5.3.1 / 2022-07-13

• Fixed issue #1218 - double hyphen in at-rule breaks parsing.
• Fixed issue #1220 - adds optimization for nth-* rules.

5.3.0 / 2022-03-31

• Adds customizable value optimizers for variables.
• Fixed issue #1159 - adds optimization for nth-child and nth-of-type.
• Fixed issue #1181 - CSS level 4 color functions with spaces.
• Fixed issue #1183 - fraction optimizer breaks image-set.
• Fixed issue #1208 - handling generic family names.
• Fixed issue #1210 - handling file:// protocol.

5.2.4 / 2022-01-28

• Fixed issue #1196 - correctly parse variables & comments mix.

5.2.3 / 2022-01-26

• Fixed issue #1185 - keeping comments inside variables.
• Fixed issue #1194 - unexpected end of JSON input when source map is empty.

5.2.2 / 2021-10-21

• Fixed an unsafe data URI regex, which, when clean-css is used as a service, could be used in a DOS attack.

5.2.1 / 2021-09-30

• Fixed issue #1186 - bad error handling in batch mode with promises.

5.2.0 / 2021-09-25

• Fixed issue #1180 - properly handle empty variable values.

5.1.5 / 2021-08-05

• Fixed issue #1178 - fixes lack of space removal in variable blocks.

5.1.4 / 2021-07-29

• Fixed issue #1177 - fix to missing local imports when only remote ones allowed.

5.1.3 / 2021-06-25

• Fixed issue #1160 - keep zero units when inside multiple functions.
• Fixed issue #1161 - extra whitespace in URLs.
• Fixed issue #1166 - incorrect compoment splitting when empty multiplex part.

5.1.2 / 2021-03-19

• Fixed issue #996 - space removed from pseudo classes.

5.1.1 / 2021-03-03

• Fixed issue #1156 - invalid hsl/hsla validation in level 2 optimizations.

5.1.0 / 2021-02-18

• Fixes stripping '%' from inside color functions.
• Improves tokenization speed by ~30%.
• Fixed issue #1143 - some missing level 1 value optimizations.

5.0.1 / 2021-01-29

• Fixed issue #1139 - overriding & merging properties without canOverride set.

5.0.0 / 2021-01-29

• Adds a way process input files without bundling it into one big output file.
• Adds level 1 and level 2 optimization plugins.
• Disables URL rebasing by default.
• Disables URL unquoting by default.
• Drops support for Node.js 6 & 8 to support last 3 Node.js releases: 10, 12, and 14.
• Fixed issue #889 - whitelisted level 1 optimizations.
• Fixed issue #975 - incorrect block name optimization.
• Fixed issue #1009 - whitespace around comments.
• Fixed issue #1021 - allow one- and two-letter property names.
• Fixed issue #1022 - merging into shorthands new property positioning.
• Fixed issue #1032 - wrong order of merged shorthands with inherit.
• Fixed issue #1043 - calc fallback removed within other function.
• Fixed issue #1045 - non-standard protocol-less URL first slash removed.
• Fixed issue #1050 - correctly keeps default animation duration if delay is also set.
• Fixed issue #1053 - treats calc() as first class width value.
• Fixed issue #1055 - supports 4- and 8-character hex with alpha color notation.
• Fixed issue #1057 - level 2 optimizations and quoted font family name.
• Fixed issue #1059 - animation time units as CSS expressions.
• Fixed issue #1060 - variable removed when shorthand's only value.
• Fixed issue #1062 - wrong optimization of CSS pseudo-classes with selector list.
• Fixed issue #1073 - adds support for non-standard rpx units.
• Fixed issue #1075 - media merging and variables.
• Fixed issue #1087 - allow units with any case.
• Fixed issue #1088 - building source maps with source preserved via comments.
• Fixed issue #1090 - edge case in merging for border and border-image.
• Fixed issue #1103 - don't allow merging longhand into unset shorthand.
• Fixed issue #1115 - incorrect multiplex longhand into shorthand merging.
• Fixed issue #1117 - don't change zero values inside min, max, and clamp functions.
• Fixed issue #1122 - don't wrap data URI in single quotes.
• Fixed issue #1125 - quotes stripped from withing @supports clause.
• Fixed issue #1128 - take variables into account when reordering properties.
• Fixed issue #1132 - vendor-prefixed classes inside :not().
• Reworks all level 1 optimizations to conform to plugin style.

4.2.3 / 2020-01-28

• Fixed issue #1106 - regression in handling RGBA/HSLA colors.

4.2.2 / 2020-01-25

• Fixed error when property block has no value.
• Fixed issue #1077 - local fonts with color in name.
• Fixed issue #1082 - correctly convert colors if alpha >= 1.
• Fixed issue #1085 - prevent unquoting of grid elements.

4.2.1 / 2018-08-07

• Fixes giving breakWith option via a string.

4.2.0 / 2018-08-02

• Adds process method for compatibility with optimize-css-assets-webpack-plugin.
• Fixed issue #861 - new transition property optimizer.
• Fixed issue #895 - ignoring specific styles.
• Fixed issue #947 - selector based filtering.
• Fixed issue #964 - adds configurable line breaks.
• Fixed issue #986 - level 2 optimizations and CSS 4 colors.
• Fixed issue #1000 - carriage return handling in tokenizer.
• Fixed issue #1038 - font-variation-settings quoting.
• Fixes ReDOS vulnerabilities in validator code.

4.1.11 / 2018-03-06

• Backports fixes to ReDOS vulnerabilities in validator code.

