This includes all the minified CSS included in a base install of the Center theme. It's helpful as a baseline for use in style guides.

drupal-center.css

#comments{margin-top:15px;}.indented{margin-left:25px;}.comment-unpublished{background-color:#fff4f4;}.comment-preview{background-color:#ffffea;}
.container-inline-date{clear:both;}.container-inline-date .form-item{float:none;margin:0;padding:0;}.container-inline-date > .form-item{display:inline-block;margin-right:0.5em;margin-bottom:10px;vertical-align:top;}.container-inline-date .form-item .form-item{float:left;}.container-inline-date .form-item,.container-inline-date .form-item input{width:auto;}.container-inline-date .description{clear:both;}.container-inline-date .form-item input,.container-inline-date .form-item select,.container-inline-date .form-item option{margin-right:5px;}.container-inline-date .date-spacer{margin-left:-5px;}.views-right-60 .container-inline-date div{margin:0;padding:0;}.container-inline-date .date-timezone .form-item{clear:both;float:none;width:auto;}.container-inline-date .date-padding{padding:10px;float:left;}.views-exposed-form .container-inline-date .date-padding{padding:0;}#calendar_div,#calendar_div td,#calendar_div th{margin:0;padding:0;}#calendar_div,.calendar_control,.calendar_links,.calendar_header,.calendar{border-collapse:separate;margin:0;width:185px;}.calendar td{padding:0;}span.date-display-single{}span.date-display-start{}span.date-display-end{}.date-prefix-inline{display:inline-block;}.date-clear{clear:both;display:block;float:none;}.date-no-float{clear:both;float:none;width:98%;}.date-float{clear:none;float:left;width:auto;}.date-float .form-type-checkbox{padding-right:1em;}.form-type-date-select .form-type-select[class$=hour]{margin-left:.75em;}.date-container .date-format-delete{float:left;margin-top:1.8em;margin-left:1.5em;}.date-container .date-format-name{float:left;}.date-container .date-format-type{float:left;padding-left:10px;}.date-container .select-container{clear:left;float:left;}div.date-calendar-day{background:#F3F3F3;border-top:1px solid #EEE;border-left:1px solid #EEE;border-right:1px solid #BBB;border-bottom:1px solid #BBB;color:#999;float:left;line-height:1;margin:6px 10px 0 0;text-align:center;width:40px;}div.date-calendar-day span{display:block;text-align:center;}div.date-calendar-day span.month{background-color:#B5BEBE;color:white;font-size:.9em;padding:2px;text-transform:uppercase;}div.date-calendar-day span.day{font-size:2em;font-weight:bold;}div.date-calendar-day span.year{font-size:.9em;padding:2px;}.form-item.form-item-instance-widget-settings-input-format-custom,.form-item.form-item-field-settings-enddate-required{margin-left:1.3em;}#edit-field-settings-granularity .form-type-checkbox{margin-right:.6em;}.date-year-range-select{margin-right:1em;}
#ui-datepicker-div{font-size:100%;font-family:Verdana,sans-serif;background:#eee;border-right:2px #666 solid;border-bottom:2px #666 solid;z-index:9999;}.ui-datepicker{width:17em;padding:.2em .2em 0;}.ui-datepicker .ui-datepicker-header{position:relative;padding:.2em 0;}.ui-datepicker .ui-datepicker-prev,.ui-datepicker .ui-datepicker-next{position:absolute;top:2px;width:1.8em;height:1.8em;}.ui-datepicker .ui-datepicker-prev-hover,.ui-datepicker .ui-datepicker-next-hover{top:1px;}.ui-datepicker .ui-datepicker-prev{left:2px;}.ui-datepicker .ui-datepicker-next{right:2px;}.ui-datepicker .ui-datepicker-prev-hover{left:1px;}.ui-datepicker .ui-datepicker-next-hover{right:1px;}.ui-datepicker .ui-datepicker-prev span,.ui-datepicker .ui-datepicker-next span{display:block;position:absolute;left:50%;margin-left:-8px;top:50%;margin-top:-8px;}.ui-datepicker .ui-datepicker-title{margin:0 2.3em;line-height:1.8em;text-align:center;}.ui-datepicker .ui-datepicker-title select{float:left;font-size:1em;margin:1px 0;}.ui-datepicker select.ui-datepicker-month-year{width:100%;}.ui-datepicker select.ui-datepicker-month,.ui-datepicker select.ui-datepicker-year{width:49%;}.ui-datepicker .ui-datepicker-title select.ui-datepicker-year{float:right;}.ui-datepicker