tell application "Safari"
if (exists of document 1) is false then make new document
set screenAvailableWidth to (do JavaScript "screen.availWidth" in document 1)
set screenAvailableHeight to (do JavaScript "screen.availHeight" in document 1)
set screenWidth to (do JavaScript "screen.width" in document 1)
set screenHeight to (do JavaScript "screen.height" in document 1)
set dockWidth to screenWidth - screenAvailableWidth
set menuBarHeight to screenHeight - screenAvailableHeight
set bounds of window 1 to {dockWidth + 1, menuBarHeight + 1, screenWidth, screenHeight}
-- set bounds of window 1 to {dockWidth + 1, menuBarHeight + 1, screenWidth, screenHeight / 2}
end tell
NOTE: JavaScript execution in the Safari settings must be allowed by you.