4.1.10 / 2018-03-05

• Fixed issue #988 - edge case in dropping default animation-duration.
• Fixed issue #989 - edge case in removing unused at rules.
• Fixed issue #1001 - corrupted tokenizer state.
• Fixed issue #1006 - edge case in handling invalid source maps.
• Fixed issue #1008 - edge case in breaking up font shorthand.

4.1.9 / 2017-09-19

• Fixed issue #971 - edge case in removing unused at rules.

4.1.8 / 2017-09-02

• Fixed issue #959 - regression in shortening long hex values.
• Fixed issue #960 - better explanation of efficiency stat.
• Fixed issue #965 - edge case in parsing comment endings.
• Fixed issue #966 - remote @imports referenced from local ones.

4.1.7 / 2017-07-14

• Fixed issue #957 - 0% minification of width property.

4.1.6 / 2017-07-08

• Fixed issue #887 - edge case in serializing comments.
• Fixed issue #953 - beautify breaks attribute selectors.

4.1.5 / 2017-06-29

• Fixed issue #945 - hex RGBA colors in IE filters.
• Fixed issue #952 - parsing @page according to CSS3 spec.

4.1.4 / 2017-06-14

• Fixed issue #950 - bug in removing unused @font-face rules.

4.1.3 / 2017-05-18

• Fixed issue #946 - tokenizing -ms-grid-columns repeat syntax.

4.1.2 / 2017-05-10

• Fixed issue #939 - semicolon after @apply at rule.
• Fixed issue #940 - handling more font keywords.
• Fixed issue #941 - breaking up vendor prefixed animation.

4.1.1 / 2017-05-08

• Fixed issue #938 - removing unused at-rules with !important.

4.1.0 / 2017-05-07

• Improves longhand-into-shorthand merging mechanism in complex cases as with border-* shorthands.
• Fixed issue #254 - adds font property optimizer.
• Fixed issue #525 - restores inherit-based merging.
• Fixed issue #755 - adds custom handling of remote requests.
• Fixed issue #860 - adds animation property optimizer.
• Fixed issue #862 - allows removing unused at rules.
• Fixed issue #886 - better multi pseudo class / element merging.
• Fixed issue #890 - adds toggle to disable empty tokens removal.
• Fixed issue #893 - inline: false as alias to inline: 'none'.
• Fixed issue #905 - allows disabling selector sorting.
• Fixed issue #906 - improves usability of web UI settings.
• Fixed issue #908 - improved minify method signature.
• Fixed issue #916 - maximum number of merged selectors.
• Fixed issue #920 - allows skipping certain properties in level 2 optimizations.
• Fixed issue #934 - smarter longhand into shorthand merging.

4.0.13 / 2017-05-10

• Backports #939 - semicolon after @apply at rule.

4.0.12 / 2017-04-12

• Fixed issue #930 - regression in tidying selectors.

4.0.11 / 2017-04-04

• Fixed issue #924 - hsl zero percent eager optimization.

4.0.10 / 2017-03-22

• Fixed issue #917 - prevents grid area unquoting.
• Backported #916 - maximum number of merged selectors.
• Refixed issue #556 - IE backslash hacks.

4.0.9 / 2017-03-15

• Fixed issue #902 - case insensitive attribute matchers.
• Fixed issue #903 - web UI and source maps.
• Fixed issue #907 - space after closing brace in @supports.
• Fixed issue #910 - too aggressive precision optimizations.

4.0.8 / 2017-02-22

• Fixes edge case in remote stylesheet fetching.
• Fixed issue #899 - regression in optimizing pseudo class arguments.

4.0.7 / 2017-02-14

• Fixed issue #891 - merging vendor-prefixed pseudo-classes.

4.0.6 / 2017-02-10

• Fixed issue #885 - unquoting font-feature-settings.

4.0.5 / 2017-02-07

• Fixed issue #884 - handling absolute paths on Windows.
• Fixed issue #881 - incorrect require arity.
• Fixed issue #880 - incorrect token type identification.

4.0.4 / 2017-02-04

• Fixed issue #879 - incorrect handling of spaces in paths.
• Fixed issue #878 - invalid double backslash tokenization.

4.0.3 / 2017-01-30

• Fixed issue #875 - invalid traversing in semantic merging.

4.0.2 / 2017-01-26

• Fixed issue #874 - regression in at-rule tokenization.

4.0.1 / 2017-01-25

• Fixed issue #866 - edge case in inline option.
• Fixed issue #867 - skip optimizing variable values.
• Fixed issue #868 - accept absolute paths in input hash.
• Fixed issue #872 - edge case in CSS tokenization.

