Trello board style experiments. Put this in Stylebot in Chrome. Didn't test in other browsers but it probably works in Safari, too. :)

style.css

#board {
    background: none;
    border-radius: 0;
    box-shadow: none;
    margin-left: 0;
    margin-right: 250px;
    padding: 0;
}

#board-header {
    margin: 0;
    padding: 16px 10px 18px 20px;
}

#board-header .board-name {
    font-size: 24px;
    margin-right: 12px;
    padding-left: 3px;
    text-shadow: 0px 1px 4px rgba(0,0,0,.7);
}

#board-header .board-name:hover, #board-header .org-name:hover, #board-header .board-header-btn:hover {
    background: rgba(0,0,0,.4);
}

#board-header .icon-board {
    color: #fff;
}

#board-header .icon-sm {
    color: #ffffff;
}

#board-header .quiet {
    opacity: .5;
}

#board-header .quiet:hover {
    opacity: 1;
}

#board-header .text, #board-header .org-name {
    color: #ffffff;
}

#board-header a {
    text-decoration: none;
}

#content {
    background-color: #1a272d;
}

#header {
    background: linear-gradient(to bottom, #1a272d 0%, #2b373c 40%, #2b373c 90%, #1a272d 100%) ;
    /* background: linear-gradient(to bottom, #e4e9ec 0%, #e0e5e8 50%, #c5ccd0 100%);
    box-shadow: 0px 1px 2px rgba(0,0,0,.5);
    box-shadow: 0px 1px 3px rgba(0,0,0,.25);
    */
    z-index: 10;
}

#header * {
    -webkit-transition: .2s opacity;
}

#header .header-help .header-btn-text {
    display: none;
}

#header .header-logo {
    opacity: 1;
}

#header-search .header-btn {
    display: none;
}

#header-search input[type="text"] {
    background: #ffffff;
    border-radius: 5px;
    height: 23px;
    margin: 3px 0px;
    min-height: 0px;
    opacity: .2;
}

#header-search input[type="text"]:focus {
    opacity: 1;
}

#header-search input[type="text"]:hover {
    opacity: .9;
}

.activity-gradient-t, .activity-gradient-b {
    display: none;
}

.badges {
    padding: 2px 10px 5px 10px;
}

.board-side-btn {
    z-index: 5;
}

.board-side-btn .arrow {
    border-left-color: rgba(0,0,0,.3);
    border-right-color: rgba(0,0,0,.3);
}

.board-side-btn.left-side {
    -webkit-border-bottom-right-radius: 100px;
    -webkit-border-top-right-radius: 100px;
}

.board-side-btn.right-side {
    -webkit-border-bottom-left-radius: 100px;
    -webkit-border-top-left-radius: 100px;
}

.board-side-btn:hover {
    background: rgba(0,0,0,.2);
}

.board-widget {
    padding: 20px;
}

.board-widget-activity {
    background: #ffffff;
    padding-right: 10px;
}

.board-widget-members .member {
    margin: 0 5px 5px 0;
}

.board-widget-title h3 {
    color: #a9a9a9;
    font-size: 12px;
    letter-spacing: .1em;
    text-transform: uppercase;
}

.board-widgets {
    background-color: #edeff0;
    border-top-right-radius: 10px;
    box-shadow: -2px 1px 7px rgba(0,0,0,.4);
    padding: 0;
    position: absolute;
    right: 0;
    top: 0;
    width: 250px;
    z-index: 9;
}

.board-widgets .button-link {
    background: none;
    border: none;
    padding: 2px 0;
}

.board-widgets .button-link .icon-sm {
    color: rgb(68, 68, 68);
}

.board-widgets .button-link:hover, .board-widgets .button-link:hover .icon-sm {
    color: #226489;
}

.board-wrapper {
    background: #216f95;
    border-top-left-radius: 10px;
    border-top-right-radius: 10px;
}

