diff --git a/src/clean-ast.js b/src/clean-ast.js
index 44419e66d..8608b46bc 100644
--- a/src/clean-ast.js
+++ b/src/clean-ast.js
@@ -88,7 +88,6 @@ function massageAST(ast, parent) {
       (ast.type === "value-word" && ast.isColor && ast.isHex) ||
       ast.type === "media-feature" ||
       ast.type === "selector-root-invalid" ||
-      ast.type === "selector-tag" ||
       ast.type === "selector-pseudo"
     ) {
       newObj.value = newObj.value.toLowerCase();
@@ -99,9 +98,6 @@ function massageAST(ast, parent) {
     if (ast.type === "css-atrule" || ast.type === "css-import") {
       newObj.name = newObj.name.toLowerCase();
     }
-    if (ast.type === "selector-attribute") {
-      newObj.attribute = newObj.attribute.toLowerCase();
-    }
     if (ast.type === "value-number") {
       newObj.unit = newObj.unit.toLowerCase();
     }
@@ -139,7 +135,8 @@ function massageAST(ast, parent) {
         ast.type === "value-number" ||
         ast.type === "selector-root-invalid" ||
         ast.type === "selector-class" ||
-        ast.type === "selector-combinator") &&
+        ast.type === "selector-combinator" ||
+        ast.type === "selector-tag") &&
       newObj.value
     ) {
       newObj.value = newObj.value.replace(
diff --git a/src/printer-postcss.js b/src/printer-postcss.js
index f29b5e362..e5e7ffa70 100644
--- a/src/printer-postcss.js
+++ b/src/printer-postcss.js
@@ -222,12 +222,7 @@ function genericPrint(path, options, print) {
       return adjustStrings(n.value, options);
     }
     case "selector-tag": {
-      const parent = path.getParentNode();
-      const index = parent.nodes.indexOf(n);
-      const previous = index > 0 ? parent.nodes[index - 1] : null;
-      return previous && previous.type === "selector-nesting"
-        ? n.value
-        : maybeToLowerCase(n.value);
+      return adjustNumbers(n.value);
     }
     case "selector-id": {
       return concat(["#", n.value]);
@@ -238,7 +233,7 @@ function genericPrint(path, options, print) {
     case "selector-attribute": {
       return concat([
         "[",
-        maybeToLowerCase(n.attribute),
+        n.attribute,
         n.operator ? n.operator : "",
         n.value
           ? quoteAttributeValue(adjustStrings(n.value, options), options)
diff --git a/tests/css_case/__snapshots__/jsfmt.spec.js.snap b/tests/css_case/__snapshots__/jsfmt.spec.js.snap
index b6fcf6840..4435c4858 100644
--- a/tests/css_case/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/css_case/__snapshots__/jsfmt.spec.js.snap
@@ -3,7 +3,8 @@
 exports[`case.less 1`] = `
 // Convention in this test file:
 // - The case should be preserved for things prefixed with "Keep".
-// - The case should always be preserved for function names and property keywords.
+// - The case should always be preserved for element names and attribute names
+//   in selectors, as well as function names and property keywords.
 // - Other things should mostly be lowercase.
 // - The \`/*:*/\` comments are just to bust the \`isLikelySCSS\` check.
 
@@ -11,6 +12,7 @@ exports[`case.less 1`] = `
 
 HTML#KeepId.KeepClass,
 a[HREF=KeepAttrValue]:HOVER::FIRST-letter,
+svg[viewBox] linearGradient,
 :Not(:NTH-child(2N+1)) {
     COLOR: #AAbbCC;
     BACKGROUND-image: URL("KeepString");
@@ -49,7 +51,7 @@ a[HREF=KeepAttrValue]:HOVER::FIRST-letter,
 @KeepTopLevelVar: val;
 $KeepScssVar: val;
 
-.Keep(@Keep: 12e03PX) WHEN (@Keep=Case) /*:*/ {
+.Keep(@Keep: 12e03PX) when (@Keep=Case) /*:*/ {
     @KeepVar: KeepName; /*:*/
     @{KeepInterpolationVar}: val;
     $KeepScssVar: val;
@@ -59,7 +61,7 @@ $KeepScssVar: val;
       prop: val;
     }
 
-    &Keep & NoKeep {
+    &Keep & Element {
       prop: val;
     }
 
@@ -71,14 +73,14 @@ $KeepScssVar: val;
     .Keep;
     .Keep();
     .Keep(4PX)!IMPORTANT;
-    .Keep() WHEN (@Keep=Keep);
-    .Keep() WHEN (@Keep=12PX);
-    .Keep() WHEN (@Keep=Keep12PX);
+    .Keep() when (@Keep=Keep);
+    .Keep() when (@Keep=12PX);
+    .Keep() when (@Keep=Keep12PX);
 }
 
