diff --git a/cmd/main/main.go b/cmd/main/main.go
index 02703e0..883b280 100644
--- a/cmd/main/main.go
+++ b/cmd/main/main.go
@@ -46,7 +46,7 @@ func main() {
 	if !*analyzeOnly {
 		fmt.Printf("Preparing new document to write at %s\n", *fileLocation)
 
-		w = docx.New().WithDefaultTheme()
+		w = docx.New().WithDefaultTheme().WithA4Page()
 		// add new paragraph
 		para1 := w.AddParagraph().Justification("distribute")
 		r, err := para1.AddAnchorDrawingFrom("testdata/fumiama.JPG")
@@ -254,7 +254,7 @@ func main() {
 		if err != nil {
 			panic(err)
 		}
-		newFile := docx.New().WithDefaultTheme()
+		newFile := docx.New().WithDefaultTheme().WithA4Page()
 		for i := 0; i < int(*dupnum); i++ {
 			newFile.AppendFile(doc)
 		}
diff --git a/pack.go b/pack.go
index 1927976..b864691 100644
--- a/pack.go
+++ b/pack.go
@@ -36,7 +36,7 @@ func (f *Docx) pack(zipWriter *zip.Writer) (err error) {
 
 	if f.template != "" {
 		for _, name := range f.tmpfslst {
-			files[name], err = TemplateXMLFS.Open("xml/" + f.template + "/" + name)
+			files[name], err = f.tmplfs.Open("xml/" + f.template + "/" + name)
 			if err != nil {
 				return
 			}
diff --git a/structdoc.go b/structdoc.go
index 91cc0a5..4265fa4 100644
--- a/structdoc.go
+++ b/structdoc.go
@@ -90,6 +90,13 @@ func (b *Body) UnmarshalXML(d *xml.Decoder, _ xml.StartElement) error {
 					return err
 				}
 				b.Items = append(b.Items, &value)
+			case "sectPr":
+				var value SectPr
+				err = d.DecodeElement(&value, &tt)
+				if err != nil && !strings.HasPrefix(err.Error(), "expected") {
+					return err
+				}
+				b.Items = append(b.Items, &value)
 			default:
 				err = d.Skip() // skip unsupported tags
 				if err != nil {
diff --git a/structdoc_test.go b/structdoc_test.go
index fa1a840..f1eb2e8 100644
--- a/structdoc_test.go
+++ b/structdoc_test.go
@@ -33,8 +33,8 @@ func TestUnmarshalPlainStructure(t *testing.T) {
 		content       string
 		numParagraphs int
 	}{
-		{decoded_doc_1, 5},
-		{decoded_doc_2, 14},
+		{decoded_doc_1, 6},
+		{decoded_doc_2, 15},
 	}
 	for _, tc := range testCases {
 		doc := Document{
@@ -50,16 +50,22 @@ func TestUnmarshalPlainStructure(t *testing.T) {
 			t.Fatalf("We expected %d paragraphs, we got %d", tc.numParagraphs, len(doc.Body.Items))
 		}
 		for i, it := range doc.Body.Items {
-			p := it.(*Paragraph)
-			if len(p.Children) == 0 {
-				t.Fatalf("We were not able to parse paragraph %d", i)
-			}
-			for _, child := range p.Children {
-				if child == nil {
-					t.Fatalf("There are Paragraph children with all fields nil")
+			switch v := it.(type) {
+			case *Paragraph:
+				if len(v.Children) == 0 {
+					t.Fatalf("We were not able to parse paragraph %d", i)
 				}
-				if o, ok := child.(*Hyperlink); ok && o.ID == "" {
-					t.Fatalf("We have a link without ID")
+				for _, child := range v.Children {
+					if child == nil {
+						t.Fatalf("There are Paragraph children with all fields nil")
+					}
+					if o, ok := child.(*Hyperlink); ok && o.ID == "" {
+						t.Fatalf("We have a link without ID")
+					}
+				}
+			case *SectPr:
+				if v.PgSz.W.Value != "11906" || v.PgSz.H.Value != "16838" {
+					t.Fatalf("We were not able to parse sectPr")
 				}
 			}
 		}
diff --git a/structsect.go b/structsect.go
new file mode 100644
index 0000000..f200cd3
--- /dev/null
+++ b/structsect.go
@@ -0,0 +1,85 @@
+/*
+   Copyright (c) 2024 mabiao0525 (马飚)
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published
+   by the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+package docx
+
+import (
+	"encoding/xml"
+	"io"
+	"strings"
+)
+
+// SectPr show the properties of the document, like paper size
+type SectPr struct {
+	XMLName xml.Name `xml:"w:sectPr,omitempty"` // properties of the document, including paper size
+	PgSz    *PgSz    `xml:"w:pgSz,omitempty"`
+}
+
+// PgSz show the paper size
+type PgSz struct {
+	W xml.Attr `xml:"w:w,attr"` // width of paper
+	H xml.Attr `xml:"w:h,attr"` // high of paper
+}
+
+// UnmarshalXML ...
+func (sect *SectPr) UnmarshalXML(d *xml.Decoder, _ xml.StartElement) error {
+	for {
+		t, err := d.Token()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return err
+		}
+		if tt, ok := t.(xml.StartElement); ok {
+			switch tt.Name.Local {
+			case "pgSz":
+				var value PgSz
+				err = d.DecodeElement(&value, &tt)
+				if err != nil && !strings.HasPrefix(err.Error(), "expected") {
+					return err
+				}
+				sect.PgSz = &value
+			default:
+				err = d.Skip() // skip unsupported tags
+				if err != nil {
+					return err
+				}
+			}
+		}
+	}
+	return nil
+}
+
+// UnmarshalXML ...
+func (pgsz *PgSz) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+	var err error
+
+	for _, attr := range start.Attr {
+		switch attr.Name.Local {
+		case "w":
+			pgsz.W = xml.Attr{Name: xml.Name{Local: "w:w"}, Value: attr.Value}
+		case "h":
+			pgsz.H = xml.Attr{Name: xml.Name{Local: "w:w"}, Value: attr.Value}
+		default:
+			//ignore other attributes now
+		}
+	}
+	// Consume the end element
+	_, err = d.Token()
+	return err
+}
diff --git a/theme.go b/theme.go
index 6748b49..000c0a9 100644
--- a/theme.go
+++ b/theme.go
@@ -20,7 +20,10 @@
 
