    /**
     * @class Ext.panel.Panel
     */

    // TODO: setting this probably doesn't work well, since border-radius is typically
    // reserved for framed-panels - should we remove this?
    $panel-border-radius: null !default;

    /**
     * @var {number}
     * The default border-width of Panels
     */
    $panel-border-width: 1px !default;

    /**
     * @var {color}
     * The base color of Panels
     */
    $panel-base-color: $base-color !default;

    /**
     * @var {color}
     * The default border-color of Panels
     */
    $panel-border-color: $panel-base-color !default;

    /**
     * @var {$border-width-threshold}
     * The maximum width a Panel's border can be before resizer handles are embedded into the borders using negative absolute positions.
     *
     * This defaults to 2, so that in the classic theme which uses 1 pixel borders, resize handles are in the content area
     * within the border as they always have been.
     *
     * In the Neptune theme, the handles are embedded into the 5 pixel wide borders of any framed panel.
     */
    $border-width-threshold: 2 !default;

    // ===============================
    // ========= PANEL BODY ==========
    // ===============================
    /**
     * @var {string}
     * The default border-style of Panels
     */
    $panel-body-border-style: solid !default;

    /**
     * @var {color}
     * The default body background-color of Panels
     */
    $panel-body-background-color: #fff !default;

    /**
     * @var {color}
     * The default color of text inside a Panel's body
     */
    $panel-body-color: #000 !default;

    /**
     * @var {color}
     * The default border-color of the Panel body
     */
    $panel-body-border-color: $panel-border-color !default;

    /**
     * @var {number}
     * The default border-width of the Panel body
     */
    $panel-body-border-width: 1px !default;

    /**
     * @var {number}
     * The default font-size of the Panel body
     */
    $panel-body-font-size: $font-size !default;

    /**
     * @var {string}
     * The default font-weight of the Panel body
     */
    $panel-body-font-weight: normal !default;

    /**
     * @var {number}
     * The space between the Panel {@link Ext.panel.Tool Tools}
     */
    $panel-tool-spacing: 4px !default;

    /**
     * @var {string}
     * The background sprite to use for Panel {@link Ext.panel.Tool Tools}
     */
    $panel-tool-background-image: 'tools/tool-sprites' !default;

    /**
     * @var {number}
     * The border-width of Panel Headers
     */
    $panel-header-border-width: $panel-border-width !default;

    /**
     * @var {string}
     * The border-style of Panel Headers
     */
    $panel-header-border-style: solid !default;

    /**
     * @var {number/list}
     * The padding of Panel Headers
     */
    $panel-header-padding: 4px 5px !default;

    /**
     * @var {number}
     * The font-size of Panel Headers
     */
    $panel-header-font-size: $font-size !default;

    /**
     * @var {number}
     * The line-height of Panel Headers
     */
    $panel-header-line-height: 16px !default;

    /**
     * @var {string}
     * The font-weight of Panel Headers
     */
    $panel-header-font-weight: bold !default;

    /**
     * @var {string}
     * The font-family of Panel Headers
     */
    $panel-header-font-family: $font-family !default;

    /**
     * @var {string}
     * The text-transform of Panel Headers
     */
    $panel-header-text-transform: none !default;

    /**
     * @var {number/list}
     * The padding of the Panel Header's text element
     */
    $panel-header-text-padding: 0 !default;

    /**
     * @var {string/list}
     * The background-gradient of the Panel Header. Can be either the name of a predefined
     * gradient or a list of color stops. Used as the `$type` parameter for
     * {@link Global_CSS#background-gradient}.
     */
    $panel-header-background-gradient: null !default;

    /**
     * @var {color}
     * The border-color of the Panel Header
     */
    $panel-header-border-color: $panel-border-color !default;

    /**
     * @var {color}
     * The inner border-color of the Panel Header
     */
    $panel-header-inner-border-color: #fff !default;

    /**
     * @var {number}
     * The inner border-width of the Panel Header
     */
    $panel-header-inner-border-width: 0 !default;

    /**
     * @var {color}
     * The text color of the Panel Header
     */
    $panel-header-color: $color !default;

    /**
     * @var {color}
     * The background-color of the Panel Header
     */
    $panel-header-background-color: $panel-base-color !default;

