/**
 * Creates a visual theme for a Panel.
 *
 * **Note:** When using `frame: true`, this mixin call creates a UI property with the name and a "-framed" suffix.
 *
 * For example, Panel's UI will be set to "highlight-framed" if `frame:true`.
 *
 * @param {string} $ui
 * The name of the UI being created. Can not included spaces or special punctuation
 * (used in CSS class names).
 * 
 * @param {color} [$ui-border-color=$panel-border-color]
 * The border-color of the Panel
 *
 * @param {number} [$ui-border-radius=$panel-border-radius]
 * The border-radius of the Panel
 *
 * @param {number} [$ui-border-width=$panel-border-width]
 * The border-width of the Panel
 *
 * @param {number} [$ui-padding=$panel-padding]
 * The padding of the Panel
 *
 * @param {color} [$ui-header-color=$panel-header-color]
 * The text color of the Header
 *
 * @param {string} [$ui-header-font-family=$panel-header-font-family]
 * The font-family of the Header
 *
 * @param {number} [$ui-header-font-size=$panel-header-font-size]
 * The font-size of the Header
 *
 * @param {string} [$ui-header-font-weight=$panel-header-font-weight]
 * The font-weight of the Header
 *
 * @param {number} [$ui-header-line-height=$panel-header-line-height]
 * The line-height of the Header
 *
 * @param {color} [$ui-header-border-color=$panel-header-border-color]
 * The border-color of the Header
 *
 * @param {number} [$ui-header-border-width=$panel-header-border-width]
 * The border-width of the Header
 *
 * @param {string} [$ui-header-border-style=$panel-header-border-style]
 * The border-style of the Header
 *
 * @param {color} [$ui-header-background-color=$panel-header-background-color]
 * The background-color of the Header
 *
 * @param {string/list} [$ui-header-background-gradient=$panel-header-background-gradient]
 * The background-gradient of the Header. Can be either the name of a predefined gradient
 * or a list of color stops. Used as the `$type` parameter for {@link Global_CSS#background-gradient}.
 *
 * @param {color} [$ui-header-inner-border-color=$panel-header-inner-border-color]
 * The inner border-color of the Header
 *
 * @param {number} [$ui-header-inner-border-width=$panel-header-inner-border-width]
 * The inner border-width of the Header
 *
 * @param {number/list} [$ui-header-text-padding=$panel-header-text-padding]
 * The padding of the Header's text element
 *
 * @param {number/list} [$ui-header-text-margin=$panel-header-text-margin]
 * The margin of the Header's text element
 *
 * @param {string} [$ui-header-text-transform=$panel-header-text-transform]
 * The text-transform of the Header
 *
 * @param {number/list} [$ui-header-padding=$panel-header-padding]
 * The padding of the Header
 *
 * @param {number} [$ui-header-icon-width=$panel-header-icon-width]
 * The width of the Header icon
 *
 * @param {number} [$ui-header-icon-height=$panel-header-icon-height]
 * The height of the Header icon
 *
 * @param {number} [$ui-header-icon-spacing=$panel-header-icon-spacing]
 * The space between the Header icon and text
 *
 * @param {list} [$ui-header-icon-background-position=$panel-header-icon-background-position]
 * The background-position of the Header icon
 *
 * @param {color} [$ui-header-glyph-color=$panel-header-glyph-color]
 * The color of the Header glyph icon
 *
 * @param {number} [$ui-header-glyph-opacity=$panel-header-glyph-opacity]
 * The opacity of the Header glyph icon
 *
 * @param {number} [$ui-header-noborder-adjust=$panel-header-noborder-adjust]
 * True to adjust the padding of borderless panel headers so that their height is the same
 * as the height of bordered panels.  This is helpful when borderless and bordered panels
 * are used side-by-side, as it maintains a consistent vertical alignment.
 *
 * @param {number} [$ui-tool-spacing=$panel-tool-spacing]
 * The space between the Panel {@link Ext.panel.Tool Tools}
 *
 * @param {string} [$ui-tool-background-image=$panel-tool-background-image]
 * The background sprite to use for Panel {@link Ext.panel.Tool Tools}
 *
 * @param {color} [$ui-tool-glyph-color=$tool-glyph-color]
 * The color to use for tool icons when {@link Global_CSS#$enable-font-icons} is `true`.
 *
 * @param {color} [$ui-tool-focus-outline-color=$panel-tool-focus-outline-color]
 * The color of the outline around Panel {@link Ext.panel.Tool Tools} when focused
 *
 * @param {string} [$ui-tool-focus-outline-style=$panel-tool-focus-outline-style]
 * The outline-style of Panel {@link Ext.panel.Tool Tools} when focused
 *
 * @param {number} [$ui-tool-focus-outline-width=$panel-tool-focus-outline-width]
 * The outline-width of Panel {@link Ext.panel.Tool Tools} when focused
 *
 * @param {number} [$ui-tool-focus-outline-offset=$panel-tool-focus-outline-offset]
 * The outline-offset of Panel {@link Ext.panel.Tool Tools} when focused
 *
 * @param {color} [$ui-body-color=$panel-body-color]
 * The color of text inside the Panel body
 *
 * @param {color} [$ui-body-border-color=$panel-body-border-color]
 * The border-color of the Panel body
 *
 * @param {number} [$ui-body-border-width=$panel-body-border-width]
 * The border-width of the Panel body
 *
 * @param {string} [$ui-body-border-style=$panel-body-border-style]
 * The border-style of the Panel body
 *
 * @param {color} [$ui-body-background-color=$panel-body-background-color]
 * The background-color of the Panel body
 *
 * @param {number} [$ui-body-font-size=$panel-body-font-size]
 * The font-size of the Panel body
 *
 * @param {string} [$ui-body-font-weight=$panel-body-font-weight]
 * The font-weight of the Panel body
 *
 * @param {string} [$ui-background-stretch-top=$panel-background-stretch-top]
 * The direction to strech the background-gradient of top docked Headers when slicing images
 * for IE using Sencha Cmd
 *
 * @param {string} [$ui-background-stretch-bottom=$panel-background-stretch-bottom]
 * The direction to strech the background-gradient of bottom docked Headers when slicing images
 * for IE using Sencha Cmd
 *
 * @param {string} [$ui-background-stretch-right=$panel-background-stretch-right]
 * The direction to strech the background-gradient of right docked Headers when slicing images
 * for IE using Sencha Cmd
 *
 * @param {string} [$ui-background-stretch-left=$panel-background-stretch-left]
 * The direction to strech the background-gradient of left docked Headers when slicing images
 * for IE using Sencha Cmd
 *
 * @param {boolean} [$ui-include-border-management-rules=$panel-include-border-management-rules]
 * True to include neptune style border management rules.
 *
 * @param {color} [$ui-wrap-border-color=$panel-wrap-border-color]
 * The color to apply to the border that wraps the body and docked items in a framed
 * panel. The presence of the wrap border in a framed panel is controlled by the
 * {@link #border} config. Only applicable when `$ui-include-border-management-rules` is
 * `true`.
 *
 * @param {color} [$ui-wrap-border-width=$panel-wrap-border-width]
 * 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 `$ui-include-border-management-rules` is
 * `true`.
 *
 * @param {boolean} [$ui-ignore-frame-padding=$panel-ignore-frame-padding]
 * True to ignore the frame padding.  By default, the frame mixin adds extra padding when
 * border radius is larger than border width.  This is intended to prevent the content
 * from colliding with the rounded corners of the frame.  Set this to true to prevent
 * the panel frame from adding this extra padding.
 *
 * @member Ext.panel.Panel
 */
@mixin extjs-panel-ui(
    $ui: null,

