🐛 Fixed incorrect/missing colours for various elements

closes https://github.com/TryGhost/Casper/issues/548
- the recent postcss upgrade resulted in real CSS variables being output with a fallback mechanism, unfortunately this broke a number of colors throughout the theme
- disabled the fallback mechanism to revert back to the previous behaviour

assets/built/global.css

@@ -1,2 +1,2 @@
-:root{--blue:#3eb0ef;--green:#a4d037;--purple:#ad26b4;--yellow:#fecd35;--red:#f05230;--darkgrey:#15171a;--midgrey:#738a94;--lightgrey:#c5d2d9;--whitegrey:#e5eff5;--pink:#fa3a57;--brown:#a3821a}a,abbr,acronym,address,applet,article,aside,audio,big,blockquote,body,canvas,caption,cite,code,dd,del,details,dfn,div,dl,dt,em,embed,fieldset,figcaption,figure,footer,form,h1,h2,h3,h4,h5,h6,header,hgroup,html,iframe,img,ins,kbd,label,legend,li,mark,menu,nav,object,ol,output,p,pre,q,ruby,s,samp,section,small,span,strike,strong,sub,summary,sup,table,tbody,td,tfoot,th,thead,time,tr,tt,ul,var,video{margin:0;padding:0;border:0;font:inherit;font-size:100%;vertical-align:baseline}body{line-height:1}ol,ul{list-style:none}blockquote,q{quotes:none}blockquote:after,blockquote:before,q:after,q:before{content:"";content:none}img{max-width:100%}html{-webkit-box-sizing:border-box;box-sizing:border-box;font-family:sans-serif;-ms-text-size-adjust:100%;-webkit-text-size-adjust:100%}*,:after,:before{-webkit-box-sizing:inherit;box-sizing:inherit}a{background-color:transparent}a:active,a:hover{outline:0}b,strong{font-weight:700}dfn,em,i{font-style:italic}h1{margin:.67em 0;font-size:2em}small{font-size:80%}sub,sup{position:relative;font-size:75%;line-height:0;vertical-align:baseline}sup{top:-.5em}sub{bottom:-.25em}img{border:0}svg:not(:root){overflow:hidden}mark{background-color:#fdffb6}code,kbd,pre,samp{font-family:monospace,monospace;font-size:1em}button,input,optgroup,select,textarea{margin:0;color:inherit;font:inherit}button{overflow:visible;border:none}button,select{text-transform:none}button,html input[type=button],input[type=reset],input[type=submit]{cursor:pointer;-webkit-appearance:button}button[disabled],html input[disabled]{cursor:default}button::-moz-focus-inner,input::-moz-focus-inner{padding:0;border:0}input{line-height:normal}input:focus{outline:none}input[type=checkbox],input[type=radio]{-webkit-box-sizing:border-box;box-sizing:border-box;padding:0}input[type=number]::-webkit-inner-spin-button,input[type=number]::-webkit-outer-spin-button{height:auto}input[type=search]{-webkit-box-sizing:content-box;box-sizing:content-box;-webkit-appearance:textfield}input[type=search]::-webkit-search-cancel-button,input[type=search]::-webkit-search-decoration{-webkit-appearance:none}legend{padding:0;border:0}textarea{overflow:auto}table{border-spacing:0;border-collapse:collapse}td,th{padding:0}html{overflow-y:scroll;font-size:62.5%;-webkit-tap-highlight-color:rgba(0,0,0,0)}body,html{overflow-x:hidden}body{color:#3c484e;color:color(var(--midgrey) l(-25%));font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Open Sans,Helvetica