diff --git a/experimental/libbox/native_shell_session.go b/experimental/libbox/native_shell_session.go
index 82fec5f3..d9bd5d29 100644
--- a/experimental/libbox/native_shell_session.go
+++ b/experimental/libbox/native_shell_session.go
@@ -25,7 +25,7 @@ func OpenNativeShellSession(
 		cwd,
 		int(uid), int(gid),
 		common.Map(iteratorToArray[int32](groups), func(g int32) int { return int(g) }),
-		uint16(rows), uint16(cols),
+		uint16(rows), uint16(cols), 0, 0,
 	)
 	if err != nil {
 		return nil, err
@@ -58,7 +58,7 @@ func (s *nativeShellSession) MasterFD() int32 {
 }
 
 func (s *nativeShellSession) Resize(rows, cols int32) error {
-	return s.shell.Resize(uint16(rows), uint16(cols))
+	return s.shell.Resize(uint16(rows), uint16(cols), 0, 0)
 }
 
 func (s *nativeShellSession) Signal(sig int32) error {
diff --git a/protocol/tailscale/tailssh/server.go b/protocol/tailscale/tailssh/server.go
index 27dc9d25..476f06b7 100644
--- a/protocol/tailscale/tailssh/server.go
+++ b/protocol/tailscale/tailssh/server.go
@@ -582,11 +582,13 @@ func (s *Server) handleSession(session gliderssh.Session) {
 	session.DisablePTYEmulation()
 	command := session.RawCommand()
 	var term string
-	var rows, cols uint16
+	var rows, cols, widthPixels, heightPixels uint16
 	if isPty {
 		term = ptyReq.Term
 		rows = clampWindowDimension(ptyReq.Window.Height)
 		cols = clampWindowDimension(ptyReq.Window.Width)
+		widthPixels = clampWindowDimension(ptyReq.Window.WidthPixels)
+		heightPixels = clampWindowDimension(ptyReq.Window.HeightPixels)
 	}
 	var rec *recording
 	recorderList, onFailure := recorders(connInfo)
@@ -611,12 +613,14 @@ func (s *Server) handleSession(session gliderssh.Session) {
 		}
 	}
 	shellSession, err := s.backend.OpenSession(shellRequest{
-		User:    localUser,
-		Command: command,
-		Env:     env,
-		Term:    term,
-		Rows:    rows,
-		Cols:    cols,
+		User:         localUser,
+		Command:      command,
+		Env:          env,
+		Term:         term,
+		Rows:         rows,
+		Cols:         cols,
+		WidthPixels:  widthPixels,
+		HeightPixels: heightPixels,
 	})
 	if err != nil {
 		s.logger.Error("failed to open shell session: ", err)
@@ -661,7 +665,12 @@ func (s *Server) handleSession(session gliderssh.Session) {
 			for win := range winCh {
 				shellAccess.Lock()
 				if shellAlive {
-					shellSession.Resize(clampWindowDimension(win.Height), clampWindowDimension(win.Width))
+					shellSession.Resize(
+						clampWindowDimension(win.Height),
+						clampWindowDimension(win.Width),
+						clampWindowDimension(win.WidthPixels),
+						clampWindowDimension(win.HeightPixels),
+					)
 				}
 				shellAccess.Unlock()
 			}
diff --git a/protocol/tailscale/tailssh/session.go b/protocol/tailscale/tailssh/session.go
index c57d8467..9afe45f2 100644
--- a/protocol/tailscale/tailssh/session.go
+++ b/protocol/tailscale/tailssh/session.go
@@ -14,12 +14,14 @@ type shellBackend interface {
 }
 
 type shellRequest struct {
-	User    *adapter.PlatformUser
-	Command string
-	Env     []string
-	Term    string
-	Rows    uint16
-	Cols    uint16
+	User         *adapter.PlatformUser
+	Command      string
+	Env          []string
+	Term         string
+	Rows         uint16
+	Cols         uint16
+	WidthPixels  uint16
+	HeightPixels uint16
 }
 
