How to measure/convert CSS text margin/padding in the Photoshop?

Finally, the script for measuring vertical distance is finished! It can correctly calculate the vertical distance for CSS between layers, one of which or both are text layers.

Here's the link on Adobe Forums - A script for measuring the distance between two elements?

// version no CS6 or no effects

var old_units = app.preferences.rulerUnits;    
app.preferences.rulerUnits = Units.PIXELS;    

try { app.activeDocument.suspendHistory("Get Text Bounds", "var bounds = get_selected_layers_bounds()") } catch(e) { alert(e); }  

try { executeAction( charIDToTypeID( "undo" ), undefined, DialogModes.NO ); } catch(e) { alert(e); }  

app.preferences.rulerUnits = old_units;    

if (bounds)    
    {    
    if (bounds.length == 2)    
        {    
        var distance = 0;

        if (bounds[0].bottom <= bounds[1].top) distance = bounds[1].top - bounds[0].bottom;    
        else if (bounds[1].bottom <= bounds[0].top) distance = bounds[0].top - bounds[1].bottom;    

        else  alert("Intersecting layers")    

        var distance_in_css = distance - (bounds[0].leading - 1.2*bounds[0].size)/2 - (bounds[1].leading - 1.2*bounds[1].size)/2;

        alert("distance = " + distance + "ndistance_in_css = " + distance_in_css);
        }    
    else    
        alert("More then 2 selected layers")     

    }    
else     
    alert("There is no selected layers")     

/////////////////////////////////////////////////////////////////////////////////////////////////    
function get_selected_layers_bounds()    
    {    
    try {    
        var ref = new ActionReference();    

        ref.putProperty( charIDToTypeID( "Prpr" ), stringIDToTypeID( "targetLayers" ) );    
        ref.putEnumerated( charIDToTypeID("Dcmn"), charIDToTypeID("Ordn"), charIDToTypeID("Trgt") );    
        var desc = executeActionGet(ref);    

        if (!desc.hasKey( stringIDToTypeID("targetLayers") ) ) return null;    

        var n = 0;    
        try { activeDocument.backgroundLayer } catch (e) { n = 1; }    

        desc = desc.getList( stringIDToTypeID("targetLayers"));    

        var len = desc.count;    

        var selected_bounds = new Array();    

        for (var i = 0; i < len; i++)    
            {    
            try     
                {    
                var r = new ActionReference();    
                r.putIndex( charIDToTypeID( "Lyr " ), desc.getReference(i).getIndex() + n);    

                var ret = executeActionGet(r);    

                var size    = 0;
                var leading = 0;

                if (ret.hasKey(stringIDToTypeID("textKey")))  
                    {  
                    var textStyleRangeList = ret.getObjectValue(stringIDToTypeID("textKey")).getList(charIDToTypeID("Txtt" ));

                    if (textStyleRangeList.count > 1) { alert("More than one textStyleRange in layer", "Oops!!"); }

                    var textStyle = textStyleRangeList.getObjectValue(0).getObjectValue(charIDToTypeID("TxtS" ));

                    var auto_leading = textStyle.getBoolean(stringIDToTypeID("autoLeading"));

                    size = textStyle.getUnitDoubleValue(stringIDToTypeID("size"));
                    leading = auto_leading?size*1.2:textStyle.getUnitDoubleValue(stringIDToTypeID("leading"));

                    var s = ret.getObjectValue(stringIDToTypeID("textKey")).getString(charIDToTypeID("Txt " ));  
                    s = s.replace(/^./gm, String.fromCharCode(0x2588));  

                    var d1 = new ActionDescriptor();  
                    d1.putReference( charIDToTypeID( "null" ), r );  

                    var d2 = new ActionDescriptor();  
                    d2.putString( charIDToTypeID( "Txt " ), s);  

                    d1.putObject( charIDToTypeID( "T   " ), charIDToTypeID( "TxLr" ), d2 );  

                    executeAction( charIDToTypeID( "setd" ), d1, DialogModes.NO );  

                    ret = executeActionGet(r);    
                    }  


                // var bounds = ret.getObjectValue(stringIDToTypeID("bounds"));  // use this in CS6 or when you want to take into account the effects    

                var bounds = ret.getObjectValue(stringIDToTypeID("boundsNoEffects")); // in CS6 does not work    

                var obj = { 
                          left   : bounds.getUnitDoubleValue(stringIDToTypeID("left")),    
                          top    : bounds.getUnitDoubleValue(stringIDToTypeID("top")),    
                          right  : bounds.getUnitDoubleValue(stringIDToTypeID("right")),    
                          bottom : bounds.getUnitDoubleValue(stringIDToTypeID("bottom")),
                          size   : size,
                          leading: leading,
                          };    

                    selected_bounds.push(obj);    
                }

                catch (e) { alert(e); return null; }    
            }    

            return selected_bounds;    
        }    

    catch (e) { alert(e); return null; }    
}

The script should be saved as a *.js or *.jsx file (for example, distance.js) in the Photoshop folder - C:Program FilesAdobeAdobe Photoshop CC 2017PresetsScripts

It will be available in the Photoshop menu - File > Scripts > Distance