table{width:100%;font-size:.9em;border-collapse:collapse;margin:0 0 .4em;}.ui-datepicker th{padding:.7em .3em;text-align:center;font-weight:bold;border:0;}.ui-datepicker td{border:0;padding:1px;}.ui-datepicker td span,.ui-datepicker td a{display:block;padding:.2em;text-align:right;text-decoration:none;}.ui-datepicker .ui-datepicker-buttonpane{background-image:none;margin:.7em 0 0 0;padding:0 .2em;border-left:0;border-right:0;border-bottom:0;}.ui-datepicker .ui-datepicker-buttonpane button{float:right;margin:.5em .2em .4em;cursor:pointer;padding:.2em .6em .3em .6em;width:auto;overflow:visible;}.ui-datepicker .ui-datepicker-buttonpane button.ui-datepicker-current{float:left;}.ui-datepicker.ui-datepicker-multi{width:auto;}.ui-datepicker-multi .ui-datepicker-group{float:left;}.ui-datepicker-multi .ui-datepicker-group table{width:95%;margin:0 auto .4em;}.ui-datepicker-multi-2 .ui-datepicker-group{width:50%;}.ui-datepicker-multi-3 .ui-datepicker-group{width:33.3%;}.ui-datepicker-multi-4 .ui-datepicker-group{width:25%;}.ui-datepicker-multi .ui-datepicker-group-last .ui-datepicker-header{border-left-width:0;}.ui-datepicker-multi .ui-datepicker-group-middle .ui-datepicker-header{border-left-width:0;}.ui-datepicker-multi .ui-datepicker-buttonpane{clear:left;}.ui-datepicker-row-break{clear:both;width:100%;}.ui-datepicker-rtl{direction:rtl;}.ui-datepicker-rtl .ui-datepicker-prev{right:2px;left:auto;}.ui-datepicker-rtl .ui-datepicker-next{left:2px;right:auto;}.ui-datepicker-rtl .ui-datepicker-prev:hover{right:1px;left:auto;}.ui-datepicker-rtl .ui-datepicker-next:hover{left:1px;right:auto;}.ui-datepicker-rtl .ui-datepicker-buttonpane{clear:right;}.ui-datepicker-rtl .ui-datepicker-buttonpane button{float:left;}.ui-datepicker-rtl .ui-datepicker-buttonpane button.ui-datepicker-current{float:right;}.ui-datepicker-rtl .ui-datepicker-group{float:right;}.ui-datepicker-rtl .ui-datepicker-group-last .ui-datepicker-header{border-right-width:0;border-left-width:1px;}.ui-datepicker-rtl .ui-datepicker-group-middle .ui-datepicker-header{border-right-width:0;border-left-width:1px;}
.date-repeat-input{float:left;margin-right:5px;width:auto;}.date-repeat-input select{min-width:7em;}.date-repeat fieldset{clear:both;float:none;}.date-repeat-radios{margin-bottom:1em;}.date-repeat-radios input[type=radio]{float:left;margin:0.75em 0.75em 0 0;}.date-repeat-radios .form-wrapper{float:left;}.date-repeat-radios .form-type-checkboxes .form-type-checkbox{width:15%;float:left;margin:0;}.date-repeat-radios .date-repeat-radios-item{margin-bottom:1em;}.weekly .form-type-checkboxes .form-type-checkbox{float:left;margin-right:10px;}.date-repeat-input.byday-count label,.date-repeat-input.byday-count select,.date-clear.bymonthday label,.date-clear.bymonthday select{display:inline;}.date-repeat-input.byday-day label,.date-clear.bymonthday .field-suffix{font-weight:bold;}.range-of-repeat .form-radios > div{margin-top:0.5em;}.range-of-repeat .count input[type=text]{margin:0 0.5em;}.range-of-repeat .until .form-wrapper{margin:0 0.5em;display:inline-block;vertical-align:middle;}.range-of-repeat .until .form-radio,.range-of-repeat .until .date-prefix-inline{margin:0 0 1.4em 0;vertical-align:middle;}.range-of-repeat .until.widget-date_popup.label-above .form-radio,.range-of-repeat .until.widget-date_popup.label-above .date-prefix-inline{margin:0;vertical-align:middle;}.range-of-repeat .until.widget-date_select.label-within .form-radio,.range-of-repeat .until.widget-date_select.label-within .date-prefix-inline{margin:0;vertical-align:middle;}.range-of-repeat .until.widget-date_select.label-above .form-radio,.range-of-repeat .until.widget-date_select.label-above .date-prefix-inline{margin:1.4em 0 0 0;vertical-align:middle;}.range-of-repeat .until .form-type-date-text .date-padding{padding:0;}.range-of-repeat .until.widget-date_select.label-within .date-padding{padding:0;}.range-of-repeat .until.widget-date_select.label-above .date-padding{padding:0;}.range-of-repeat .until .form-type-date-select,.range-of-repeat .until .form-type-date-popup,.range-of-repeat .until .form-type-date-text{border:none;margin:0;}