Support margin style flag

document.go

@@ -26,21 +26,29 @@ func (e *DocumentElement) Finish(w io.Writer, node *bf.Node, tr *TermRenderer) e
 		indent = rules.Indent
 		suffix = rules.Suffix
 	}
-
+	pw := &PaddingWriter{
+		Padding: uint(tr.WordWrap + int(indent*2)),
+		PadFunc: func(wr io.Writer) {
+			renderText(w, rules, " ")
+		},
+		Forward: &AnsiWriter{
+			Forward: w,
+		},
+	}
 	iw := &IndentWriter{
 		Indent: indent,
 		Forward: &AnsiWriter{
-			Forward: w,
+			Forward: pw,
 		},
 	}
 	_, err := iw.Write(tr.document.Bytes())
 	if err != nil {
 		return err
 	}
+	renderText(iw, rules, suffix)
 
 	tr.document.Reset()
 	tr.blockStyle.Pop()
 
-	renderText(w, rules, suffix)
 	return nil
 }

style.go

@@ -49,6 +49,7 @@ type ElementStyle struct {
 	Inverse         bool   `json:"inverse"`
 	Blink           bool   `json:"blink"`
 	Indent          uint   `json:"indent"`
+	Margin          uint   `json:"margin"`
 	Theme           string `json:"theme"`
 	Prefix          string `json:"prefix"`
 	Suffix          string `json:"suffix"`
@@ -83,6 +84,19 @@ func (s StyleStack) Indent() uint {
 	return i
 }
 
+func (s StyleStack) Margin() uint {
+	var i uint
+
+	for _, v := range s {
+		if v == nil {
+			continue
+		}
+		i += v.Margin
+	}
+
+	return i
+}
+
 func (s StyleStack) Parent() *ElementStyle {
 	if len(s) < 2 {
 		return s.Current()