4.0.0 / 2017-01-23

• Adds more detailed error & warning messages on top of the new tokenizer.
• Disables restructuring optimizations by default until optimized in #533.
• Fixes a bug ignoring incorrect properties in complex restructuring.
• Requires Node.js 4.0+ to run.
• Removes benchmark API option as total time is always reported under stats property.
• Removes debug API switch as stats are always gathered and available under stats property.
• Replaces the old tokenizer with a new one which doesn't use any escaping.
• Replaces the old @import inlining with one on top of the new tokenizer.
• Re-enables background-(clip|origin|size) merging with background shorthand.
• Simplifies URL rebasing with a single rebaseTo option in API or inferred from --output in CLI.
• Splits inliner option into inlineRequest and inlineTimeout.
• Fixed issue #209 - adds output formatting via format flag.
• Fixed issue #290 - removes aggressive merging.
• Fixed issue #432 - adds URLs normalization.
• Fixed issue #460 - unescaped semicolon in selector.
• Fixed issue #657 - adds property name validation.
• Fixed issue #685 - adds lowercasing hex colors optimization.
• Fixed issue #686 - adds rounding precision for all units.
• Fixed issue #703 - changes default IE compatibility to 10+.
• Fixed issue #731 - adds granular control over level 2 optimizations.
• Fixed issue #739 - error when a closing brace is missing.
• Fixed issue #750 - allows width overriding.
• Fixed issue #756 - adds disabling font-weight optimizations.
• Fixed issue #758 - ignores rules with empty selector.
• Fixed issue #767 - disables remote @import inlining by default.
• Fixed issue #773 - adds reordering based on selector specificity.
• Fixed issue #785 - adds @font-face de-duplication.
• Fixed issue #791 - resolves imports in-memory if possible.
• Fixed issue #796 - semantic merging for @media blocks.
• Fixed issue #801 - smarter @import inlining.
• Fixed issue #806 - skip optimizing variable properties.
• Fixed issue #817 - makes off disable rounding.
• Fixed issue #818 - disables px rounding by default.
• Fixed issue #828 - -chrome- hack support.
• Fixed issue #829 - adds more strict selector merging rules.
• Fixed issue #834 - adds extra line break in nested blocks.
• Fixed issue #836 - enables level 0 optimizations.
• Fixed issue #839 - allows URIs in import inlining rules.
• Fixed issue #840 - allows input source map as map object.
• Fixed issue #843 - regression in selector handling.
• Fixed issue #845 - web compatibility of 4.0 branch.
• Fixed issue #847 - regression in handling invalid selectors.
• Fixed issue #849 - disables inlining protocol-less resources.
• Fixed issue #856 - allows minify to return a promise.
• Fixed issue #857 - normalizes CleanCSS API interface.
• Fixed issue #863 - adds transform callback for custom optimizations.

3.4.26 / 2017-05-10

• Backports #939 - semicolon after @apply at-rule.

3.4.25 / 2017-02-22

• Fixed issue #897 - tokenization with escaped markers.

3.4.24 / 2017-01-20

• Fixed issue #859 - avoid -webkit-border-radius optimizations.

3.4.23 / 2016-12-17

• Fixed issue #844 - regression in property values extraction.

3.4.22 / 2016-12-12

• Fixed issue #841 - disabled importing and files passed as array.
• Ignores @import at-rules if appearing after any non-@import rules.

3.4.21 / 2016-11-16

• Fixed issue #821 - reducing non-adjacent rules.
• Fixed issue #830 - reordering border-* properties.
• Fixed issue #833 - moving @media queries.

3.4.20 / 2016-09-26

• Fixed issue #814 - :selection rule merging.

3.4.19 / 2016-07-25

• Fixed issue #795 - !important and override compacting.

3.4.18 / 2016-06-15

• Fixed issue #787 - regression in processing data URIs.

3.4.17 / 2016-06-04

• Fixed issue #783 - regression in processing data URIs.

3.4.16 / 2016-06-02

• Fixed issue #781 - regression in override compacting.
• Fixed issue #782 - regression in processing data URIs.

3.4.15 / 2016-06-01

• Fixed issue #776 - edge case in quoted data URIs.
• Fixed issue #779 - merging background-(position|size).
• Fixed issue #780 - space after inlined variables.

3.4.14 / 2016-05-31

• Fixed issue #751 - stringifying CSS variables.
• Fixed issue #763 - data URI SVG and quoting.
• Fixed issue #765 - two values of border-radius.
• Fixed issue #768 - invalid border-radius property.

3.4.13 / 2016-05-23

• Fixed issue #734 - Node.js 6.x support.

3.4.12 / 2016-04-09

• Fixed issue #734 - --root option edge case.
• Fixed issue #758 - treats empty rule as unmergeable.

3.4.11 / 2016-04-01

• Fixed issue #738 - edge case in comment processing.
• Fixed issue #741 - HTTP proxy with HTTPS inlining.
• Fixed issue #743 - background shorthand and source maps.
• Fixed issue #745 - matching mixed case !important.

3.4.10 / 2016-02-29

• Fixed issue #735 - whitespace removal with escaped chars.

3.4.9 / 2016-01-03

• Sped up merging by body advanced optimization.
• Fixed issue #693 - restructuring edge case.
• Fixed issue #711 - border fuzzy matching.
• Fixed issue #714 - stringifying property level at rules.
• Fixed issue #715 - stack too deep in comment scan.

3.4.8 / 2015-11-13

• Fixed issue #676 - fuzzy matching unqoted data URIs.

3.4.7 / 2015-11-10

• Fixed issue #692 - edge case in URL quoting.
• Fixed issue #695 - shorthand overriding edge case.
• Fixed issue #699 - IE9 transparent hack.
• Fixed issue #701 - url quoting with hash arguments.

3.4.6 / 2015-10-14

• Fixed issue #679 - wrong rebasing of remote URLs.

3.4.5 / 2015-09-28

• Fixed issue #681 - property inheritance & restructuring.
• Fixed issue #675 - overriding with !important.

3.4.4 / 2015-09-21

• Fixed issue #626 - edge case in import rebasing.
• Fixed issue #674 - adjacent merging order.

3.4.3 / 2015-09-15

• Fixed issue #668 - node v4 path.join.
• Fixed issue #669 - adjacent overriding with !important.

3.4.2 / 2015-09-14

• Fixed issue #598 - restructuring border properties.
• Fixed issue #654 - disables length optimizations.
• Fixed issue #655 - shorthands override merging.
• Fixed issue #660 - !important token overriding.
• Fixed issue #662 - !important selector reducing.
• Fixed issue #667 - rebasing remote URLs.

3.4.1 / 2015-08-27

• Fixed issue #652 - order of restoring and removing tokens.

