add backup warning view to backup flow

src/sass/views/backup-warning.scss

@@ -0,0 +1,54 @@
+#backup-warning{
+  .warning{
+    margin:4rem auto 1rem;
+    height: 11rem;
+  }
+  button{
+    color:#fff;
+  }
+  #arrow-down{
+    font-size: 4.2rem;
+  }
+  .cta-buttons{
+    float:none;
+    bottom:67px;
+    position: absolute;
+    width:100%;
+    button{
+      max-width: 400px;
+    }
+  }
+}
+
+@media (max-width: 400px){
+  #backup-warning{
+    .warning{
+      margin: 2rem auto 1rem;
+      height: 8rem;
+    }
+    h3{
+      font-size:1.3rem;
+    }
+    p{
+      font-size:.9rem;
+      max-width: 80%;
+      flex: 0 0 80%;
+    }
+    .warning-image{
+      height: 11rem;
+    }
+    .cta-buttons{
+      float:none;
+      bottom:65px;
+      position: absolute;
+    }
+  }
+}
+@media (max-height: 540px){
+  #backup-warning{
+    .cta-buttons{
+      float:left;
+      position: relative;
+    }
+  }
+}