    $ui-border-color: $panel-border-color,
    $ui-border-radius: $panel-border-radius,
    $ui-border-width: $panel-border-width,
    $ui-padding: 0,

    $ui-header-color: $panel-header-color,
    $ui-header-font-family: $panel-header-font-family,
    $ui-header-font-size: $panel-header-font-size,
    $ui-header-font-weight: $panel-header-font-weight,
    $ui-header-line-height: $panel-header-line-height,
    $ui-header-border-color: $panel-header-border-color,
    $ui-header-border-width: $panel-header-border-width,
    $ui-header-border-style: $panel-header-border-style,
    $ui-header-background-color: $panel-header-background-color,
    $ui-header-background-gradient: $panel-header-background-gradient,
    $ui-header-inner-border-color: $panel-header-inner-border-color,
    $ui-header-inner-border-width: $panel-header-inner-border-width,
    $ui-header-text-padding: $panel-header-text-padding,
    $ui-header-text-margin: $panel-header-text-margin,
    $ui-header-text-transform: $panel-header-text-transform,
    $ui-header-padding: $panel-header-padding,
    $ui-header-icon-width: $panel-header-icon-width,
    $ui-header-icon-height: $panel-header-icon-height,
    $ui-header-icon-spacing: $panel-header-icon-spacing,
    $ui-header-icon-background-position: $panel-header-icon-background-position,
    $ui-header-glyph-color: $panel-header-glyph-color,
    $ui-header-glyph-opacity: $panel-header-glyph-opacity,
    $ui-header-noborder-adjust: $panel-header-noborder-adjust,