3.4.0 / 2015-08-27

• Adds an option for a fine-grained @import control.
• Adds unit compatibility switches to disable length optimizations.
• Adds inferring proxy settings from HTTP_PROXY environment variable.
• Adds support for Polymer / Web Components special selectors.
• Adds support for Polymer mixins.
• Adds testing source maps in batch mode.
• Unifies wrappers for simple & advanced optimizations.
• Fixed issue #596 - support for !ie IE<8 hack.
• Fixed issue #599 - support for inlined source maps.
• Fixed issue #607 - adds better rule reordering.
• Fixed issue #612 - adds HTTP proxy support.
• Fixed issue #618 - adds safer function validation.
• Fixed issue #625 - adds length unit optimizations.
• Fixed issue #632 - adds disabling remote imports.
• Fixed issue #635 - adds safer 0% optimizations.
• Fixed issue #644 - adds time unit optimizations.
• Fixed issue #645 - adds bottom to top media merging.
• Fixed issue #648 - adds property level at-rule support.

3.3.10 / 2015-08-27

• Adds better comments + keepBreaks handling.
• Adds better text normalizing in source maps mode.
• Fixes non-adjacent optimizations for source maps.
• Fixes removing unused items.
• Improves outline break up with source maps.
• Refixed issue #629 - source maps & background shorthands.

3.3.9 / 2015-08-09

• Fixed issue #640 - URI processing regression.

3.3.8 / 2015-08-06

• Fixed issue #629 - source maps & background shorthands.
• Fixed issue #630 - vendor prefixed flex optimizations.
• Fixed issue #633 - handling data URI with brackets.
• Fixed issue #634 - merging :placeholder selectors.

3.3.7 / 2015-07-29

• Fixed issue #616 - ordering in restructuring.

3.3.6 / 2015-07-14

• Fixed issue #620 - bold style in font shorthands.

3.3.5 / 2015-07-01

• Fixed issue #608 - custom URI protocols handling.

3.3.4 / 2015-06-24

• Fixed issue #610 - border:inherit restoring.
• Fixed issue #611 - edge case in quote stripping.

3.3.3 / 2015-06-16

• Fixed issue #603 - IE suffix hack defaults to on.

3.3.2 / 2015-06-14

• Fixed issue #595 - more relaxed block matching.
• Fixed issue #601 - percentage minifying inside flex.
• Fixed issue #602 - backslash IE hacks after a space.

3.3.1 / 2015-06-02

• Fixed issue #590 - edge case in @import processing.

3.3.0 / 2015-05-31

• Cleans up url rebase code getting rid of unnecessary state.
• Cleans up tokenizer code getting rid of unnecessary state.
• Moves source maps tracker into lib/source-maps/track.
• Moves tokenizer code into lib/tokenizer.
• Moves URL scanner into lib/urls/reduce (was named incorrectly before).
• Moves URL rebasing & rewriting into lib/urls.
• Fixed issue #375 - unit compatibility switches.
• Fixed issue #436 - refactors URI rewriting.
• Fixed issue #448 - rebasing no protocol URIs.
• Fixed issue #517 - turning off color optimizations.
• Fixed issue #542 - space after closing brace in IE.
• Fixed issue #562 - optimizing invalid color values.
• Fixed issue #563 - background:inherit restoring.
• Fixed issue #570 - rebasing "no-url()" imports.
• Fixed issue #574 - rewriting internal URLs.
• Fixed issue #575 - missing directory as a target.
• Fixed issue #577 - background-clip into shorthand.
• Fixed issue #579 - background-origin into shorthand.
• Fixed issue #580 - mixed @import processing.
• Fixed issue #582 - overriding with prefixed values.
• Fixed issue #583 - URL quoting for SVG data.
• Fixed issue #587 - too aggressive border reordering.

3.2.11 / 2015-05-31

• Fixed issue #563 - background:inherit restoring.
• Fixed issue #582 - overriding with prefixed values.
• Fixed issue #583 - URL quoting for SVG data.
• Fixed issue #587 - too aggressive border reordering.

3.2.10 / 2015-05-14

• Fixed issue #572 - empty elements removal.

3.2.9 / 2015-05-08

• Fixed issue #567 - merging colors as functions.

3.2.8 / 2015-05-04

• Fixed issue #561 - restructuring special selectors.

3.2.7 / 2015-05-03

• Fixed issue #551 - edge case in restructuring.
• Fixed issue #553 - another style of SVG fallback.
• Fixed issue #558 - units in same selector merging.

3.2.6 / 2015-04-28

• Fixed issue #550 - proper contentSources tracking.
• Fixed issue #556 - regression in IE backslash hacks.

3.2.5 / 2015-04-25

• Fixed issue #543 - better "comment in body" handling.
• Fixed issue #548 - regression in font minifying.
• Fixed issue #549 - special comments in source maps.

3.2.4 / 2015-04-24

• Fixed issue #544 - regression in same value merging.
• Fixed issue #546 - IE<11 calc() issue.

3.2.3 / 2015-04-22

• Fixed issue #541 - outline-style:auto in shorthand.

3.2.2 / 2015-04-21

• Fixed issue #537 - regression in simple optimizer.

3.2.1 / 2015-04-20

• Fixed issue #534 - wrong @font-face stringifying.

