diff --git a/stylelint.config.js b/stylelint.config.js
index 87ad25659a..5db04a336b 100644
--- a/stylelint.config.js
+++ b/stylelint.config.js
@@ -26,5 +26,20 @@ module.exports = {
         // Limit language features
         "color-no-hex": true,
         "color-named": "never",
+        "declaration-property-value-blacklist": {
+            // thin/medium/thick is under-specified, please use pixels
+            "/^(border(-top|-right|-bottom|-left)?|outline)(-width)?$/": [
+                /\b(thin|medium|thick)\b/,
+            ],
+        },
+        "function-blacklist": [
+            // We use hsl(a) instead of rgb(a)
+            "rgb",
+            "rgba",
+        ],
+
+        // Zulip CSS should have no dependencies on external resources
+        "function-url-no-scheme-relative": true,
+        "function-url-scheme-whitelist": [],
     },
 };
diff --git a/tools/linter_lib/custom_check.py b/tools/linter_lib/custom_check.py
index 8092e4390c..5fa6fb3e54 100644
--- a/tools/linter_lib/custom_check.py
+++ b/tools/linter_lib/custom_check.py
@@ -418,26 +418,6 @@ bash_rules = RuleList(
 css_rules = RuleList(
     langs=['css', 'scss'],
     rules=[
-        {'pattern': r'^(?:(?!/\*).)*https?://',
-         'description': "Zulip CSS should have no dependencies on external resources",
-         'good_lines': ['background: url(/static/images/landing-page/pycon.jpg);'],
-         'bad_lines': ['background: url(https://example.com/image.png);']},
-        {'pattern': ' thin[ ;]',
-         'description': "thin CSS attribute is under-specified, please use 1px.",
-         'good_lines': ["border-width: 1px;"],
-         'bad_lines': ["border-width: thin;", "border-width: thin solid black;"]},
-        {'pattern': ' medium[ ;]',
-         'description': "medium CSS attribute is under-specified, please use pixels.",
-         'good_lines': ["border-width: 3px;"],
-         'bad_lines': ["border-width: medium;", "border: medium solid black;"]},
-        {'pattern': ' thick[ ;]',
-         'description': "thick CSS attribute is under-specified, please use pixels.",
-         'good_lines': ["border-width: 5px;"],
-         'bad_lines': ["border-width: thick;", "border: thick solid black;"]},
-        {'pattern': r'rgba?\(',
-         'description': 'Use of rgb(a) format is banned, Please use hsl(a) instead',
-         'good_lines': ['hsl(0, 0%, 0%)', 'hsla(0, 0%, 100%, 0.1)'],
-         'bad_lines': ['rgb(0, 0, 0)', 'rgba(255, 255, 255, 0.1)']},
         *whitespace_rules,
     ],
 )