[Navigation] Change padding-top to space-100 for small viewports (#11403)

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### WHY are these changes introduced?

addresses #10218 <!-- link to
issue if one exists -->

Note: the issue with the arrow cutting off was addressed previously

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  Context about the problem that’s being addressed.
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### WHAT is this pull request doing?

Changing `padding-top` to `space-100` for small viewports

| Before | After |
| -- | -- | 

|![before](https://github.com/Shopify/polaris/assets/20652326/75dabab3-20d7-426d-9553-23d08200f950)|![after](https://github.com/Shopify/polaris/assets/4642404/667a9347-0e40-4bc1-83f8-db0e646a30c4)|

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### How to 🎩

🖥 [Local development
instructions](https://github.com/Shopify/polaris/blob/main/README.md#install-dependencies-and-build-workspaces)
🗒 [General tophatting
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guidelines](https://github.com/Shopify/polaris/blob/main/.github/CONTRIBUTING.md#changelog)

### 🎩 checklist

- [ ] Tested a
[snapshot](https://github.com/Shopify/polaris/blob/main/documentation/Releasing.md#-snapshot-releases)
- [ ] Tested on
[mobile](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting.md#cross-browser-testing)
- [ ] Tested on [multiple
browsers](https://help.shopify.com/en/manual/shopify-admin/supported-browsers)
- [ ] Tested for
[accessibility](https://github.com/Shopify/polaris/blob/main/documentation/Accessibility%20testing.md)
- [ ] Updated the component's `README.md` with documentation changes
- [ ] [Tophatted
documentation](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting%20documentation.md)
changes in the style guide

Author: Yuraima Estevez

.changeset/hip-oranges-joke.md

@@ -0,0 +1,5 @@
+---
+'@shopify/polaris': minor
+---
+
+[Navigation] Updated `padding-top` to `space-100` for small viewports

polaris-react/src/components/Navigation/Navigation.module.scss

@@ -57,14 +57,15 @@ $nav-max-width: 360px;
   flex-direction: column;
   align-items: stretch;
   max-width: 100%;
-
-  &:focus {
-    outline: none;
-  }
+  padding-top: var(--p-space-100);
 
   @media #{$p-breakpoints-md-up} {
     padding-top: var(--p-space-400);
   }
+
+  &:focus {
+    outline: none;
+  }
 }
 
 .LogoContainer {