    $ui-tool-spacing: $panel-tool-spacing,
    $ui-tool-background-image: $panel-tool-background-image,
    $ui-tool-glyph-color: $tool-glyph-color,
    $ui-tool-focus-outline-color: $panel-tool-focus-outline-color,
    $ui-tool-focus-outline-style: $panel-tool-focus-outline-style,
    $ui-tool-focus-outline-width: $panel-tool-focus-outline-width,
    $ui-tool-focus-outline-offset: $panel-tool-focus-outline-offset,

    $ui-body-color: $panel-body-color,
    $ui-body-border-color: $panel-body-border-color,
    $ui-body-border-width: $panel-body-border-width,
    $ui-body-border-style: $panel-body-border-style,
    $ui-body-background-color: $panel-body-background-color,
    $ui-body-font-size: $panel-body-font-size,
    $ui-body-font-weight: $panel-body-font-weight,
    $ui-body-font-family: $panel-body-font-family,

    $ui-background-stretch-top: $panel-background-stretch-top,
    $ui-background-stretch-bottom: $panel-background-stretch-bottom,
    $ui-background-stretch-right: $panel-background-stretch-right,
    $ui-background-stretch-left: $panel-background-stretch-left,

    // See the docs above
    $ui-include-border-management-rules: $panel-include-border-management-rules,
    $ui-wrap-border-color: null,
    $ui-wrap-border-width: null,
    $ui-ignore-frame-padding: $panel-ignore-frame-padding,

    // deprecated - use $ui instead
    $ui-label: null
){
    @if $ui == null {
        @if $ui-label != null {
            @warn '$ui-label is deprecated.  Use $ui instead';
            $ui: $ui-label;
        } @else {
            @warn "#{error('$ui is required')}";
        }
    }

    @if is-null($ui-wrap-border-color) {
        @if $ui == 'default-framed' {
            $ui-wrap-border-color: $panel-wrap-border-color;
        } @else {
            $ui-wrap-border-color: $ui-border-color;
        }
    }

    @if is-null($ui-wrap-border-width) {
        @if $ui == 'default-framed' {
            $ui-wrap-border-width: $panel-wrap-border-width;
        } @else {
            $ui-wrap-border-width: $ui-border-width;
        }
    }

    @if is-null($ui-header-inner-border-color) and not is-null($ui-header-background-color) {
        $ui-header-inner-border-color: lighten($ui-header-background-color, 10);
    }

    $ui-header-padding-noborder:
        top($ui-header-padding) + top($ui-header-border-width)
        right($ui-header-padding) + right($ui-header-border-width)
        // don't add bottom border since bottom border always gets removed by dock layout
        bottom($ui-header-padding)
        left($ui-header-padding) + left($ui-header-border-width);

    .#{$prefix}panel-#{$ui} {
        @if not is-null($ui-border-color) { border-color: $ui-border-color; }
        padding: $ui-padding;
    }

    // header
    .#{$prefix}panel-header-#{$ui} {
        @if not is-null($ui-header-font-size) { font-size: $ui-header-font-size; }

        @if $ui-header-border-width != 0 {
            border: $ui-header-border-width $ui-header-border-style $ui-header-border-color;
        }

        @if $enable-font-icons {
            @if $ui-tool-glyph-color != $tool-glyph-color {
                .#{$prefix}tool-tool-el {
                    color: $ui-tool-glyph-color;
                }
            }
        } @else {
            .#{$prefix}tool-img {
                @if $ui-tool-background-image != $tool-background-image {
                    background-image: theme-background-image($ui-tool-background-image);
                }
            }
        }

        @if is-null($ui-header-background-gradient) {
            // EXTJSIV-8846: partially transparent png images do not display correctly
            // in winXP/IE8 when the image element has a transparent background.
            // to fix this, we give the element the same background-color as the header.
            .#{$prefix}tool-tool-el {
                background-color: $ui-header-background-color;
            }
        }
    }

    .#{$prefix}panel-header-#{$ui}-horizontal {
        padding: $ui-header-padding;

        @if $include-ext-tab-bar {
            .#{$prefix}panel-header-#{$ui}-tab-bar {
                margin-top: -(top($ui-header-padding));
                margin-bottom: -(bottom($ui-header-padding));
            }
        }
    }

