Target last 1 version with Autoprefixer

_sass/basically-basic/_layout.scss

@@ -64,13 +64,10 @@ main {
 .layout--about {
 
   .entry-wrap {
-    display: -ms-flexbox;
     display: flex;
-    -ms-flex-wrap: wrap;
     flex-wrap: wrap;
 
     @include breakpoint($medium) {
-      -ms-flex-wrap: nowrap;
       flex-wrap: nowrap;
     }
   }
@@ -78,7 +75,6 @@ main {
   .entry-content {
 
     @include breakpoint($medium) {
-      -ms-flex: 1;
       flex: 1;
     }
   }

_sass/basically-basic/_navicons.scss

@@ -62,7 +62,6 @@
     border-radius: $navicon-width;
     background: $navicon-content-bg;
     content: '';
-    // z-index: -1;
   }
 
   &::before { top: (2 * $navicon-height); }
@@ -75,7 +74,6 @@
 }
 
 .open {
-  -ms-transform: scale($navicon-toggled-size);
   transform: scale($navicon-toggled-size);
 
   .navicon::before,
@@ -94,22 +92,17 @@
     }
 
     &::before {
-      -ms-transform: rotate(35deg);
       transform: rotate(35deg);
-      -ms-transform-origin: left top;
       transform-origin: left top;
     }
 
     &::after {
-      -ms-transform: rotate(-35deg);
       transform: rotate(-35deg);
-      -ms-transform-origin: left bottom;
       transform-origin: left bottom;
     }
   }
 
   &.uarr {
-    -ms-transform: scale($navicon-toggled-size) rotate(90deg);
     transform: scale($navicon-toggled-size) rotate(90deg);
   }
 
@@ -117,37 +110,35 @@
 
     &::before {
       transform: translate3d(1em, 0, 0) rotate(-35deg);
-      -ms-transform-origin: right top;
       transform-origin: right top;
     }
 
     &::after {
       transform: translate3d(1em, 0, 0) rotate(35deg);
-      -ms-transform-origin: right bottom;
       transform-origin: right bottom;
     }
   }
 
   /* × and + */
-  // &.plus,
+  /* &.plus,*/
-  // &.x {
+  /* &.x {*/
-  //   .navicon {
+  /*   .navicon {*/
-  //     background: transparent;
+  /*     background: transparent;*/
 
-  //     &::before {
+  /*     &::before {*/
-  //       -ms-transform: rotate(-45deg);
+  /*       -ms-transform: rotate(-45deg);*/
-  //       transform: rotate(-45deg);
+  /*       transform: rotate(-45deg);*/
-  //     }
+  /*     }*/
 
-  //     &::after {
+  /*     &::after {*/
-  //       -ms-transform: rotate(45deg);
+  /*       -ms-transform: rotate(45deg);*/
-  //       transform: rotate(45deg);
+  /*       transform: rotate(45deg);*/
-  //     }
+  /*     }*/
-  //   }
+  /*   }*/
-  // }
+  /* }*/
 
-  // &.plus {
+  /* &.plus {*/
-  //   -ms-transform: scale($navicon-toggled-size) rotate(45deg);
+  /*   -ms-transform: scale($navicon-toggled-size) rotate(45deg);*/
-  //   transform: scale($navicon-toggled-size) rotate(45deg);
+  /*   transform: scale($navicon-toggled-size) rotate(45deg);*/
-  // }
+  /* }*/
 }

_sass/basically-basic/_navigation.scss

@@ -21,11 +21,9 @@
 
   ul {
     @include list-unstyled;
-    display: -ms-flexbox;
     display: flex;
 
     > li {
-      -ms-flex: 1;
       flex: 1;
       justify-content: space-between;
       -ms-flex-pack: justify;

_sass/basically-basic/_sidebar.scss

@@ -29,14 +29,11 @@
   }
 
   li {
-
-    -ms-transform: translateX(-1rem);
     transform: translateX(-1rem);
     transition: all 0.5s;
     opacity: 0;
 
     &.is--moved {
-      -ms-transform: translateX(0);
       transform: translateX(0);
       opacity: 1;
     }
@@ -69,7 +66,6 @@
   }
 
   &.is--visible {
-    -ms-transform: translateX(0);
     transform: translateX(0);
 
     &::after {
@@ -78,7 +74,6 @@
     }
 
     > .inner {
-      -ms-transform: none;
       transform: none;
       box-shadow: 0 1em 5em 0 rgba(0, 0, 0, 0.125);
     }
@@ -98,7 +93,6 @@
     max-width: $sidebar-width;
     height: 100%;
     padding: 1.5em;
-    -ms-transform: translateX(-1 * $sidebar-width);
     transform: translateX(-1 * $sidebar-width);
     background-color: $sidebar-background-color;
     box-shadow: none;
@@ -113,7 +107,6 @@
 
     @include breakpoint($large) {
       max-width: (1.5 * $sidebar-width);
-      -ms-transform: translateX(-1.5 * $sidebar-width);
       transform: translateX(-1.5 * $sidebar-width);
     }
   }
@@ -170,9 +163,7 @@
   z-index: 10000;
 
   .toggle {
-    display: -ms-flexbox;
     display: flex;
-    -ms-flex-align: center;
     align-items: center;
     color: inherit;
     text-decoration: none;
@@ -180,7 +171,6 @@
 }
 
 .sidebar-toggle-label {
-  -ms-flex-order: 2;
   order: 2;
   margin-left: 0.5rem;
   font-weight: bold;

_sass/basically-basic/utilities/_align.scss

@@ -2,7 +2,7 @@
    Alignment
    ========================================================================== */
 
-.align-baseline { vertical-align: baseline !important; } // Browser default
+.align-baseline { vertical-align: baseline !important; } /* Browser default */
 .align-top { vertical-align: top !important; }
 .align-middle { vertical-align: middle !important; }
 .align-bottom { vertical-align: bottom !important; }