def self.builtins
@builtins ||= Set.new %w(
above absolute always armenian aural auto avoid left bottom
baseline behind below bidi-override blink block bold bolder
both bottom capitalize center center-left center-right circle
cjk-ideographic close-quote collapse condensed continuous crop
cross crosshair cursive dashed decimal decimal-leading-zero
default digits disc dotted double e-resize embed expanded
extra-condensed extra-expanded fantasy far-left far-right fast
faster fixed georgian groove hebrew help hidden hide high higher
hiragana hiragana-iroha icon inherit inline inline-table inset
inside invert italic justify katakana katakana-iroha landscape
large larger left left-side leftwards level lighter line-through
list-item loud low lower lower-alpha lower-greek lower-roman
lowercase ltr medium message-box middle mix monospace n-resize
narrower ne-resize no-close-quote no-open-quote no-repeat none
normal nowrap nw-resize oblique once open-quote outset outside
overline pointer portrait px relative repeat repeat-x repeat-y
rgb ridge right right-side rightwards s-resize sans-serif scroll
se-resize semi-condensed semi-expanded separate serif show
silent slow slower small-caps small-caption smaller soft solid
spell-out square static status-bar super sw-resize table-caption
table-cell table-column table-column-group table-footer-group
table-header-group table-row table-row-group text text-bottom
text-top thick thin top transparent ultra-condensed
ultra-expanded underline upper-alpha upper-latin upper-roman
uppercase url visible w-resize wait wider x-fast x-high x-large
x-loud x-low x-small x-soft xx-large xx-small yes
)
end