    @if $ui-header-noborder-adjust {
        .#{$prefix}panel-header-#{$ui}-horizontal.#{$prefix}header-noborder {
            padding: $ui-header-padding-noborder;

            @if $include-ext-tab-bar {
                .#{$prefix}panel-header-#{$ui}-tab-bar {
                    margin-top: -(top($ui-header-padding-noborder));
                    margin-bottom: -(bottom($ui-header-padding-noborder));
                }
            }
        }
    }

    .#{$prefix}panel-header-#{$ui}-vertical {
        padding: rotate90($ui-header-padding);

        @if $include-ext-tab-bar {
            .#{$prefix}panel-header-#{$ui}-tab-bar {
                margin-right: -(top($ui-header-padding));
                margin-left: -(bottom($ui-header-padding));
            }
        }
    }

    @if $ui-header-noborder-adjust {
        .#{$prefix}panel-header-#{$ui}-vertical.#{$prefix}header-noborder {
            padding: rotate90($ui-header-padding-noborder);

            @if $include-ext-tab-bar {
                .#{$prefix}panel-header-#{$ui}-tab-bar {
                    margin-right: -(top($ui-header-padding-noborder));
                    margin-left: -(bottom($ui-header-padding-noborder));
                }
            }
        }
    }

    @if $include-rtl {
        .#{$prefix}rtl.#{$prefix}panel-header-#{$ui}-vertical {
            padding: rotate270($ui-header-padding);

            @if $include-ext-tab-bar {
                .#{$prefix}panel-header-#{$ui}-tab-bar {
                    margin-left: -(top($ui-header-padding));
                    margin-right: -(bottom($ui-header-padding));
                }
            }
        }

        @if $ui-header-noborder-adjust {
            .#{$prefix}rtl.#{$prefix}panel-header-#{$ui}-vertical.#{$prefix}header-noborder {
                padding: rotate270($ui-header-padding-noborder);

                @if $include-ext-tab-bar {
                    .#{$prefix}panel-header-#{$ui}-tab-bar {
                        margin-left: -(top($ui-header-padding-noborder));
                        margin-right: -(bottom($ui-header-padding-noborder));
                    }
                }
            }
        }
    }

    .#{$prefix}panel-header-title-#{$ui} {
        @if not is-null($ui-header-color) { color: $ui-header-color; }

        @if not is-null($ui-header-font-size) {   font-size: $ui-header-font-size; }
        @if not is-null($ui-header-font-weight) { font-weight: $ui-header-font-weight; }
        @if not is-null($ui-header-font-family) { font-family: $ui-header-font-family; }
        @if not is-null($ui-header-line-height) { line-height: $ui-header-line-height; }

        @if $ui-header-text-margin != 0 {
            margin: $ui-header-text-margin;
        }

        > {
            .#{$prefix}title-text-#{$ui} {
                text-transform: $ui-header-text-transform;
                padding: $ui-header-text-padding;

                @if $ext-trial {
                    &:after {
                        font-family: ext-watermark;
                        font-size: ($ui-header-line-height + vertical($ui-header-padding)) * 0.75;
                        content: 'd';
                        position: absolute;
                        top: 0;
                        right: 0;
                        // since IE8 does not support opacity on pseudo elements we simulate it by
                        // mixing the text color with the background color
                        color: mix($ui-header-color, $ui-header-background-color, 40%);
                    }

                    @if $include-rtl {
                        &.#{$prefix}rtl:after {
                            right: auto;
                            left: 0;
                        }
                    }
                }
                @if $ext-beta {
                    &:after {
                        font-family: ext-watermark;
                        font-size: ($ui-header-line-height + vertical($ui-header-padding)) * 0.75;
                        content: 'b';
                        position: absolute;
                        top: 0;
                        right: 0;
                        // since IE8 does not support opacity on pseudo elements we simulate it by
                        // mixing the text color with the background color
                        color: mix($ui-header-color, $ui-header-background-color, 40%);
                    }

                    @if $include-rtl {
                        &.#{$prefix}rtl:after {
                            right: auto;
                            left: 0;
                        }
                    }
                }
            }

            .#{$prefix}title-icon-wrap-#{$ui} {
                &.#{$prefix}title-icon-top {
                    height: $ui-header-icon-height + $ui-header-icon-spacing;
                    padding-bottom: $ui-header-icon-spacing;
                }

