Both Windows 10 and 8 have a hidden Aero Lite theme. You can easily activate that theme in either platform with WinAero Tweaker. By activating that theme, you can then also adjust the width of window borders in Windows 10 with the same software.
First, you’ll need to add WinAero Tweaker to Windows 10 from this page. Click Download WinAero Tweaker on that page to save its Zip folder. You can extract the Zip folder in File Explorer by selecting the Extract all option. Run WinAero Tweaker from the extracted folder to open its window.
First, activate the Aero Lite theme to customize the Windows 10 window borders with the software. Click Aero Lite to open the options shown in the shot below. You can select to switch to an Aero Light theme with black or white text.
Now select Enable Aero Light (Default) from there. That will switch the theme to Aero Light as in the shot below. The WinAero window will have a light blue title bar, and it effectively removes the plain title bars from Windows 10.
Next, select Window Borders on the left of the WinAero window to open the options shown below. As stated there, this option doesn’t work with the default Windows 10 theme. Drag the Border width and padding bars further right to expand the window frame.
Then click the Apply changes button to adjust the window frame as shown in the shot below. Dragging the bars largely expands or reduces the title bar width, and to a lesser extent they also adjust the rest of the border. In addition, the bars also expand or reduce the buttons on the window title bars.
So with WinAero Tweaker you can now add the AeroLite theme to Windows 10 and adjust the window border width. This software also has other options that you can customize the window title bar height and font with.