fix(core): support slidesOffsetBefore and slidesOffsetAfert in cssMode

fixes #7926

Author: nolimits4web

src/core/update/updateSlides.mjs

@@ -69,6 +69,12 @@ export default function updateSlides() {
     setCSSProperty(wrapperEl, '--swiper-centered-offset-after', '');
   }
 
+  // set cssMode offsets
+  if (params.cssMode) {
+    setCSSProperty(wrapperEl, '--swiper-slides-offset-before', `${offsetBefore}px`);
+    setCSSProperty(wrapperEl, '--swiper-slides-offset-after', `${offsetAfter}px`);
+  }
+
   const gridEnabled = params.grid && params.grid.rows > 1 && swiper.grid;
   if (gridEnabled) {
     swiper.grid.initSlides(slides);

src/swiper.css

@@ -103,11 +103,25 @@
     > .swiper-wrapper {
       scroll-snap-type: x mandatory;
     }
+    > .swiper-wrapper > .swiper-slide:first-child {
+      margin-inline-start: var(--swiper-slides-offset-before);
+      scroll-margin-inline-start: var(--swiper-slides-offset-before);
+    }
+    > .swiper-wrapper > .swiper-slide:last-child {
+      margin-inline-end: var(--swiper-slides-offset-after);
+    }
   }
   &.swiper-vertical {
     > .swiper-wrapper {
       scroll-snap-type: y mandatory;
     }
+    > .swiper-wrapper > .swiper-slide:first-child {
+      margin-block-start: var(--swiper-slides-offset-before);
+      scroll-margin-block-start: var(--swiper-slides-offset-before);
+    }
+    > .swiper-wrapper > .swiper-slide:last-child {
+      margin-block-end: var(--swiper-slides-offset-after);
+    }
   }
   &.swiper-free-mode {
     > .swiper-wrapper {