 type shellSession interface {
@@ -27,7 +29,7 @@ type shellSession interface {
 	// CloseWrite signals EOF on the child's stdin without tearing down the
 	// session, so programs that read stdin to EOF can finish normally.
 	CloseWrite() error
-	Resize(rows, cols uint16) error
+	Resize(rows, cols, widthPixels, heightPixels uint16) error
 	Signal(sig int) error
 	Wait() (exitStatus uint32, err error)
 }
diff --git a/protocol/tailscale/tailssh/session_platform.go b/protocol/tailscale/tailssh/session_platform.go
index 5d5c5b77..b613362c 100644
--- a/protocol/tailscale/tailssh/session_platform.go
+++ b/protocol/tailscale/tailssh/session_platform.go
@@ -25,11 +25,15 @@ func (b *platformShellBackend) OpenSession(request shellRequest) (shellSession,
 		return nil, err
 	}
 	master := os.NewFile(uintptr(dupFd), "pty-master")
-	return &platformShellSession{
+	shellSession := &platformShellSession{
 		session: session,
 		master:  master,
 		isPty:   request.Term != "",
-	}, nil
+	}
+	if shellSession.isPty && (request.WidthPixels > 0 || request.HeightPixels > 0) {
+		_ = SetWinsize(int(master.Fd()), request.Rows, request.Cols, request.WidthPixels, request.HeightPixels)
+	}
+	return shellSession, nil
 }
 
 func (b *platformShellBackend) Close() error {
@@ -61,8 +65,17 @@ func (s *platformShellSession) CloseWrite() error {
 	return syscall.Shutdown(int(s.master.Fd()), syscall.SHUT_WR)
 }
 
-func (s *platformShellSession) Resize(rows, cols uint16) error {
-	return s.session.Resize(int32(rows), int32(cols))
+func (s *platformShellSession) Resize(rows, cols, widthPixels, heightPixels uint16) error {
+	err := s.session.Resize(int32(rows), int32(cols))
+	if err != nil {
+		return err
+	}
+	// The platform interface carries no pixel dimensions; set them directly
+	// on the duplicated pty master.
+	if s.isPty && (widthPixels > 0 || heightPixels > 0) {
+		return SetWinsize(int(s.master.Fd()), rows, cols, widthPixels, heightPixels)
+	}
+	return nil
 }
 
 func (s *platformShellSession) Signal(sig int) error {
diff --git a/protocol/tailscale/tailssh/session_unix.go b/protocol/tailscale/tailssh/session_unix.go
index 7b98f58e..dc9d5be7 100644
--- a/protocol/tailscale/tailssh/session_unix.go
+++ b/protocol/tailscale/tailssh/session_unix.go
@@ -45,7 +45,7 @@ func (b *directShellBackend) OpenSession(request shellRequest) (shellSession, er
 		args = []string{"-" + filepath.Base(shell)}
 	}
 	if request.Term != "" {
-		return OpenPtyShell(shell, args, request.Env, request.User.HomeDir, request.User.Uid, request.User.Gid, request.User.Groups, request.Rows, request.Cols)
+		return OpenPtyShell(shell, args, request.Env, request.User.HomeDir, request.User.Uid, request.User.Gid, request.User.Groups, request.Rows, request.Cols, request.WidthPixels, request.HeightPixels)
 	}
 	return OpenSocketpairShell(shell, args, request.Env, request.User.HomeDir, request.User.Uid, request.User.Gid, request.User.Groups)
 }
diff --git a/protocol/tailscale/tailssh/session_windows.go b/protocol/tailscale/tailssh/session_windows.go
index 0b6db19c..4d07f729 100644
--- a/protocol/tailscale/tailssh/session_windows.go
+++ b/protocol/tailscale/tailssh/session_windows.go
@@ -325,7 +325,7 @@ func (s *conptyShellSession) Write(p []byte) (int, error) {
 	return s.input.Write(p)
 }
 
-func (s *conptyShellSession) Resize(rows, cols uint16) error {
+func (s *conptyShellSession) Resize(rows, cols, _, _ uint16) error {
 	return s.console.Resize(windows.Coord{X: clampConsoleDimension(cols), Y: clampConsoleDimension(rows)})
 }
 