.card-detail-title {
    color: rgb(57, 57, 57);
}

.card-label.blue-label {
    background-color: #2980B9;
}

.card-label.green-label {
    background-color: #27AE60;
}

.card-label.orange-label {
    background-color: #E67E22;
}

.card-label.purple-label {
    background-color: #8E44AD;
}

.card-label.red-label {
    background-color: #C0392B;
}

.card-label.yellow-label {
    background-color: #F1C40F;
}

.card-labels {
    margin: 0;
    width: 100%;
}

.extra-large-window .board-wrapper.disabled-all-widgets #board, .large-window .board-wrapper.disabled-all-widgets #board, .medium-window .board-wrapper.disabled-all-widgets #board {
    margin-right: 0px
;
}

.header-btn {
    -webkit-box-shadow: none;
    background: none;
    box-shadow: none;
    opacity: .4;
}

.header-btn:hover {
    opacity: 1;
}

.list {
    background: #e4e8ea;
    border: 0;
    box-shadow: 0px 2px 10px rgba(0,0,0,.5);
    margin: 0 5px;
}

.list-area-wrapper {
    padding: 0px 15px 24px 15px;
}

.list-card {
    border: 1px solid #BDC3C7;
    margin: 0px 2px 5px 2px;
    padding: 0px;
}

.list-card .card-label {
    height: 5px;
    margin-bottom: 0;
    width: 100%;
}

.list-card-cover img {
    width: 100%;
}

.list-card-members {
    margin: 0 2px 1px 5px;
}

.list-card-members .member {
    border: none;
    height: 25px;
    margin: 0 4px 4px 0;
    width: 25px;
}

.list-card-title {
    color: #515151;
    font-size: 14px;
    line-height: 1.4em;
    margin: 8px 10px 6px 10px;
}

.list-card:hover {
    border: 1px solid #2980B9;
}

.list-gradient-bottom {
    background: linear-gradient(to bottom, rgba(228, 232, 234, 0) 0%, #e4e8ea 100%);
}

.list-gradient-top {
    background: linear-gradient(to bottom, #e4e8ea 0%, rgba(228, 232, 234, 0) 100%);
}

.list-title {
    padding: 5px 0px 4px 0px;
}

.list-title h2 {
    font-size: 1.24em;
}

.member {
    border: none;
    border-radius: 3px;
}

.member .status, .member .member-type {
    border: 1px solid #fff;
    border-bottom: none;
    border-radius: 5px;
    border-right: none;
    bottom: 1px;
    height: 5px;
    right: 1px;
    width: 5px;
}

.member img {
    height: 100%;
    width: 100%;
}

.window .window-main-col {
    background: none;
}

.window-main-col {
    -webkit-border-bottom-left-radius: 5px;
    -webkit-border-top-left-radius: 5px;
    background: #fff;
    padding: 12px;
}

.window-overlay {
    z-index: 10;
}

.window-sidebar {
    -webkit-border-bottom-right-radius: 5px;
    -webkit-border-top-right-radius: 5px;
    background: #f0f0f0;
    padding: 12px;
}

.window-title {
    width: 100%;
}

.window-title, .window-title-extra {
    color: #ffffff;
}

.window-title-text {
    color: black;
}

::-webkit-scrollbar {
    height: 14px;
    width: 6px;
}

::-webkit-scrollbar-thumb {
    background: rgba(0,0,0,.2);
}

::-webkit-scrollbar-track-piece:horizontal {
    background: none;
}

::webkit-scrollbar-track-piece:vertical {
    background: rgba(0,0,0,.1);
}

body {
    background: #216f95;
}

/* #header .header-logo .logo {
    background-image: url(http://tinabeans.com/fc/Trellogo_color.png);
    background-size: 100%;
    margin-top: 2px;
} */

html, body, #surface, #content, .board-wrapper, #board {
    height: 100%;
}

textarea.js-card-title {
    margin: 0;
    padding: 10px;
}