3.2.0 / 2015-04-19

• Bumps commander to 2.8.x.
• Fixes remote asset rebasing when passing data as a hash.
• Improves path resolution inside source maps.
• Makes root option implicitely default to process.cwd().
• Fixed issue #371 - background fallback with none.
• Fixed issue #376 - option to disable 0[unit] -> 0.
• Fixed issue #396 - better input source maps tracking.
• Fixed issue #397 - support for source map sources.
• Fixed issue #399 - support compacting with source maps.
• Fixed issue #429 - unifies data tokenization.
• Fixed issue #446 - list-style fuzzy matching.
• Fixed issue #468 - bumps source-map to 0.4.x.
• Fixed issue #480 - extracting uppercase property names.
• Fixed issue #487 - source map paths under Windows.
• Fixed issue #490 - vendor prefixed multivalue background.
• Fixed issue #500 - merging duplicate adjacent properties.
• Fixed issue #504 - keeping url() quotes.
• Fixed issue #507 - merging longhands into many shorthands.
• Fixed issue #508 - removing duplicate media queries.
• Fixed issue #521 - unit optimizations inside calc().
• Fixed issue #524 - timeouts in @import inlining.
• Fixed issue #526 - shorthand overriding into a function.
• Fixed issue #528 - better support for IE<9 hacks.
• Fixed issue #529 - wrong font weight minification.

3.1.9 / 2015-04-04

• Fixes issue #511 - ) advanced processing.

3.1.8 / 2015-03-17

• Fixes issue #498 - reordering and flexbox.
• Fixes issue #499 - too aggressive - removal.

3.1.7 / 2015-03-16

• Backports fix to #480 - reordering and uppercase properties.
• Fixes issue #496 - space after bracket removal.

3.1.6 / 2015-03-12

• Fixes issue #489 - AlphaImageLoader IE filter.

3.1.5 / 2015-03-06

• Fixes issue #483 - property order in restructuring.

3.1.4 / 2015-03-04

• Fixes issue #472 - broken function minification.
• Fixes issue #477 - @imports order in restructuring.
• Fixes issue #478 - ultimate fix to brace whitespace.

3.1.3 / 2015-03-03

• Fixes issue #464 - data URI with quoted braces.
• Fixes issue #475 - whitespace after closing brace.

3.1.2 / 2015-03-01

• Refixed issue #471 - correct order after restructuring.
• Fixes issue #466 - rebuilding background shorthand.
• Fixes issue #462 - escaped apostrophes in selectors.

3.1.1 / 2015-02-27

• Fixed issue #469 - extracting broken property.
• Fixed issue #470 - negative padding removal.
• Fixed issue #471 - correct order after restructuring.

3.1.0 / 2015-02-26

• Adds 0deg to 0 minification where possible.
• Adds better non-adjacent selector merging when body is the same.
• Adds official support for node.js 0.12.
• Adds official support for io.js 1.0.
• Adds restructuring optimizations to reorganize selectors, which vastly improves minification.
• Fixed issue #158 - adds body-based selectors reduction.
• Fixed issue #182 - removing space after closing brace.
• Fixed issue #204 - @media merging.
• Fixed issue #351 - remote @imports after content.
• Fixed issue #357 - non-standard but valid URLs.
• Fixed issue #416 - accepts hash as minify argument.
• Fixed issue #419 - multiple input source maps.
• Fixed issue #435 - background-clip in shorthand.
• Fixed issue #439 - background-origin in shorthand.
• Fixed issue #442 - space before adjacent nav.
• Fixed issue #445 - regression issue in url processor.
• Fixed issue #449 - warns of missing close braces.
• Fixed issue #463 - relative remote @import URLs.

3.0.10 / 2015-02-07

• Fixed issue #453 - double background-repeat.
• Fixed issue #455 - property extracting regression.

3.0.9 / 2015-02-04

• Fixed issue #452 - regression in advanced merging.

3.0.8 / 2015-01-31

• Fixed issue #447 - background-color in shorthands.
• Fixed issue #450 - name to hex color converting.

3.0.7 / 2015-01-22

• Fixed issue #441 - hex to name color converting.

3.0.6 / 2015-01-20

• Refixed issue #414 - source maps position fallback.

3.0.5 / 2015-01-18

• Fixed issue #414 - source maps position fallback.
• Fixed issue #433 - meging !important in shorthands.

3.0.4 / 2015-01-11

• Fixed issue #314 - spaces inside calc.

3.0.3 / 2015-01-07

• Just a version bump as npm incorrectly things 2.2.23 is the latest one.

3.0.2 / 2015-01-04

• Fixed issue #422 - handling calc as a unit.

3.0.1 / 2014-12-19

• Fixed issue #410 - advanced merging and comments.
• Fixed issue #411 - properties and important comments.

3.0.0 / 2014-12-18

• Adds more granular control over compatibility settings.
• Adds support for @counter-style at-rule.
• Adds --source-map/sourceMap switch for building input's source map.
• Adds --skip-shorthand-compacting/shorthandComacting option for disabling shorthand compacting.
• Allows target option to be a path to a folder instead of a file.
• Allows disabling rounding precision. By @superlukas.
• Breaks 2.x compatibility for using CleanCSS as a function.
• Changes minify method output to handle multiple outputs.
• Reworks minification to tokenize first then minify. See changes.
• Removes support for node.js 0.8.x.
• Renames noAdvanced option into advanced.
• Renames noAggressiveMerging option into aggressiveMerging.
• Renames noRebase option into rebase.
• Speeds up advanced processing by shortening optimize loop.
• Fixed issue #125 - source maps!
• Fixed issue #344 - merging background-size into shorthand.
• Fixed issue #352 - honors rebasing in imported stylesheets.
• Fixed issue #360 - adds 7 extra CSS colors.
• Fixed issue #363 - rem units overriding px.
• Fixed issue #373 - proper background shorthand merging.
• Fixed issue #395 - unescaped brackets in data URIs.
• Fixed issue #398 - restoring important comments.
• Fixed issue #400 - API to accept an array of filenames.
• Fixed issue #403 - tracking input files in source maps.
• Fixed issue #404 - no state sharing in API.
• Fixed issue #405 - disables default background-size merging.
• Refixed issue #304 - background-position merging.

2.2.22 / 2014-12-13

• Backports fix to issue #304 - background-position merging.