@@ -451,7 +451,7 @@ func (s *pipeShellSession) Write(p []byte) (int, error) {
 	return s.stdin.Write(p)
 }
 
-func (s *pipeShellSession) Resize(_, _ uint16) error {
+func (s *pipeShellSession) Resize(_, _, _, _ uint16) error {
 	return nil
 }
 
diff --git a/protocol/tailscale/tailssh/shell_unix.go b/protocol/tailscale/tailssh/shell_unix.go
index 254786f9..774f2dec 100644
--- a/protocol/tailscale/tailssh/shell_unix.go
+++ b/protocol/tailscale/tailssh/shell_unix.go
@@ -13,8 +13,8 @@ type Shell struct {
 	isPty  bool
 }
 
-func OpenPtyShell(shell string, args, env []string, dir string, uid, gid int, groups []int, rows, cols uint16) (*Shell, error) {
-	master, process, err := StartPtyProcess(shell, args, env, dir, uid, gid, groups, rows, cols)
+func OpenPtyShell(shell string, args, env []string, dir string, uid, gid int, groups []int, rows, cols, widthPixels, heightPixels uint16) (*Shell, error) {
+	master, process, err := StartPtyProcess(shell, args, env, dir, uid, gid, groups, rows, cols, widthPixels, heightPixels)
 	if err != nil {
 		return nil, err
 	}
@@ -52,11 +52,11 @@ func (s *Shell) Write(p []byte) (int, error) {
 	return s.master.Write(p)
 }
 
-func (s *Shell) Resize(rows, cols uint16) error {
+func (s *Shell) Resize(rows, cols, widthPixels, heightPixels uint16) error {
 	if !s.isPty {
 		return nil
 	}
-	return SetWinsize(int(s.master.Fd()), rows, cols)
+	return SetWinsize(int(s.master.Fd()), rows, cols, widthPixels, heightPixels)
 }
 
 func (s *Shell) Signal(sig int) error {
diff --git a/protocol/tailscale/tailssh/subprocess_unix.go b/protocol/tailscale/tailssh/subprocess_unix.go
index 09e6b6bd..6b102975 100644
--- a/protocol/tailscale/tailssh/subprocess_unix.go
+++ b/protocol/tailscale/tailssh/subprocess_unix.go
@@ -14,7 +14,7 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-func StartPtyProcess(shell string, args, env []string, dir string, uid, gid int, groups []int, rows, cols uint16) (*os.File, *os.Process, error) {
+func StartPtyProcess(shell string, args, env []string, dir string, uid, gid int, groups []int, rows, cols, widthPixels, heightPixels uint16) (*os.File, *os.Process, error) {
 	cmd := exec.Command(shell)
 	cmd.Args = args
 	cmd.Dir = dir
@@ -27,7 +27,7 @@ func StartPtyProcess(shell string, args, env []string, dir string, uid, gid int,
 	setCredential(attrs, uid, gid, groups)
 	var size *pty.Winsize
 	if rows > 0 && cols > 0 {
-		size = &pty.Winsize{Rows: rows, Cols: cols}
+		size = &pty.Winsize{Rows: rows, Cols: cols, X: widthPixels, Y: heightPixels}
 	}
 	master, err := pty.StartWithAttrs(cmd, size, attrs)
 	if err != nil {
@@ -94,6 +94,11 @@ func setCredential(attr *syscall.SysProcAttr, uid, gid int, groups []int) {
 	attr.Credential = cred
 }
 
-func SetWinsize(fd int, rows, cols uint16) error {
-	return unix.IoctlSetWinsize(fd, unix.TIOCSWINSZ, &unix.Winsize{Row: rows, Col: cols})
+func SetWinsize(fd int, rows, cols, widthPixels, heightPixels uint16) error {
+	return unix.IoctlSetWinsize(fd, unix.TIOCSWINSZ, &unix.Winsize{
+		Row:    rows,
+		Col:    cols,
+		Xpixel: widthPixels,
+		Ypixel: heightPixels,
+	})
 }