Neue,sans-serif;font-size:1.5rem;line-height:1.6em;font-weight:400;font-style:normal;letter-spacing:0;text-rendering:optimizeLegibility;background:#fff;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;-moz-font-feature-settings:"liga" on}::selection{text-shadow:none;background:#cbeafb;background:color(var(--blue) lightness(30%))}hr{position:relative;display:block;width:100%;margin:2.5em 0 3.5em;padding:0;height:1px;border:0;border-top:1px solid #e3e9ed;border-top:1px solid color(var(--lightgrey) l(10%))}audio,canvas,iframe,img,svg,video{vertical-align:middle}fieldset{margin:0;padding:0;border:0}textarea{resize:vertical}blockquote,dl,ol,p,ul{margin:0 0 1.5em}ol,ul{padding-left:1.3em;padding-right:1.5em}ol ol,ol ul,ul ol,ul ul{margin:.5em 0 1em}ul{list-style:disc}ol{list-style:decimal}ol,ul{max-width:100%}li{margin:.5em 0;padding-left:.3em;line-height:1.6em}dt{float:left;margin:0 20px 0 0;width:120px;color:#15171a;color:var(--darkgrey);font-weight:500;text-align:right}dd{margin:0 0 5px;text-align:left}blockquote{margin:1.5em 0;padding:0 1.6em;border-left:.5em solid #e5eff5;border-left:.5em solid var(--whitegrey)}blockquote p{margin:.8em 0;font-size:1.2em;font-weight:300}blockquote small{display:inline-block;margin:.8em 0 .8em 1.5em;font-size:.9em;opacity:.8}blockquote small:before{content:"\2014 \00A0"}blockquote cite{font-weight:700}blockquote cite a{font-weight:400}a{color:#26a8ed;color:color(var(--blue) l(-5%));text-decoration:none}a:hover{text-decoration:underline}h1,h2,h3,h4,h5,h6{margin-top:0;line-height:1.15;font-weight:700;text-rendering:optimizeLegibility}h1{margin:0 0 .5em;font-size:5rem;font-weight:700}@media (max-width:500px){h1{font-size:2.2rem}}h2{margin:1.5em 0 .5em;font-size:2rem}@media (max-width:500px){h2{font-size:1.8rem}}h3{margin:1.5em 0 .5em;font-size:1.8rem;font-weight:500}@media (max-width:500px){h3{font-size:1.7rem}}h4{margin:1.5em 0 .5em;font-size:1.6rem;font-weight:500}h5,h6{margin:1.5em 0 .5em;font-size:1.4rem;font-weight:500}
+a,abbr,acronym,address,applet,article,aside,audio,big,blockquote,body,canvas,caption,cite,code,dd,del,details,dfn,div,dl,dt,em,embed,fieldset,figcaption,figure,footer,form,h1,h2,h3,h4,h5,h6,header,hgroup,html,iframe,img,ins,kbd,label,legend,li,mark,menu,nav,object,ol,output,p,pre,q,ruby,s,samp,section,small,span,strike,strong,sub,summary,sup,table,tbody,td,tfoot,th,thead,time,tr,tt,ul,var,video{margin:0;padding:0;border:0;font:inherit;font-size:100%;vertical-align:baseline}body{line-height:1}ol,ul{list-style:none}blockquote,q{quotes:none}blockquote:after,blockquote:before,q:after,q:before{content:"";content:none}img{max-width:100%}html{-webkit-box-sizing:border-box;box-sizing:border-box;font-family:sans-serif;-ms-text-size-adjust:100%;-webkit-text-size-adjust:100%}*,:after,:before{-webkit-box-sizing:inherit;box-sizing:inherit}a{background-color:transparent}a:active,a:hover{outline:0}b,strong{font-weight:700}dfn,em,i{font-style:italic}h1{margin:.67em 0;font-size:2em}small{font-size:80%}sub,sup{position:relative;font-size:75%;line-height:0;vertical-align:baseline}sup{top:-.5em}sub{bottom:-.25em}img{border:0}svg:not(:root){overflow:hidden}mark{background-color:#fdffb6}code,kbd,pre,samp{font-family:monospace,monospace;font-size:1em}button,input,optgroup,select,textarea{margin:0;color:inherit;font:inherit}button{overflow:visible;border:none}button,select{text-transform:none}button,html