                &.#{$prefix}title-icon-right {
                    width: $ui-header-icon-width + $ui-header-icon-spacing;
                    padding-left: $ui-header-icon-spacing;

                    @if $include-rtl {
                        &.#{$prefix}rtl {
                            padding-left: 0;
                            padding-right: $ui-header-icon-spacing;
                        }
                    }
                }

                &.#{$prefix}title-icon-bottom {
                    height: $ui-header-icon-height + $ui-header-icon-spacing;
                    padding-top: $ui-header-icon-spacing;
                }

                &.#{$prefix}title-icon-left {
                    width: $ui-header-icon-width + $ui-header-icon-spacing;
                    padding-right: $ui-header-icon-spacing;

                    @if $include-rtl {
                        &.#{$prefix}rtl {
                            padding-right: 0;
                            padding-left: $ui-header-icon-spacing;
                        }
                    }
                }

                > .#{$prefix}title-icon-#{$ui} {
                    width: $ui-header-icon-width;
                    height: $ui-header-icon-height;
                    font-size: $ui-header-icon-height;
                    color: $ui-header-glyph-color;
                    background-position: $ui-header-icon-background-position;

                    &.#{$prefix}title-glyph {
                        @if $ui-header-glyph-opacity != 1 {
                            // do not use the opacity mixin because we do not want IE's filter version of
                            // opacity to be included.  We emulate the opacity setting in IE8m by mixing
                            // the icon color into the background color. (see below)
                            opacity: $ui-header-glyph-opacity;
                        }
                        // In IE8 and below when a glyph contains partially transparent pixels, we
                        // can't apply an opacity filter to the glyph element, because IE8m will render
                        // the partially transparent pixels of the glyph as black. To work around this,
                        // we emulate the approximate color that the glyph would have if it had opacity
                        // applied by mixing the glyph color with the header's background-color.
                        @if $include-ie {
                            .#{$prefix}ie8 & {
                                color: mix($ui-header-glyph-color, $ui-header-background-color, $ui-header-glyph-opacity * 100);
                            }
                        }
                    }
                }
            }
        }
    }

    // body
    .#{$prefix}panel-body-#{$ui} {
        @if not is-null($ui-body-background-color) { background: $ui-body-background-color; }
        @if not is-null($ui-body-border-color) {     border-color: $ui-body-border-color; }
        @if not is-null($ui-body-color) {            color: $ui-body-color; }
        @if not is-null($ui-body-font-size) {        font-size: $ui-body-font-size; }
        @if not is-null($ui-body-font-weight) {      font-weight: $ui-body-font-weight; }
        @if not is-null($ui-body-font-family) {      font-family: $ui-body-font-family; }

        @if not is-null($ui-body-border-width) {
            border-width: $ui-body-border-width;
            @if not is-null($ui-body-border-style) { border-style: $ui-body-border-style; }
        }
    }

    @if not is-null($ui-border-radius) and $ui-border-radius != 0 {
        @include x-frame(
            $cls: 'panel',
            $ui: '#{$ui}',
            $border-radius: $ui-border-radius,
            $border-width: $ui-border-width,
            $padding: $ui-padding,
            $background-color: $ui-body-background-color,
            $ignore-frame-padding: $ui-ignore-frame-padding
        );

        @include x-frame(
            $cls: 'panel-header',
            $ui: '#{$ui}-top',
            $border-radius: top($ui-border-radius) right($ui-border-radius) 0 0,
            $border-width: top($ui-header-border-width) right($ui-header-border-width) 0 left($ui-header-border-width),
            $padding: $ui-header-padding,
            $background-color: $ui-header-background-color,
            $background-gradient: $ui-header-background-gradient,
            $background-stretch: $ui-background-stretch-top
        );

        @include x-frame(
            $cls: 'panel-header',
            $ui: '#{$ui}-right',
            $border-radius: 0 right($ui-border-radius) bottom($ui-border-radius) 0,
            $border-width: top($ui-header-border-width) right($ui-header-border-width) bottom($ui-header-border-width) 0,
            $padding: rotate90($ui-header-padding),
            $background-color: $ui-header-background-color,
            $background-gradient: $ui-header-background-gradient,
            $background-direction: right,
            $include-frame-rtl: $include-rtl,
            $background-stretch: $ui-background-stretch-right
        );

