The color of Proceed with Public Gateway button on IPFS interstitial page for Light theme is wrong

[btlechowski]

Follow up to #10220, #13544
Makes the text hard to read.

Steps to Reproduce

Based on #13544

1. Clean profile
2. Change to Light Brave colors in brave://settings/appearance
3. Open https://dweb.link/ipfs/bafybeiemxf5abjwjbikoz4mc3a3dla6ual3jsgpdr4cjr3oz3evfyavhwq/wiki/Vincent_van_Gogh.html
4. Enable IPFS from infobar.
5. Open brave://settings/extensions and confirm "Method to resolve IPFS resources" is Local Node and the "IPFS public gateway fallback" switch is off.
6. turn off your network and visit brave://ipfs
7. Stop the node, confirm 0 peers are connected
8. Open ipfs://QmbWqxBEKC3P8tqsKc98xmWNzrzDtRLMiMPL8wBuTGsMnR
9. Get interstitial page

Actual result:

The color is wrong and text is hard to read

Expected result:

Text is easy to read

Reproduces how often:

Easily reproduced

Brave version (brave://version info)

Brave	1.19.84 Chromium: 88.0.4324.87 (Official Build) (64-bit)
Revision	dd01ff8f58c65af81127ad5c105c79d5b571d8f3-refs/branch-heads/4324@{#1702}
OS	Ubuntu 18.04 LTS

Brave	1.20.79 Chromium: 88.0.4324.79 (Official Build) dev (64-bit)
Revision	bd1e9353659b2491dac971226a973ca3b5684a14-refs/branch-heads/4324@{#1520}
OS	Ubuntu 18.04 LTS

Brave	1.21.4 Chromium: 88.0.4324.87 (Official Build) nightly (64-bit)
Revision	dd01ff8f58c65af81127ad5c105c79d5b571d8f3-refs/branch-heads/4324@{#1702}
OS	Ubuntu 18.04 LTS

cc @brave/legacy_qa @bbondy @yrliou

[LaurenWags]

Reproduces on macOS light theme. Dark theme is fine.

Brave | 1.19.84 Chromium: 88.0.4324.87 (Official Build) (x86_64)
-- | --
Revision | dd01ff8f58c65af81127ad5c105c79d5b571d8f3-refs/branch-heads/4324@{#1702}
OS | macOS Version 10.15.7 (Build 19H15)

Light	Dark

[GeetaSarvadnya]

Reproduced on Windows 10 x64 - 1.19.84

[GeetaSarvadnya]

Verification passed on

Brave | 1.19.85 Chromium: 88.0.4324.89 (Official Build) (64-bit)
-- | --
Revision | 4534be84786f5269fb52e9bf82643af61e2fedaf-refs/branch-heads/4324@{#1721}
OS | Windows 10 OS Version 2004 (Build 19041.746)

• Verified the STR from the description
  Light Mode:
  
  

Dark Mode

---

Verification passed on

Brave	1.19.85 Chromium: 88.0.4324.89 (Official Build) (64-bit)
Revision	4534be84786f5269fb52e9bf82643af61e2fedaf-refs/branch-heads/4324@{#1721}
OS	Ubuntu 18.04 LTS

Verified test plan from the description.

Light Brave colors

Dark Brave colors

---

Verification PASSED on macOS 11.1 x64 using the following build:

Brave | 1.19.85 Chromium: 88.0.4324.89 (Official Build) (x86_64)
--- | ---
Revision | 4534be84786f5269fb52e9bf82643af61e2fedaf-refs/branch-heads/4324@{#1721}
OS | macOS Version 11.1 (Build 20C69)

Light	Dark