jarvus-style-guide.css

css {
    should-look: like-this;
    /* one space after the selector */
    /* opening brace on the same line */
    /* 4-space indent */
    /* closing brace on its own line */
    /* one blank line between rules */
}

.one-liners { can-look: like-this; } /* but only do this if the rule has only one property and it's unlikely to gain more */

grouped,
selectors {
    go: 'on separate lines'; /* single quotes around strings in CSS and JS, double quotes for HTML attributes */
}

colors {
    use: #b4d455; /* lowercase alpha digits */
    use: #cdc;    /* three-digit hex if it's available */
    use: white;   /* keyword if it's common */
}

sort {
    all: properties;
    in: alphabetical;
    order: for-sanity;
}

div {
    /* always use the shortest notation possible for box-model lengths */
    /* remember that bottom will copy top and left will copy right, unless otherwise indicated */
    /* also, leave units off zero values */
    border-radius: 2px;           /* not 2px 2px 2px 2px */
    border-width: 1px 0;          /* not 1px 0px 1px 0px */
    margin: 10px 20px 30px;       /* not 10px 20px 30px 20px; */
    padding: 10px 20px 30px 40px; /* write out all four only if necessary */
}

div {       
    /* sometimes it's more readable to declare an all-around value and then "tweak" it */
    /* this makes the outlier stand out better */
    padding: 10px;
    padding-right: 0;
    /* not padding: 10px 0 10px 10px */
    /* but this is not a hard and fast rule */
}

Another one:

• Avoid using shorthand for things like background, where there are a bunch of values that you might be inadvertently overwriting by omission. Use the individual properties instead to avoid cascade weirdness.