    /**
     * @var {number}
     * The width of the Panel Header icon
     */
    $panel-header-icon-width: 16px !default;

    /**
     * @var {number}
     * The height of the Panel Header icon
     */
    $panel-header-icon-height: 16px !default;

    /**
     * @var {number}
     * The space between the Panel Header icon and text
     */
    $panel-header-icon-spacing: 4px !default;

    /**
     * @var {list}
     * The background-position of  the Panel Header icon
     */
    $panel-header-icon-background-position: center center !default;

    /**
     * @var {color}
     * The color of the Panel Header glyph icon
     */
    $panel-header-glyph-color: $panel-header-color !default;

    /**
     * @var {number}
     * The opacity of the Panel Header glyph icon
     */
    $panel-header-glyph-opacity: .5 !default;

    /**
     * @var {color}
     * The base color of the framed Panels
     */
    $panel-frame-base-color: $panel-base-color !default;

    /**
     * @var {number}
     * The border-radius of framed Panels
     */
    $panel-frame-border-radius: 4px !default;

    /**
     * @var {number}
     * The border-width of framed Panels
     */
    $panel-frame-border-width: 1px !default;

    /**
     * @var {string}
     * The border-style of framed Panels
     */
    $panel-frame-border-style: solid !default;

    /**
     * @var {number}
     * The padding of framed Panels
     */
    $panel-frame-padding: 4px !default;

    /**
     * @var {color}
     * The background-color of framed Panels
     */
    $panel-frame-background-color: #fff !default;

    /**
     * @var {color}
     * The border-color of framed Panels
     */
    $panel-frame-border-color: $panel-border-color !default;

    /**
     * @var {number}
     * The border-width of the body element of framed Panels
     */
    $panel-frame-body-border-width: 1px !default;

    /**
     * @var {number}
     * The border-width of framed Panel Headers
     */
    $panel-frame-header-border-width: $panel-header-border-width !default;

    /**
     * @var {color}
     * The inner border-color of framed Panel Headers
     */
    $panel-frame-header-inner-border-color: #fff !default;

    /**
     * @var {number}
     * The inner border-width of framed Panel Headers
     */
    $panel-frame-header-inner-border-width: 0 !default;

    /**
     * @var {number/list}
     * The padding of framed Panel Headers
     */
    $panel-frame-header-padding: $panel-header-padding !default;

    /**
     * @var {number}
     * The opacity of ghost Panels while dragging
     */
    $panel-ghost-opacity: 0.50 !default;

    /**
     * @var {string}
     * The direction to strech the background-gradient of top docked Headers when slicing images
     * for IE using Sencha Cmd
     */
    $panel-background-stretch-top: bottom !default;

    /**
     * @var {string}
     * The direction to strech the background-gradient of bottom docked Headers when slicing images
     * for IE using Sencha Cmd
     */
    $panel-background-stretch-bottom: top !default;

    /**
     * @var {string}
     * The direction to strech the background-gradient of right docked Headers when slicing images
     * for IE using Sencha Cmd
     */
    $panel-background-stretch-right: left !default;

    /**
     * @var {string}
     * The direction to strech the background-gradient of left docked Headers when slicing images
     * for IE using Sencha Cmd
     */
    $panel-background-stretch-left: right !default;

    /**
     * @var {boolean}
     * True to include neptune style border management rules.
     */
    $panel-include-border-management-rules: false !default;

    /**
     * @var {color}
     * The color to apply to the border that wraps the body and docked items in a framed
     * panel. The presence of the wrap border in a framed panel is controlled by the
     * {@link #border} config. Only applicable when `$panel-include-border-management-rules` is
     * `true`.
     */
    $panel-wrap-border-color: $panel-border-color !default;

    /**
     * @var {number}
     * The width to apply to the border that wraps the body and docked items in a framed
     * panel. The presence of the wrap border in a framed panel is controlled by the
     * {@link #border} config. Only applicable when `$panel-include-border-management-rules` is
     * `true`.
     */
    $panel-wrap-border-width: 1px !default;

    /**
     * @var {boolean}
     * True to include the "default" panel UI
     */
    $include-panel-default-ui: $include-default-uis !default;

    /**
     * @var {boolean}
     * True to include the "default-framed" panel UI
     */
    $include-panel-default-framed-ui: $include-default-uis !default;