How can I change the widht of an SplitPane

Hi everybody, how can I change the widht of an ion-pane, make it narrow.

<ion-split-pane when="lg">
<ion-menu [content]="content" >
  <ion-content class="BGMENU">

      <img src="assets/imgs/AgnicoEagleBlack.png" class="logoMenu">
      <button menuClose *ngFor="let p of pages" (click)="openPage(p)">
<ion-nav [root]="rootPage" main #content swipeBackEnabled="false" ></ion-nav>

I try updateing the value of $split-pane-wp-side-max-width in my theme/varables.scss but nothing changes

// App Windows Variables
// --------------------------------------------------
// Windows only Sass variables can go here
$split-pane-wp-side-max-width: 0%;

// App Theme
// --------------------------------------------------
// Ionic apps can have different themes applied, which can
// then be future customized. This import comes last
// so that the above variables are used and Ionic's
// default are overridden.

@import "ionic.theme.default";