app-reset.css

/*
# App reset by Ben Frain @benfrain / benfrain.com

An opinionated set of resets suitable for building web applications.

Latest: https://github.com/benfrain/app-reset

# Accessibility Notes
These resets target HTML elements that typically receive styling defaults by User Agents that I always need to 'undo'.

Be aware that some of these resets have a negative impact on the default usability and accessibility of a web page. Therefore, ensure you add an equivalent accessible style back that matches your project aesthetic.

You may want to run this through Autoprefixer (https://github.com/postcss/autoprefixer) for production. 
*/

/* Allows height/width animations to auto across document */
:root {
    interpolate-size: allow-keywords;
}

html {
    /*Hat tip to @thierrykoblentz for this approach: https://css-tricks.com/inheriting-box-sizing-probably-slightly-better-best-practice/ */
    box-sizing: border-box;
    --fontStack: -apple-system, BlinkMacSystemFont, "Helvetica Neue", "Segoe UI",
        Tahoma, Roboto, Oxygen, Ubuntu, Cantarell, "Fira Sans", "Open Sans",
        sans-serif;
    font-family: var(--fontStack);
}

/*Yes, the universal selector. No, it isn't slow: https://benfrain.com/css-performance-revisited-selectors-bloat-expensive-styles/*/
* {
    /*This prevents users being able to select text. Stops long presses in iOS bringing up copy/paste UI for example*/
    user-select: none;
    /* Most devs find border-box easier to reason about. However by inheriting we can mix box-sizing approaches.*/
    box-sizing: inherit;
}

*:before,
*:after {
    box-sizing: inherit;
}

body,
h1,
h2,
h3,
h4,
h5,
h6,
p {
    /*We will be adding our own margin to these elements as needed.*/
    margin: 0;
    /*You'll want to set font-size as needed.*/
    font-size: 1rem;
    /*No bold for h tags unless you want it*/
    font-weight: 400;
}

a {
    text-decoration: none;
    color: inherit;
}

/*No bold for b tags by default*/
b {
    font-weight: 400;
}

/*Prevent these elements having italics by default*/
em,
i {
    font-style: normal;
}

/*IMPORTANT: This removes the focus outline for most browsers. Be aware this is a backwards accessibilty step!*/
a:focus,
button:focus {
    outline: 0;
}

/* The button element tends to get a lot of default styles which we largely undo here. We set text-alignment (usually set to center by UA style sheet) and the font-family to inherit from your own styles instead. */
button {
    appearance: none;
    background-color: transparent;
    border: 0;
    padding: 0;
    text-align: inherit;
    font-family: inherit;
    font-weight: inherit;
    font-size: inherit;
    /* Safari adds margin */
    margin: 0;
}

button:hover {
    cursor: pointer;
}

input,
fieldset {
    appearance: none;
    border: 0;
    padding: 0;
    margin: 0;
    /*inputs and fieldset defaults to having a min-width equal to its content in Chrome and Firefox (https://code.google.com/p/chromium/issues/detail?id=560762), we may not want that*/
    min-width: 0;
    /*Reset the font size and family*/
    font-size: inherit;
    font-family: inherit;
}

/*This switches the default outline off when an input receives focus (really important for users tabbing through with a keyboard) so ensure you put something decent in for your input focus instead!!*/
input:focus {
    outline: 0;
}

/*Removes the little spinner controls for number type inputs (WebKit browsers/forks only)*/
input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button {
    appearance: none;
}

/*SVG defaults to display: inline which I dislike. Inline-block or inline-flex will render white space on SVG elements in HTML (where you would have defs and symbols) if the container isn't a flex box or the font-size set to 0 to crush the whitespace */
svg {
    display: block;
}

img {
    /*Make images behave responsively. Here they will scale up to 100% of their natural size*/
    max-width: 100%;
    /*Make images display as a block (UA default is usually inline)*/
    display: block;
}

/* Switching on box-sizing: border-box by default; toggle this off if you want more granular control */
body {
    box-sizing: border-box;
}