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HTML/CSSIntermediate#css#selectors
[attr] matches presence, [attr=val] exact match, [attr^=val] starts with, [attr$=val] ends with, [attr*=val] contains substring. Useful for styling based on HTML attributes without adding classes.
a[target="_blank"] { color: orange; }
input[type="checkbox"] { margin-right: 8px; }
a[href^="https://"]::after { content: ' \2197'; }