When you export your in5 content with Back/Next Arrows, you can modify their appearance by adding CSS to the Resources section of the Export HTML5 with in5 dialog (either in5 in5 > Export HTML5 with in5... or to in5 > Easy Export Wizard... and click the Advanced button). 

Use any of the following, combine them, or customize them as needed.

Change the position of the Back/Next Arrows:

nav#page-nav > button {

Modify the position by changing the percentage (e.g. 10% is near the top, and 90% is near the bottom).

Scale the Back/Next Arrows:

nav#page-nav > button {

Change the values to change the size of the Back/Next arrows.

Apply a blend mode:

nav#page-nav > button {
    mix-blend-mode: multiply;

Set the blend mode* to any of the following:

  • multiply
  • screen
  • overlay
  • darken
  • lighten
  • color-dodge
  • color-burn
  • difference
  • exclusion
  • hue
  • saturation
  • color
  • luminosity

   *Check https://caniuse.com/css-backgroundblendmode for browser support.

Apply a filter to invert them:

nav#page-nav > button {
    filter: invert(1);

Change the amount of inversion by setting the value inside the parentheses (0 is no inversion, 1 is fully inverted, .5 or 50% is halfway).