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Explain rem, px and em
In web design, rem, px, and em are units of measurement used for CSS properties, especially for font sizes and spacing.
px (pixels): This is a fixed unit. If you set an element's width to 100px, it will always be 100 pixels wide, regardless of the user's settings or screen size. It's precise but not scalable.
em: This unit is relative to the font size of its parent element. If you set an element's font size to 2em, it will be twice the size of its parent element's font size. For example, if the parent font size is 16px, 2em would equal 32px. This is useful for creating responsive designs.
rem (root em): Similar to em, but it is relative to the root (html) font size. It provides a more consistent sizing because it doesn't depend on the parent element's size. If the root font size is 16px and you set an element's size to 2rem, it will be 32px.
Here's an example in CSS:
css Copy code
body {
font-size: 16px; /* root font size */
}
h1 {
font-size: 2rem; /* 2 * 16px = 32px */
}
p {
font-size: 1.5em; /* if parent font size is 20px, then 1.5em = 30px */
}
footer {
font-size: 14px; /* parent size for example */
}
footer p {
font-size: 1em; /* 1 * 14px = 14px because this is relative to footer */
}
In this example, the h1 will always be twice the root size, while the p elements will vary depending on their parent size.
what does rem in css mean?
rem stands for "root em" and it is a relative unit of measurement in CSS. It is based on the font-size of the root element (typically the <html> tag).
Unlike the em unit, which is relative to its parent element, rem is always relative to the root element. This means that if the root element has a font-size of 16 pixels, then 1 rem is equal to 16 pixels.
The use of rem allows for more consistent and scalable designs, especially when it comes to responsive web development. Instead of specifying sizes using fixed pixels, rem can be used to create flexible and adaptable layouts.
Here's an example:
css Copy code
html {
font-size: 16px;
}
p {
font-size: 1.5rem; /* This would be equivalent to 24 pixels (1.5 * 16) */
}
With this example, even if the font-size of the root element changes, the p element will always be 1.5 times the size of the root element's font-size.
can you explain the difference between em and rem in css
In CSS, em and rem are units of measurement for font sizes or other element sizes.
em stands for "em height" and is relative to the font size of its closest parent element. For example, if the font size of a parent element is 16 pixels, then 1em would be equal to 16 pixels. If you set the font size of a child element to 0.5em, it would be half the size of its parent's font size.
rem stands for "root em" and is similar to em, but it is relative to the root element (usually the <html> element). This means that the font size of a rem unit is relative to the base font size of the document, which is often set to 16 pixels by default. For example, if the base font size is 16 pixels, then 1rem would be equal to 16 pixels. If you set the font size of a child element to 0.5rem, it would be half the size of the base font size.
Here's an example to illustrate the difference:
css Copy code
.parent {
font-size: 16px;
}
.child-em {
font-size: 1em; /* equal to 16px, relative to parent font size */
}
.child-rem {
font-size: 1rem; /* equal to 16px, relative to base font size */
}
In this example, both .child-em and .child-rem have the same font size, but their sizes are determined differently. The .child-em font size of 1em is relative to its parent's font size, while .child-rem font size of 1rem is relative to the base font size.
is it best to use px rem or em when spacing between elements
When setting the spacing between elements, the best option to use depends on the context of your project.
px is a fixed unit of measurement and is not affected by the size of the browser viewport or the base font size defined for the project. This makes it ideal for smaller elements such as buttons.
rem is a relative unit that is based on the root elementβs font-size. It's good to use for larger components like headers, as it adjusts in size in accordance with the base font size.
em is also a relative unit and is based on the font size of the parent element. It's good for context-specific sizing of elements.
You can also use a combination of these units depending on the different elements in your project to achieve the desired spacing.
Here is an example of using rem for a margin of 20 pixels:
css Copy code
.my-class {
margin: 1.25rem; /* assuming the root font-size is 16px */
}
when is best practice to use ems rems and px
When deciding between using em, rem, or px for sizing, it's best to consider the needs of your design and accessibility.
px when you need fixed-size elements that won't change, such as for borders or shadows.rem for font sizes to make it more accessible to users who have changed their browser's default font size. rem is relative to the root font size or default font size of the browser.em when you need to set a size relative to its parent, such as for a button that needs to grow or shrink within its container. em is relative to its parent element's font size. It's important to keep in mind that using relative units like em and rem ensures that your design remains consistent and adaptable to different screen sizes and user preferences. For more information, you can check out this article about responsive typography using rem and em: https://www.smashingmagazine.com/2017/07/enhancing-typographic-hierarchy-with-css-rem-and-em-values/
when to use em rem and px
When it comes to styling elements on a webpage, there are a number of ways to define font size including using em, rem, and px. Here is a brief explanation of how and when to use each unit:
px (pixels) is an absolute unit and it sets the font size of an element to a specific number of pixels. This unit is often used for small font sizes or specific design requirements, but it can be problematic for accessibility because users may have trouble resizing text on some devices.Example (CSS):
code Copy code
p {
font-size: 16px;
}
em is a relative unit that is based on the parent element's font size. This is useful for proportional scaling of elements. For example, if a parent element has a font size of 16px and the child element is set to 2em, the font size would be 32px.Example (CSS):
code Copy code
.parent {
font-size: 16px;
}
.child {
font-size: 2em; /* 32px */
}
rem is another relative unit that is based on the root element's font size. This allows for consistent scaling across all elements on a webpage, regardless of the context. It can be particularly useful for responsive design.Example (CSS):
code Copy code
html {
font-size: 16px;
}
.element {
font-size: 1.25rem; /* 20px */
}
Overall, em and rem are more flexible and adaptable than px. It's a good idea to consider the context and requirements of your design when choosing which unit of measure to use.
how many px is 2rem
2rem is equivalent to the computed value of font-size of the root element. It is a relative unit of measurement, so different browsers and devices interpret it differently. To calculate the exact number of pixels, use the following equation: px = rem * root font size. For example, if the root font size is 16px, 2rem is equal to 32px (2*16 = 32).
why is my font using rem and not updating
Your font size may not be updating since you are using rem units instead of px units. rem units are based on the root element's (most commonly the <html> element) font size; using rem ensures that the element will automatically scale up or down relative to the <html> element. If your font size is not updating, you may need to edit the <html> element's font size. Depending on which stylesheet language you are using, you may need to use:
font-size: 16px;
html { font-size: 16px; }
@html-font-size: 16px;
why does my font size say rem
Rem stands for "root em" which is a unit of measurement used in CSS (Cascading Style Sheets) to determine the size of a font relative to the size of the root element. It is calculated as a ratio between the font size of the root element and the final font size. For example, if the root element size of 16px and font size of 0.8rem is used, the final font size would end up being 12.8 px. For more information, refer to this article from W3 Schools: https://www.w3schools.com/cssref/css_units.asp
what is rem in css
In Css, rem stands for "root em". It is a unit of measurement used to define sizes relative to the font size set on the root element of the document. In other words, it is a font size relative to the root element of the document. For example, if an element has a font size of 16px and is set to rem, the font size is set to 1rem, or 16px. rem can also be used to set the size for other elements and makes it easier to manage elements across different devices and screen sizes. For example, if you set the font size of the root element to 16px, 1.2rem will be equivalent to 19.2px, regardless of the device or screen size. More information on rem can be found here.
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