2.2.21 / 2014-12-10

• Backports fix to issue #373 - background shorthand merging.

2.2.20 / 2014-12-02

• Backports fix to issue #390 - pseudo-class merging.

2.2.19 / 2014-11-20

• Fixed issue #385 - edge cases in processing cut off data.

2.2.18 / 2014-11-17

• Fixed issue #383 - rounding fractions once again.

2.2.17 / 2014-11-09

• Fixed issue #380 - rounding fractions to a whole number.

2.2.16 / 2014-09-16

• Fixed issue #359 - handling escaped double backslash.
• Fixed issue #358 - property merging in compatibility mode.
• Fixed issue #356 - preserving *+html hack.
• Fixed issue #354 - !important overriding in shorthands.

2.2.15 / 2014-09-01

• Fixed issue #343 - too aggressive rgba/hsla minification.
• Fixed issue #345 - URL rebasing for document relative ones.
• Fixed issue #346 - overriding !important by !important.
• Fixed issue #350 - edge cases in @import processing.

2.2.14 / 2014-08-25

• Makes multival operations idempotent.
• Fixed issue #339 - skips invalid properties.
• Fixed issue #341 - ensure output is shorter than input.

2.2.13 / 2014-08-12

• Fixed issue #337 - handling component importance.

2.2.12 / 2014-08-02

• Fixed issue with tokenizer removing first selector after an unknown @ rule.
• Fixed issue #329 - font shorthands incorrectly processed.
• Fixed issue #332 - background shorthand with colors.
• Refixed issue #325 - invalid charset declarations.

2.2.11 / 2014-07-28

• Fixed issue #326 - background-size regression.

2.2.10 / 2014-07-27

• Improved performance of advanced mode validators.
• Fixed issue #307 - background-color in multiple backgrounds.
• Fixed issue #322 - adds background-size support.
• Fixed issue #323 - stripping variable references.
• Fixed issue #325 - removing invalid @charset declarations.

2.2.9 / 2014-07-23

• Adds background normalization according to W3C spec.
• Fixed issue #316 - incorrect background processing.

2.2.8 / 2014-07-14

• Fixed issue #313 - processing comment marks in URLs.
• Fixed issue #315 - rgba/hsla -> transparent in gradients.

2.2.7 / 2014-07-10

• Fixed issue #304 - merging multiple backgrounds.
• Fixed issue #312 - merging with mixed repeat.

2.2.6 / 2014-07-05

• Adds faster quote matching in QuoteScanner.
• Improves QuoteScanner to handle comments correctly.
• Fixed issue #308 - parsing comments in quoted URLs.
• Fixed issue #311 - leading/trailing decimal points.

2.2.5 / 2014-06-29

• Adds removing extra spaces around / in border-radius.
• Adds replacing same horizontal & vertical value in border-radius.
• Fixed issue #305 - allows width keywords in border-width.

2.2.4 / 2014-06-27

• Fixed issue #301 - proper border-radius processing.
• Fixed issue #303 - correctly preserves viewport units.

2.2.3 / 2014-06-24

• Fixed issue #302 - handling of outline-style: auto.

2.2.2 / 2014-06-18

• Fixed issue #297 - box-shadow zeros minification.

2.2.1 / 2014-06-14

• Fixes new property optimizer for 'none' values.
• Fixed issue #294 - space after rgba/hsla in IE<=11.

2.2.0 / 2014-06-11

• Adds a better algorithm for quotation marks' removal.
• Adds a better non-adjacent optimizer compatible with the upcoming new property optimizer.
• Adds minifying remote files directly from CLI.
• Adds --rounding-precision to control rounding precision.
• Moves quotation matching into a QuoteScanner class.
• Adds npm run browserify for creating embeddable version of clean-css.
• Fixed list-style-* advanced processing.
• Fixed issue #134 - merges properties into shorthand form.
• Fixed issue #164 - removes default values if not needed.
• Fixed issue #168 - adds better property merging algorithm.
• Fixed issue #173 - merges same properties if grouped.
• Fixed issue #184 - uses !important for optimization opportunities.
• Fixed issue #190 - uses shorthand to override another shorthand.
• Fixed issue #197 - adds borders merging by understandability.
• Fixed issue #210 - adds temporary workaround for aggressive merging.
• Fixed issue #246 - removes IE hacks when not in compatibility mode.
• Fixed issue #247 - removes deprecated selectorsMergeMode switch.
• Refixed issue #250 - based on new quotation marks removal.
• Fixed issue #257 - turns rgba/hsla to transparent if possible.
• Fixed issue #265 - adds support for multiple input files.
• Fixed issue #275 - handling transform properties.
• Fixed issue #276 - corrects unicode handling.
• Fixed issue #288 - adds smarter expression parsing.
• Fixed issue #293 - handles escaped @ symbols in class names and IDs.

2.1.8 / 2014-03-28

• Fixed issue #267 - incorrect non-adjacent selector merging.

2.1.7 / 2014-03-24

• Fixed issue #264 - @import statements inside comments.

2.1.6 / 2014-03-10

• Fixed issue #258 - wrong @import handling in EmptyRemoval.

2.1.5 / 2014-03-07

• Fixed issue #255 - incorrect processing of a trailing -0.

2.1.4 / 2014-03-01

• Fixed issue #250 - correctly handle JSON data in quotations.

2.1.3 / 2014-02-26

• Fixed issue #248 - incorrect merging for vendor selectors.

2.1.2 / 2014-02-25

• Fixed issue #245 - incorrect handling of backslash IE hack.

2.1.1 / 2014-02-18

• Adds faster selectors processing in advanced optimizer.
• Fixed issue #241 - incorrect handling of :not() selectors.

