet is precedence order in your case. This behavior is seen in Chrome only (it is not in Firefox, I didn't test Edge or others).

Chrome applies a pale yellow background (#E8F0FE) Today I got the same issue, tested with no such pale-effect on Safari and Brave... Not sure why the so-long-waiting (3 years and counting) from Chrome to come up with a fix.

I thought I had this problem and checked the usual suspects, Doc type, etc. As ridiculous as this sounds, it turned out the style which I thought was being applied was commented out in the CSS.

(Source: teratail.com)

I'm working on a web app that has a poplar similar to Facebook's blue bar at the top. The UL has a 1em margin as defined by the useragentstylesheet of my browser.

The issue is that the OP did not pick a rule that could possibly override the margin property that is set by the Sergeant (UA) directly on the UL tag. Inheritance is the means by which, in the absence of any specific declarations from any source applied by the CSS cascade, a property value of an element is obtained from its parent element.

This is a better attempt, a more specific selector #Vienna, which matches the Vienna element lower in the DOM, but the same principle applies, because the UL element is still below this element in the DOM. So, assuming that the UA rule used the selector UL and not !important, which is most likely the case, the solution would have been a simple UL {margin: 0;} , but it would be safer to make it more specific, say #Vienna UL {margin: 0} .

Sevenseacat sevenseacat23k55 gold badges5858 silver badges8383 bronze badges Making statements based on opinion; back them up with references or personal experience.

Making statements based on opinion; back them up with references or personal experience. The color-scheme CSS property and the corresponding meta tag allow developers to opt their pages in to the theme-specific defaults of the useragentstylesheet.

stylesheet agent user
(Source: www.youtube.com)

One puzzle piece that was only mentioned briefly in the article is the color-scheme CSS property and the corresponding meta tag of the same name. They both make your life as a developer easier by allowing you to opt your page in to theme-specific defaults of the useragentstylesheet, such as, for example, form controls, scroll bars, as well as CSS system colors.

You can have a look at Chrome's (and Chromium's) UA stylesheet and compare it to Firefox's or Safari's (and WebKit's). For example, they all make links blue, general text black, and background color white, but there are also important (and sometimes annoying) differences, for instance, how they style form controls.

To illustrate this, here is one such CSS rule using the :matches pseudo class and WebKit-internal variables like -apple-system-control-background, as well as the WebKit-internal preprocessor directive #if defined : UA stylesheets can use either their own proprietary or the standardized semantic system colors, to determine how HTML elements should be rendered by default.

The UA stylesheet then assigns the following CSS only once, and covers both light and dark mode. The color-scheme property defined therein allows an element to indicate which color schemes it is comfortable being rendered with.

+ Indicates that the element is aware of and can handle the listed color schemes, and expresses an ordered preference between them. Warning: Previously, the specification allowed an additional value light only that indicated that the element had to be rendered with a light color scheme if possible, even if the user's preference is for a different color scheme.

button css background styles overriding tricks
(Source: css-tricks.com)

Authors should not use this value, and should instead ensure their page renders well with whatever color scheme the user prefers. Examples are scroll bars, spellcheck underlines, form controls, etc.

To aid user agents in rendering the page background with the desired color scheme immediately, a color-scheme value can also be provided in a element. Since both the meta tag and the CSS property (if applied to the :root element) eventually result in the same behavior, I always recommend specifying the color scheme via the meta tag, so the browser can adapt to the preferred scheme faster.

While for absolute baseline pages no additional CSS rules are necessary, in the general case you should always combine color-scheme with prefers-color-scheme. For example, the proprietary WebKit CSS color -webkit-link, used by WebKit and Chrome for the classic link blue RGB(0,0,238), has an insufficient contrast ratio of 2.23:1 on a black background and fails both the Wag AA and the Wag AAA requirements.

The interplay of the color-scheme CSS property and the corresponding meta tag with the prefers-color-scheme user preference media feature may seem confusing at first. The inline CSS code on the page sets the element's background-color to Greensboro in the general case, and to darkslategray if the user prefers a dark color scheme according to the prefers-color-scheme user preference media feature.

There is no additional developer-provided CSS involved to change the paragraph text or the background color of the page. Note how the element's background-color changes based on whether dark mode is enabled, following the rules in the developer-provided inline stylesheet on the page.

user agent choose css tuesdays agents fun
(Source: www.jappler.com)

Light mode: The computed values of the border-top-color and the border-bottom-color that are both set to Buttonhole in the useragentstylesheet are now RGBA(0, 0, 0, 0.847). Dark mode: The computed values of the border-top-color and the border-bottom-color that are both set to Buttonhole in the useragentstylesheet are now RGBA(255, 255, 255, 0.847).

You can see the effects of color-scheme applied to many HTML elements in a demo on Glitch. The color-scheme CSS property and the corresponding meta tag were implemented by Rune Lillesveen.

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02: Wireshark Filter User Agent
03: Wireshark Find User Agent
Sources
1 ask.wireshark.org - https://ask.wireshark.org/question/15831/how-to-find-user-agent-string-in-wireshark/
2 unit42.paloaltonetworks.com - https://unit42.paloaltonetworks.com/using-wireshark-identifying-hosts-and-users/
3 osqa-ask.wireshark.org - https://osqa-ask.wireshark.org/questions/9321/browser-user-agent
4 serverfault.com - https://serverfault.com/questions/646063/user-agent-in-http-or-https-request
5 www.wireshark.org - https://www.wireshark.org/docs/wsug_html/
6 www.wireshark.org - https://www.wireshark.org/docs/dfref/h/http.html
7 developer.mozilla.org - https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/User-Agent
8 ask.wireshark.org - https://ask.wireshark.org/questions/scope:unanswered/sort:age-desc/tags:homework,string,agent,user/page:1/