-.Keep (@Keep) WHEN (lightness(@Keep) >= 12PX) AND (@Keep > 0) {}
-.Keep (@Keep) WHEN (lightness(@Keep) != '12PX') AND (@Keep != "12PX") {}
-.Keep (@Keep) WHEN (lightness(@Keep) >= Keep12PX) AND (@Keep > @Keep12E5) {}
+.Keep (@Keep) when (lightness(@Keep) >= 12PX) and (@Keep > 0) {}
+.Keep (@Keep) when (lightness(@Keep) != '12PX') and (@Keep != "12PX") {}
+.Keep (@Keep) when (lightness(@Keep) >= Keep12PX) and (@Keep > @Keep12E5) {}
 
 .Keep(@Keep: 12PX; @Keep: @Keep12PX; ...) /*:*/ {}
 .Keep(@Keep: '12PX'; @Keep: "12PX"; ...) /*:*/ {}
@@ -89,14 +91,16 @@ $KeepScssVar: val;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 // Convention in this test file:
 // - The case should be preserved for things prefixed with "Keep".
-// - The case should always be preserved for function names and property keywords.
+// - The case should always be preserved for element names and attribute names
+//   in selectors, as well as function names and property keywords.
 // - Other things should mostly be lowercase.
 // - The \`/*:*/\` comments are just to bust the \`isLikelySCSS\` check.
 
 @import Keep;
 
-html#KeepId.KeepClass,
-a[href="KeepAttrValue"]:hover::first-letter,
+HTML#KeepId.KeepClass,
+a[HREF="KeepAttrValue"]:hover::first-letter,
+svg[viewBox] linearGradient,
 :not(:nth-child(2n + 1)) {
   color: #aabbcc;
   background-image: URL("KeepString");
@@ -108,7 +112,7 @@ a[href="KeepAttrValue"]:hover::first-letter,
 }
 
 @keyframes KeepAnimationName {
-  from {
+  FROM {
     prop: val;
   }
 
@@ -116,7 +120,7 @@ a[href="KeepAttrValue"]:hover::first-letter,
     prop: val;
   }
 
-  to {
+  TO {
     prop: val;
   }
 }
@@ -146,7 +150,7 @@ $KeepScssVar: val;
     prop: val;
   }
 
-  &Keep & nokeep {
+  &Keep & Element {
     prop: val;
   }
 
@@ -186,13 +190,15 @@ $KeepScssVar: val;
 exports[`case.scss 1`] = `
 // Convention in this test file:
 // - The case should be preserved for things prefixed with "Keep".
-// - The case should always be preserved for function names and property keywords.
+// - The case should always be preserved for element names and attribute names
+//   in selectors, as well as function names and property keywords.
 // - Other things should mostly be lowercase.
 
 @IMPORT Keep;
 
 HTML#KeepId.KeepClass,
 a[HREF=KeepAttrValue]:HOVER::FIRST-letter,
+svg[viewBox] linearGradient,
 :Not(:NTH-child(2N+1)) {
     COLOR: #AAbbCC;
     BACKGROUND-image: URL("KeepString");
@@ -209,7 +215,7 @@ a[HREF=KeepAttrValue]:HOVER::FIRST-letter,
   }
 
   #{$KeepInterpolationVar},
-  #{$Keep + 15PX},
+  #{$Keep + 15PX + Keep15PX + '15PX' + "15PX"},
   #{$Keep + $Keep15PX} {
     prop: val;
   }
@@ -245,7 +251,7 @@ $KeepTopLevelVar: val;
       prop: val;
     }
 
-    &Keep & NoKeep {
+    &Keep & Element {
       prop: val;
     }
 
@@ -274,13 +280,15 @@ $KeepTopLevelVar: val;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 // Convention in this test file:
 // - The case should be preserved for things prefixed with "Keep".
-// - The case should always be preserved for function names and property keywords.
+// - The case should always be preserved for element names and attribute names
+//   in selectors, as well as function names and property keywords.
 // - Other things should mostly be lowercase.
 
 @import Keep;
 
-html#KeepId.KeepClass,
-a[href="KeepAttrValue"]:hover::first-letter,
+HTML#KeepId.KeepClass,
+a[HREF="KeepAttrValue"]:hover::first-letter,
+svg[viewBox] linearGradient,
 :not(:nth-child(2n + 1)) {
   color: #aabbcc;
   background-image: URL("KeepString");
@@ -292,17 +300,17 @@ a[href="KeepAttrValue"]:hover::first-letter,
 }
 
 @keyframes KeepAnimationName {
-  from {
+  FROM {
     prop: val;
   }
 
   #{$KeepInterpolationVar},
-  #{$Keep + 15px},
+  #{$Keep + 15px + Keep15PX + "15PX" + "15PX"},
   #{$Keep + $Keep15PX} {
     prop: val;
   }
 
-  to {
+  TO {
     prop: val;
   }
 }
@@ -334,7 +342,7 @@ $KeepTopLevelVar: val;
     prop: val;
   }
 
-  &Keep & nokeep {
+  &Keep & Element {
     prop: val;
   }
 
diff --git a/tests/css_case/case.less b/tests/css_case/case.less
index 0cf139860..28ccd5ce8 100644
--- a/tests/css_case/case.less
+++ b/tests/css_case/case.less
@@ -1,6 +1,7 @@
 // Convention in this test file:
 // - The case should be preserved for things prefixed with "Keep".
-// - The case should always be preserved for function names and property keywords.
+// - The case should always be preserved for element names and attribute names
+//   in selectors, as well as function names and property keywords.
 // - Other things should mostly be lowercase.
 // - The `/*:*/` comments are just to bust the `isLikelySCSS` check.
 