2.1.0 / 2014-02-13

• Adds an optional callback to minify method.
• Deprecates --selectors-merge-mode / selectorsMergeMode in favor to --compatibility / compatibility.
• Fixes debug mode stats for stylesheets using @import statements.
• Skips empty removal if advanced processing is enabled.
• Fixed issue #85 - resolving protocol @imports.
• Fixed issue #160 - re-runs optimizer until a clean pass.
• Fixed issue #161 - improves tokenizer performance.
• Fixed issue #163 - round pixels to 2nd decimal place.
• Fixed issue #165 - extra space after trailing parenthesis.
• Fixed issue #186 - strip unit from 0rem.
• Fixed issue #207 - bug in parsing protocol @imports.
• Fixed issue #213 - faster rgb to hex transforms.
• Fixed issue #215 - leading zeros in numerical values.
• Fixed issue #217 - whitespace inside attribute selectors and URLs.
• Fixed issue #218 - @import statements cleanup.
• Fixed issue #220 - selector between comments.
• Fixed issue #223 - two-pass adjacent selectors merging.
• Fixed issue #226 - don't minify border:none to border:0.
• Fixed issue #229 - improved processing of fraction numbers.
• Fixed issue #230 - better handling of zero values.
• Fixed issue #235 - IE7 compatibility mode.
• Fixed issue #236 - incorrect rebasing with nested imports.

2.0.8 / 2014-02-07

• Fixed issue #232 - edge case in non-adjacent selectors merging.

2.0.7 / 2014-01-16

• Fixed issue #208 - don't swallow @page and @viewport.

2.0.6 / 2014-01-04

• Fixed issue #198 - process comments and @imports correctly.
• Fixed issue #205 - freeze on broken @import declaration.

2.0.5 / 2014-01-03

• Fixed issue #199 - keep line breaks with no advanced optimizations.
• Fixed issue #203 - Buffer as a first argument to minify method.

2.0.4 / 2013-12-19

• Fixed issue #193 - HSL color space normalization.

2.0.3 / 2013-12-18

• Fixed issue #191 - leading numbers in font/animation names.
• Fixed issue #192 - many @imports inside a comment.

2.0.2 / 2013-11-18

• Fixed issue #177 - process broken content correctly.

2.0.1 / 2013-11-14

• Fixed issue #176 - hangs on undefined keyword.

2.0.0 / 2013-11-04

• Adds simplified and more advanced text escaping / restoring via EscapeStore class.
• Adds simplified and much faster empty elements removal.
• Adds missing @import processing to our benchmark (run via npm run bench).
• Adds CSS tokenizer which will make it possible to optimize content by reordering and/or merging selectors.
• Adds basic optimizer removing duplicate selectors from a list.
• Adds merging duplicate properties within a single selector's body.
• Adds merging adjacent selectors within a scope (single and multiple ones).
• Changes behavior of --keep-line-breaks/keepBreaks option to keep breaks after trailing braces only.
• Makes all multiple selectors ordered alphabetically (aids merging).
• Adds property overriding so more coarse properties override more granular ones.
• Adds reducing non-adjacent selectors.
• Adds --skip-advanced/noAdvanced switch to disable advanced optimizations.
• Adds reducing non-adjacent selectors when overridden by more complex selectors.
• Fixed issue #138 - makes CleanCSS interface OO.
• Fixed issue #139 - consistent error & warning handling.
• Fixed issue #145 - debug mode in library too.
• Fixed issue #157 - gets rid of removeEmpty option.
• Fixed issue #159 - escaped quotes inside content.
• Fixed issue #162 - strip quotes from Base64 encoded URLs.
• Fixed issue #166 - debug formatting in CLI
• Fixed issue #167 - background:transparent minification.

1.1.7 / 2013-10-28

• Fixed issue #156 - @imports inside comments.

1.1.6 / 2013-10-26

• Fixed issue #155 - broken irregular CSS content.

1.1.5 / 2013-10-24

• Fixed issue #153 - keepSpecialComments 0/1 as a string.

1.1.4 / 2013-10-23

• Fixed issue #152 - adds an option to disable rebasing.

1.1.3 / 2013-10-04

• Fixed issue #150 - minifying background:none.

1.1.2 / 2013-09-29

• Fixed issue #149 - shorthand font property.

1.1.1 / 2013-09-07

• Fixed issue #144 - skip URLs rebasing by default.

1.1.0 / 2013-09-06

• Renamed lib's debug option to benchmark when doing per-minification benchmarking.
• Added simplified comments processing & imports.
• Fixed issue #43 - --debug switch for minification stats.
• Fixed issue #65 - full color name / hex shortening.
• Fixed issue #84 - support for @import with media queries.
• Fixed issue #124 - raise error on broken imports.
• Fixed issue #126 - proper CSS expressions handling.
• Fixed issue #129 - rebasing imported URLs.
• Fixed issue #130 - better code modularity.
• Fixed issue #135 - require node.js 0.8+.

1.0.12 / 2013-07-19

• Fixed issue #121 - ability to skip @import processing.

1.0.11 / 2013-07-08

• Fixed issue #117 - line break escaping in comments.

1.0.10 / 2013-06-13

• Fixed issue #114 - comments in imported stylesheets.

1.0.9 / 2013-06-11

• Fixed issue #113 - @import in comments.

1.0.8 / 2013-06-10

• Fixed issue #112 - reducing box-shadow zeros.

1.0.7 / 2013-06-05

• Support for @import URLs starting with //. By @petetak.

1.0.6 / 2013-06-04

• Fixed issue #110 - data URIs in URLs.

1.0.5 / 2013-05-26

• Fixed issue #107 - data URIs in imported stylesheets.