 package docx
 
-import "io/fs"
+import (
+	"encoding/xml"
+	"io/fs"
+)
 
 // UseTemplate will replace template files
 func (f *Docx) UseTemplate(template string, tmpfslst []string, tmplfs fs.FS) *Docx {
@@ -34,3 +37,27 @@ func (f *Docx) UseTemplate(template string, tmpfslst []string, tmplfs fs.FS) *Do
 func (f *Docx) WithDefaultTheme() *Docx {
 	return f.UseTemplate("default", DefaultTemplateFilesList, TemplateXMLFS)
 }
+
+// WithA3Page use A3 PageSize
+func (f *Docx) WithA3Page() *Docx {
+	sectpr := &SectPr{
+		PgSz: &PgSz{
+			W: xml.Attr{Name: xml.Name{Local: "w:w"}, Value: "16838"},
+			H: xml.Attr{Name: xml.Name{Local: "w:h"}, Value: "23811"},
+		},
+	}
+	f.Document.Body.Items = append(f.Document.Body.Items, sectpr)
+	return f
+}
+
+// WithA4Page use A4 PageSize
+func (f *Docx) WithA4Page() *Docx {
+	sectpr := &SectPr{
+		PgSz: &PgSz{
+			W: xml.Attr{Name: xml.Name{Local: "w:w"}, Value: "11906"},
+			H: xml.Attr{Name: xml.Name{Local: "w:h"}, Value: "16838"},
+		},
+	}
+	f.Document.Body.Items = append(f.Document.Body.Items, sectpr)
+	return f
+}