@@ -8,6 +9,7 @@
 
 HTML#KeepId.KeepClass,
 a[HREF=KeepAttrValue]:HOVER::FIRST-letter,
+svg[viewBox] linearGradient,
 :Not(:NTH-child(2N+1)) {
     COLOR: #AAbbCC;
     BACKGROUND-image: URL("KeepString");
@@ -46,7 +48,7 @@ a[HREF=KeepAttrValue]:HOVER::FIRST-letter,
 @KeepTopLevelVar: val;
 $KeepScssVar: val;
 
-.Keep(@Keep: 12e03PX) WHEN (@Keep=Case) /*:*/ {
+.Keep(@Keep: 12e03PX) when (@Keep=Case) /*:*/ {
     @KeepVar: KeepName; /*:*/
     @{KeepInterpolationVar}: val;
     $KeepScssVar: val;
@@ -56,7 +58,7 @@ $KeepScssVar: val;
       prop: val;
     }
 
-    &Keep & NoKeep {
+    &Keep & Element {
       prop: val;
     }
 
@@ -68,14 +70,14 @@ $KeepScssVar: val;
     .Keep;
     .Keep();
     .Keep(4PX)!IMPORTANT;
-    .Keep() WHEN (@Keep=Keep);
-    .Keep() WHEN (@Keep=12PX);
-    .Keep() WHEN (@Keep=Keep12PX);
+    .Keep() when (@Keep=Keep);
+    .Keep() when (@Keep=12PX);
+    .Keep() when (@Keep=Keep12PX);
 }
 
-.Keep (@Keep) WHEN (lightness(@Keep) >= 12PX) AND (@Keep > 0) {}
-.Keep (@Keep) WHEN (lightness(@Keep) != '12PX') AND (@Keep != "12PX") {}
-.Keep (@Keep) WHEN (lightness(@Keep) >= Keep12PX) AND (@Keep > @Keep12E5) {}
+.Keep (@Keep) when (lightness(@Keep) >= 12PX) and (@Keep > 0) {}
+.Keep (@Keep) when (lightness(@Keep) != '12PX') and (@Keep != "12PX") {}
+.Keep (@Keep) when (lightness(@Keep) >= Keep12PX) and (@Keep > @Keep12E5) {}
 
 .Keep(@Keep: 12PX; @Keep: @Keep12PX; ...) /*:*/ {}
 .Keep(@Keep: '12PX'; @Keep: "12PX"; ...) /*:*/ {}
diff --git a/tests/css_case/case.scss b/tests/css_case/case.scss
index 3cfa0915c..ea8a7733f 100644
--- a/tests/css_case/case.scss
+++ b/tests/css_case/case.scss
@@ -1,12 +1,14 @@
 // Convention in this test file:
 // - The case should be preserved for things prefixed with "Keep".
-// - The case should always be preserved for function names and property keywords.
+// - The case should always be preserved for element names and attribute names
+//   in selectors, as well as function names and property keywords.
 // - Other things should mostly be lowercase.
 
 @IMPORT Keep;
 
 HTML#KeepId.KeepClass,
 a[HREF=KeepAttrValue]:HOVER::FIRST-letter,
+svg[viewBox] linearGradient,
 :Not(:NTH-child(2N+1)) {
     COLOR: #AAbbCC;
     BACKGROUND-image: URL("KeepString");
@@ -23,7 +25,7 @@ a[HREF=KeepAttrValue]:HOVER::FIRST-letter,
   }
 
   #{$KeepInterpolationVar},
-  #{$Keep + 15PX},
+  #{$Keep + 15PX + Keep15PX + '15PX' + "15PX"},
   #{$Keep + $Keep15PX} {
     prop: val;
   }
@@ -59,7 +61,7 @@ $KeepTopLevelVar: val;
       prop: val;
     }
 
-    &Keep & NoKeep {
+    &Keep & Element {
       prop: val;
     }
 
diff --git a/tests/css_combinator/__snapshots__/jsfmt.spec.js.snap b/tests/css_combinator/__snapshots__/jsfmt.spec.js.snap
index 7597d5a05..8d7826ace 100644
--- a/tests/css_combinator/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/css_combinator/__snapshots__/jsfmt.spec.js.snap
@@ -13,7 +13,7 @@ exports[`combinator.css 1`] = `
 .x
     .y {}
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--option/root .public/section ~ .public/section:before {
+-Option/root .public/section ~ .public/section:before {
 }
 
 .x .y {