[Description] The "x" button overlaps the Email account when entering massive characters in FireFox account sign in page. [Test Steps] 1. Launch Browser. 2. Click Menu icon and click "Sign in to Sync". 3. Enter massive characters in Email field. 4. The "x" button overlaps the Email account. [Expected Result] 4. The "x" button should NOT overlap the Email account. [Actual Result] 4. The "x" button overlaps the Email account. [Frequency] 5/5 [Build Info] Environment: 2.6 Simulator gaia:https://github.com/mozilla-b2g/gaia/commit/f0a03a0d46696baf2b7075e1bf5e0afcc55fa8ab gecko:https://hg.mozilla.org/mozilla-central/rev/b2a3dc4b161fdfac6db78cc5bbfb1f53a383b65a This issue can be reproduced on v2.5 [Build Info] Environment: 2.5 Simulator gaia: https://github.com/mozilla-b2g/gaia/commit/2caf834f638eaeb442e536d811bd161a6414ebcb gecko: https://hg.mozilla.org/releases/mozilla-b2g44_v2_5/rev/c6ad35a70c45df5f74fe31eaf8e69b4c1851db5e mulet: https://hg.mozilla.org/releases/mozilla-b2g44_v2_5/rev/c6ad35a70c45df5f74fe31eaf8e69b4c1851db5e [TCID] 16878