        @include x-frame(
            $cls: 'panel-header',
            $ui: '#{$ui}-bottom',
            $border-radius: 0 0 bottom($ui-border-radius) left($ui-border-radius),
            $border-width: 0 right($ui-header-border-width) bottom($ui-header-border-width) left($ui-header-border-width),
            $padding: $ui-header-padding,
            $background-color: $ui-header-background-color,
            $background-gradient: $ui-header-background-gradient,
            $background-stretch: $ui-background-stretch-bottom
        );

        @include x-frame(
            $cls: 'panel-header',
            $ui: '#{$ui}-left',
            $border-radius: top($ui-border-radius) 0 0 left($ui-border-radius),
            $border-width: top($ui-header-border-width) 0 bottom($ui-header-border-width) left($ui-header-border-width),
            $padding: rotate90($ui-header-padding),
            $background-color: $ui-header-background-color,
            $background-gradient: $ui-header-background-gradient,
            $background-direction: right,
            $include-frame-rtl: $include-rtl,
            $background-stretch: $ui-background-stretch-left
        );

        @include x-frame(
            $cls: 'panel-header',
            $ui: '#{$ui}-collapsed-top',
            $border-radius: top($ui-border-radius) right($ui-border-radius) bottom($ui-border-radius) left($ui-border-radius),
            $border-width: $ui-header-border-width,
            $padding: $ui-header-padding,
            $background-color: $ui-header-background-color,
            $background-gradient: $ui-header-background-gradient,
            $background-stretch: $ui-background-stretch-top
        );

        @include x-frame(
            $cls: 'panel-header',
            $ui: '#{$ui}-collapsed-right',
            $border-radius: top($ui-border-radius) right($ui-border-radius) bottom($ui-border-radius) left($ui-border-radius),
            $border-width: $ui-header-border-width,
            $padding: rotate90($ui-header-padding),
            $background-color: $ui-header-background-color,
            $background-gradient: $ui-header-background-gradient,
            $background-direction: right,
            $include-frame-rtl: $include-rtl,
            $background-stretch: $ui-background-stretch-right
        );

        @include x-frame(
            $cls: 'panel-header',
            $ui: '#{$ui}-collapsed-bottom',
            $border-radius: top($ui-border-radius) right($ui-border-radius) bottom($ui-border-radius) left($ui-border-radius),
            $border-width: $ui-header-border-width,
            $padding: $ui-header-padding,
            $background-color: $ui-header-background-color,
            $background-gradient: $ui-header-background-gradient,
            $background-stretch: $ui-background-stretch-bottom
        );

        @include x-frame(
            $cls: 'panel-header',
            $ui: '#{$ui}-collapsed-left',
            $border-radius: top($ui-border-radius) right($ui-border-radius) bottom($ui-border-radius) left($ui-border-radius),
            $border-width: $ui-header-border-width,
            $padding: rotate90($ui-header-padding),
            $background-color: $ui-header-background-color,
            $background-gradient: $ui-header-background-gradient,
            $background-direction: right,
            $include-frame-rtl: $include-rtl,
            $background-stretch: $ui-background-stretch-left
        );

        // !important is needed in the following rules to override dock layout's border
        // management rules. the x-panel ancestor selector is used to increase the
        // specificity over the ".#{$prefix}nbr .#{$prefix}#{$cls-ui}" rule produced by
        // x-frame
        .#{$prefix}panel {
            .#{$prefix}panel-header-#{$ui}-top {
                border-bottom-width: bottom($ui-header-border-width) !important;
            }

            .#{$prefix}panel-header-#{$ui}-right {
                border-left-width: bottom($ui-header-border-width) !important;
            }

            .#{$prefix}panel-header-#{$ui}-bottom {
                border-top-width: bottom($ui-header-border-width) !important;
            }

            .#{$prefix}panel-header-#{$ui}-left {
                border-right-width: bottom($ui-header-border-width) !important;
            }
        }
        @if $include-slicer-border-radius {
            .#{$prefix}nbr {
                .#{$prefix}panel-header-#{$ui}-collapsed-top {
                    border-bottom-width: 0 !important;
                }

                .#{$prefix}panel-header-#{$ui}-collapsed-right {
                    border-left-width: 0 !important;
                }

                .#{$prefix}panel-header-#{$ui}-collapsed-bottom {
                    border-top-width: 0 !important;
                }

                .#{$prefix}panel-header-#{$ui}-collapsed-left {
                    border-right-width: 0 !important;
                }
            }
        }

    } @else {
        @if not is-null($ui-header-background-color) {
            .#{$prefix}panel-header-#{$ui} {
                @include background-gradient($ui-header-background-color, $ui-header-background-gradient);
            }

