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@@ -855,15 +855,15 @@
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// If this slide has a background color, add a class that
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// signals if it is light or dark. If the slide has no background
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// color, no class will be set
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- var computedBackgroundColor = window.getComputedStyle( element ).backgroundColor;
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- if( computedBackgroundColor ) {
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- var rgb = colorToRgb( computedBackgroundColor );
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+ var computedBackgroundStyle = window.getComputedStyle( element );
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+ if( computedBackgroundStyle && computedBackgroundStyle.backgroundColor ) {
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+ var rgb = colorToRgb( computedBackgroundStyle.backgroundColor );
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// Ignore fully transparent backgrounds. Some browsers return
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// rgba(0,0,0,0) when reading the computed background color of
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// an element with no background
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if( rgb && rgb.a !== 0 ) {
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- if( colorBrightness( computedBackgroundColor ) < 128 ) {
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+ if( colorBrightness( computedBackgroundStyle.backgroundColor ) < 128 ) {
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slide.classList.add( 'has-dark-background' );
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}
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else {
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