input[type=button],input[type=reset],input[type=submit]{cursor:pointer;-webkit-appearance:button}button[disabled],html input[disabled]{cursor:default}button::-moz-focus-inner,input::-moz-focus-inner{padding:0;border:0}input{line-height:normal}input:focus{outline:none}input[type=checkbox],input[type=radio]{-webkit-box-sizing:border-box;box-sizing:border-box;padding:0}input[type=number]::-webkit-inner-spin-button,input[type=number]::-webkit-outer-spin-button{height:auto}input[type=search]{-webkit-box-sizing:content-box;box-sizing:content-box;-webkit-appearance:textfield}input[type=search]::-webkit-search-cancel-button,input[type=search]::-webkit-search-decoration{-webkit-appearance:none}legend{padding:0;border:0}textarea{overflow:auto}table{border-spacing:0;border-collapse:collapse}td,th{padding:0}html{overflow-y:scroll;font-size:62.5%;-webkit-tap-highlight-color:rgba(0,0,0,0)}body,html{overflow-x:hidden}body{color:#3c484e;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Open Sans,Helvetica Neue,sans-serif;font-size:1.5rem;line-height:1.6em;font-weight:400;font-style:normal;letter-spacing:0;text-rendering:optimizeLegibility;background:#fff;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;-moz-font-feature-settings:"liga" on}::selection{text-shadow:none;background:#cbeafb}hr{position:relative;display:block;width:100%;margin:2.5em 0 3.5em;padding:0;height:1px;border:0;border-top:1px solid #e3e9ed}audio,canvas,iframe,img,svg,video{vertical-align:middle}fieldset{margin:0;padding:0;border:0}textarea{resize:vertical}blockquote,dl,ol,p,ul{margin:0 0 1.5em}ol,ul{padding-left:1.3em;padding-right:1.5em}ol ol,ol ul,ul ol,ul ul{margin:.5em 0 1em}ul{list-style:disc}ol{list-style:decimal}ol,ul{max-width:100%}li{margin:.5em 0;padding-left:.3em;line-height:1.6em}dt{float:left;margin:0 20px 0 0;width:120px;color:#15171a;font-weight:500;text-align:right}dd{margin:0 0 5px;text-align:left}blockquote{margin:1.5em 0;padding:0 1.6em;border-left:.5em solid #e5eff5}blockquote p{margin:.8em 0;font-size:1.2em;font-weight:300}blockquote small{display:inline-block;margin:.8em 0 .8em 1.5em;font-size:.9em;opacity:.8}blockquote small:before{content:"\2014 \00A0"}blockquote cite{font-weight:700}blockquote cite a{font-weight:400}a{color:#26a8ed;text-decoration:none}a:hover{text-decoration:underline}h1,h2,h3,h4,h5,h6{margin-top:0;line-height:1.15;font-weight:700;text-rendering:optimizeLegibility}h1{margin:0 0 .5em;font-size:5rem;font-weight:700}@media (max-width:500px){h1{font-size:2.2rem}}h2{margin:1.5em 0 .5em;font-size:2rem}@media (max-width:500px){h2{font-size:1.8rem}}h3{margin:1.5em 0 .5em;font-size:1.8rem;font-weight:500}@media (max-width:500px){h3{font-size:1.7rem}}h4{margin:1.5em 0 .5em;font-size:1.6rem;font-weight:500}h5,h6{margin:1.5em 0 .5em;font-size:1.4rem;font-weight:500}
 /*# sourceMappingURL=global.css.map */

gulpfile.js

@@ -32,7 +32,7 @@ const handleError = (done) => {
 function css(done) {
     var processors = [
         easyimport,
-        customProperties,
+        customProperties({preserve: false}),
         colorFunction(),
         autoprefixer({browsers: ['last 2 versions']}),
         cssnano()