            .#{$prefix}panel-header-#{$ui}-vertical {
                @include background-gradient($ui-header-background-color, $ui-header-background-gradient, right);
            }

            @if $include-rtl {
                .#{$prefix}rtl.#{$prefix}panel-header-#{$ui}-vertical {
                    @include background-gradient($ui-header-background-color, $ui-header-background-gradient, left);
                }
            }
        }

        // header background images
        $panel-header-ui: 'panel-header-#{$ui}';
        $panel-header-path: 'panel-header/panel-header-#{$ui}';

        @if not is-null($ui-header-background-color) and not is-null($ui-header-background-gradient) {
            @if $include-slicer-gradient {
                .#{$prefix}nlg {
                    .#{$prefix}#{$panel-header-ui}-top {
                        background: slicer-background-image($panel-header-ui + '-top',
                                            '#{$panel-header-path}-top-bg');
                    }

                    .#{$prefix}#{$panel-header-ui}-bottom {
                        background: slicer-background-image($panel-header-ui + '-bottom',
                                            '#{$panel-header-path}-bottom-bg') bottom left;
                    }

                    .#{$prefix}#{$panel-header-ui}-left {
                        background: slicer-background-image($panel-header-ui + '-left',
                                            '#{$panel-header-path}-left-bg') top left;
                    }

                    .#{$prefix}#{$panel-header-ui}-right {
                        background: slicer-background-image($panel-header-ui + '-right',
                                            '#{$panel-header-path}-right-bg') top right;
                    }

                    @if $include-rtl {
                        .#{$prefix}rtl {
                            &.#{$prefix}#{$panel-header-ui}-left {
                                background: slicer-background-image-rtl($panel-header-ui + '-left',
                                            '#{$panel-header-path}-left-bg-rtl') top right;
                            }
                            &.#{$prefix}#{$panel-header-ui}-right {
                                background: slicer-background-image-rtl($panel-header-ui + '-right',
                                            '#{$panel-header-path}-right-bg-rtl') top left;
                            }
                        }
                    }
                }
            }
        }

        .#{$prefix}panel {
            // !important is needed here to override dock layout's border management
            // rules. the x-panel ancestor selector is used to increase the specificity
            // over the ".#{$prefix}nbr .#{$prefix}#{$cls-ui}" rule produced by x-frame
            .#{$prefix}panel-header-#{$ui}-collapsed-border-top {
                border-bottom-width: $ui-header-border-width !important;
            }

            .#{$prefix}panel-header-#{$ui}-collapsed-border-right {
                border-left-width: $ui-header-border-width !important;
            }

            .#{$prefix}panel-header-#{$ui}-collapsed-border-bottom {
                border-top-width: $ui-header-border-width !important;
            }

            .#{$prefix}panel-header-#{$ui}-collapsed-border-left {
                border-right-width: $ui-header-border-width !important;
            }
        }

        $stretch: slicer-background-stretch($panel-header-ui + '-top', $ui-background-stretch-top);
        $stretch: slicer-background-stretch($panel-header-ui + '-right', $ui-background-stretch-right);
        $stretch: slicer-background-stretch($panel-header-ui + '-bottom', $ui-background-stretch-bottom);
        $stretch: slicer-background-stretch($panel-header-ui + '-left', $ui-background-stretch-left);

        @include x-slicer($panel-header-ui + '-top');
        @include x-slicer($panel-header-ui + '-bottom');
        @include x-slicer($panel-header-ui + '-left');
        @include x-slicer($panel-header-ui + '-right');
    }

    @if $ui-header-inner-border-width != 0 {
        .#{$prefix}panel-header-#{$ui}-top {
            @include inner-border($ui-header-inner-border-width, $ui-header-inner-border-color);
        }

        .#{$prefix}panel-header-#{$ui}-right {
            @include inner-border(rotate90($ui-header-inner-border-width), $ui-header-inner-border-color);
        }

        .#{$prefix}panel-header-#{$ui}-bottom {
            @include inner-border(rotate180($ui-header-inner-border-width), $ui-header-inner-border-color);
        }

        .#{$prefix}panel-header-#{$ui}-left {
            @include inner-border(rotate270($ui-header-inner-border-width), $ui-header-inner-border-color);
        }
    }

    $ui-tool-margin: 0 0 0 $ui-tool-spacing;
    .#{$prefix}panel-header-#{$ui}-horizontal {
        .#{$prefix}tool-after-title {
            margin: $ui-tool-margin;
        }