1.0.4 / 2013-05-23

• Rewrite relative URLs in imported stylesheets. By @bluej100.

1.0.3 / 2013-05-20

• Support alternative @import syntax with file name not wrapped inside url() statement. By @bluej100.

1.0.2 / 2013-04-29

• Fixed issue #97 - --remove-empty & FontAwesome.

1.0.1 / 2013-04-08

• Do not pick up bench and test while building npm package. By @sindresorhus.

1.0.0 / 2013-03-30

• Fixed issue #2 - resolving @import rules.
• Fixed issue #44 - examples in --help.
• Fixed issue #46 - preserving special characters in URLs and attributes.
• Fixed issue #80 - quotation in multi line strings.
• Fixed issue #83 - HSL to hex color conversions.
• Fixed issue #86 - broken @charset replacing.
• Fixed issue #88 - removes space in ! important.
• Fixed issue #92 - uppercase hex to short versions.

0.10.2 / 2013-03-19

• Fixed issue #79 - node.js 0.10.x compatibility.

0.10.1 / 2013-02-14

• Fixed issue #66 - line breaks without extra spaces should be handled correctly.

0.10.0 / 2013-02-09

• Switched from optimist to commander for CLI processing.
• Changed long options from --removeempty to --remove-empty and from --keeplinebreaks to --keep-line-breaks.
• Fixed performance issue with replacing multiple @charset declarations and issue with line break after @charset when using keepLineBreaks option. By @rrjaime.
• Removed Makefile in favor to npm run commands (e.g. make check -> npm run check).
• Fixed issue #47 - commandline issues on Windows.
• Fixed issue #49 - remove empty selectors from media query.
• Fixed issue #52 - strip fraction zeros if not needed.
• Fixed issue #58 - remove colon where possible.
• Fixed issue #59 - content property handling.

0.9.1 / 2012-12-19

• Fixed issue #37 - converting white and other colors in class names (reported by @malgorithms).

0.9.0 / 2012-12-15

• Added stripping quotation from font names (if possible).
• Added stripping quotation from @keyframes declaration, animation and animation-name property.
• Added stripping quotations from attributes' value (e.g. [data-target='x']).
• Added better hex->name and name->hex color shortening.
• Added font: normal and font: bold shortening the same way as font-weight is.
• Refactored shorthand selectors and added border-radius, border-style and border-color shortening.
• Added margin, padding and border-width shortening.
• Added removing line break after commas.
• Fixed removing whitespace inside media query definition.
• Added removing line breaks after a comma, so all declarations are one-liners now.
• Speed optimizations (~10% despite many new features).
• Added JSHint validation rules via make check.

0.8.3 / 2012-11-29

• Fixed HSL/HSLA colors processing.

0.8.2 / 2012-10-31

• Fixed shortening hex colors and their relation to hashes in URLs.
• Cleanup by @XhmikosR.

0.8.1 / 2012-10-28

• Added better zeros processing for rect(...) syntax (clip property).

0.8.0 / 2012-10-21

• Added removing URLs quotation if possible.
• Rewrote breaks processing.
• Added keepBreaks/-b option to keep line breaks in the minimized file.
• Reformatted lib/clean.js so it's easier to follow the rules.
• Minimized test data is now minimized with line breaks so it's easier to compare the changes line by line.

0.7.0 / 2012-10-14

• Added stripping special comments to CLI (--s0 and --s1 options).
• Added stripping special comments to programmatic interface (keepSpecialComments option).

0.6.0 / 2012-08-05

• Full Windows support with tests (./test.bat).

0.5.0 / 2012-08-02

• Made path to vows local.
• Explicit node.js 0.6 requirement.

0.4.2 / 2012-06-28

• Updated binary -v option (version).
• Updated binary to output help when no options given (but not in piped mode).
• Added binary tests.

0.4.1 / 2012-06-10

• Fixed stateless mode where calling CleanCSS#process directly was giving errors (reported by @facelessuser).

0.4.0 / 2012-06-04

• Speed improvements up to 4x thanks to the rewrite of comments and CSS' content processing.
• Stripping empty CSS tags is now optional (see bin/cleancss for details).
• Improved debugging mode (see test/bench.js)
• Added make bench for a one-pass benchmark.

0.3.3 / 2012-05-27

• Fixed tests, package.json for development, and regex for removing empty declarations (thanks to @vvo).

0.3.2 / 2012-01-17

• Fixed output method under node.js 0.6 which incorrectly tried to close process.stdout.

0.3.1 / 2011-12-16

• Fixed cleaning up 0 0 0 0 expressions.

0.3.0 / 2011-11-29

• Clean-css requires node.js 0.4.0+ to run.
• Removed node.js's 0.2.x 'sys' package dependency (thanks to @jmalonzo for a patch).

0.2.6 / 2011-11-27

• Fixed expanding + signs in calc() when mixed up with adjacent + selector.

0.2.5 / 2011-11-27

• Fixed issue with cleaning up spaces inside calc/-moz-calc declarations (thanks to @cvan for reporting it).
• Fixed converting #f00 to red in borders and gradients.

0.2.4 / 2011-05-25

• Fixed problem with expanding none to 0 in partial/full background declarations.
• Fixed including clean-css library from binary (global to local).

0.2.3 / 2011-04-18

• Fixed problem with optimizing IE filters.

0.2.2 / 2011-04-17

• Fixed problem with space before color in border property.

0.2.1 / 2011-03-19

• Added stripping space before !important keyword.
• Updated repository location and author information in package.json.

0.2.0 / 2011-03-02

• Added options parsing via optimist.
• Changed code inclusion (thus the version bump).

0.1.0 / 2011-02-27

• First version of clean-css library.
• Implemented all basic CSS transformations.