value-keyword-case
Specify lowercase or uppercase for keywords values.
    a { display: block; }
/**              ↑
 *    These values */This rule ignores <custom-idents>
of known properties. Keyword values which are paired with non-properties
(e.g. $vars and custom properties), and do not conform to
the primary option, can be ignored using the
ignoreKeywords: [] secondary option.
The fix
option can automatically fix all of the problems reported by this
rule.
Options
string: "lower"|"upper"
"lower"
The following patterns are considered violations:
a {
  display: Block;
}a {
  display: bLoCk;
}a {
  display: BLOCK;
}a {
  transition: -WEBKIT-TRANSFORM 2s;
}The following patterns are not considered violations:
a {
  display: block;
}a {
  transition: -webkit-transform 2s;
}"upper"
The following patterns are considered violations:
a {
  display: Block;
}a {
  display: bLoCk;
}a {
  display: block;
}a {
  transition: -webkit-transform 2s;
}The following patterns are not considered violations:
a {
  display: BLOCK;
}a {
  transition: -WEBKIT-TRANSFORM 2s;
}Optional secondary options
ignoreKeywords: ["/regex/", /regex/, "non-regex"]
Ignore case of keywords values.
For example, with "lower".
Given:
["Block", "/^(f|F)lex$/"]
The following patterns are considered violations:
a {
  display: bLoCk;
}a {
  display: BLOCK;
}a {
  display: fLeX;
}a {
  display: FLEX;
}The following patterns are not considered violations:
a {
  display: block;
}a {
  display: Block;
}a {
  display: flex;
}a {
  display: Flex;
}ignoreProperties: ["/regex/", /regex/, "non-regex"]
Ignore case of the values of the listed properties.
For example, with "lower".
["/^(b|B)ackground$/", "display"];The following patterns are considered violations:
a {
  text-align: LEFT;
}a {
  text-align: Left;
}The following patterns are not considered violations:
a {
  display: bloCk;
}a {
  display: BloCk;
}a {
  display: BLOCK;
}a {
  display: block;
}a {
  background: Red;
}a {
  Background: deepPink;
}ignoreFunctions: ["/regex/", /regex/, "non-regex"]
Ignore case of the values inside the listed functions.
For example, with "upper".
["/^(f|F)oo$/", "t"];The following patterns are considered violations:
a {
  display: b(inline);
}a {
  color: bar(--camelCase);
}The following patterns are not considered violations:
a {
  display: t(flex);
}a {
  display: t(fLeX);
}a {
  color: t(--camelCase);
}a {
  color: foo(--camelCase);
}a {
  color: Foo(--camelCase);
}