        @if $include-rtl {
            .#{$prefix}rtl.#{$prefix}tool-after-title {
                margin: rtl($ui-tool-margin);
            }
        }

        .#{$prefix}tool-before-title {
            margin: rtl($ui-tool-margin);
        }

        @if $include-rtl {
            .#{$prefix}rtl.#{$prefix}tool-before-title {
                margin: $ui-tool-margin;
            }
        }
    }

    .#{$prefix}panel-header-#{$ui}-vertical {
        .#{$prefix}tool-after-title {
            margin: rotate90($ui-tool-margin);
        }

        @if $include-rtl {
            .#{$prefix}rtl.#{$prefix}tool-after-title {
                margin: rotate270(rtl($ui-tool-margin));
            }
        }

        .#{$prefix}tool-before-title {
            margin: rotate90(rtl($ui-tool-margin));
        }

        @if $include-rtl {
            .#{$prefix}rtl.#{$prefix}tool-before-title {
                margin: rotate270($ui-tool-margin);
            }
        }
    }

    .#{$prefix}panel-header-#{$ui} {
        .#{$prefix}tool-focus {
            @include css-outline(
                $width: $ui-tool-focus-outline-width,
                $style: $ui-tool-focus-outline-style,
                $color: $ui-tool-focus-outline-color,
                $offset: $ui-tool-focus-outline-offset
            );
        }
    }

    @if $include-rtl {
        .#{$prefix}rtl {
            &.#{$prefix}panel-header-#{$ui}-collapsed-border-right {
                border-right-width: $ui-header-border-width !important;
            }
            &.#{$prefix}panel-header-#{$ui}-collapsed-border-left {
                border-left-width: $ui-header-border-width !important;
            }
        }
    }

    // Panel resizing.
    // If there's a border that's wider than the specified threshold (Sencha default is 2) then
    // embed the handles in the borders using -ve position and make resizable windows show overflow.
    // The dock layout should ensure that all constituent elements fit within the element.
    // The only exception is during animated resizing. Overflow inline style is set hidden during animation (AbstractComponent.animate)
    .#{$prefix}panel-#{$ui}-resizable {

        // Panel resize handles are invisible
        .#{$prefix}panel-handle {
            @include opacity(0);
        }

        // If there's a border width, embed the handles in that border
        @if $ui-border-width > $border-width-threshold {
            // Resizable Panel element overflow must be visible for embedded handles to accept mouseovers.
            overflow: visible;

            .#{$prefix}panel-handle-north-br {
                top: -($ui-border-width);
            }
            .#{$prefix}panel-handle-south-br {
                bottom: -($ui-border-width);
            }
            .#{$prefix}panel-handle-east-br {
                right: -($ui-border-width);
            }
            .#{$prefix}panel-handle-west-br {
                left: -($ui-border-width);
            }
            .#{$prefix}panel-handle-northwest-br {
                left: -($ui-border-width);
                top: -($ui-border-width);
            }
            .#{$prefix}panel-handle-northeast-br {
                right: -($ui-border-width);
                top: -($ui-border-width);
            }
            .#{$prefix}panel-handle-southeast-br {
                right: -($ui-border-width);
                bottom: -($ui-border-width);
            }
            .#{$prefix}panel-handle-southwest-br {
                left: -($ui-border-width);
                bottom: -($ui-border-width);
            }
        }
    }

    @if $ui-include-border-management-rules {
        @include border-management(
            $parent-cls: panel-#{$ui},
            $border-width: $ui-wrap-border-width,
            $border-color: $ui-wrap-border-color
        );
    }
}

.#{$prefix}panel-ghost {
    @include opacity($panel-ghost-opacity);
}

@if $include-panel-default-ui {
    @include extjs-panel-ui(
        $ui: 'default'
    );
}

@if $include-panel-default-framed-ui {
    @include extjs-panel-ui(
        $ui: 'default-framed',

        $ui-border-color: $panel-frame-border-color,
        $ui-border-width: $panel-frame-border-width,
        $ui-border-radius: $panel-frame-border-radius,
        $ui-padding: $panel-frame-padding,

        $ui-header-border-color: $panel-frame-border-color,
        $ui-header-border-width: $panel-frame-header-border-width,
        $ui-header-inner-border-color: $panel-frame-header-inner-border-color,
        $ui-header-inner-border-width: $panel-frame-header-inner-border-width,
        $ui-header-padding: $panel-frame-header-padding,

        $ui-body-border-width: $panel-frame-body-border-width,
        $ui-body-background-color: $panel-frame-background-color
    );
}
