add validations

- If you are using a bare value or modifier that is a number, then we
  make sure that it is a valid multiplier of `0.25`
- If you are using a bare value or modifier that is a percentage, then
  we make sure that it is a valid positive integer.
- If you are using a fraction, then we make sure that both the numerator
  and denominator are positive integers.
- If the bare value resolves to a non-ratio value, and if a modifier is
  used, then we need to make sure that the modifier resolves as well.
  E.g.: `example-1/2.3` this won't resolve to a `ratio` because the
  denominator is invalid. This will resolve to an `integer` or `number`
  for the value of `1`, but then we need to make sure that `2.3` is a
  valid modifier.

packages/tailwindcss/src/index.ts

@@ -26,7 +26,7 @@ import { substituteFunctions } from './css-functions'
 import * as CSS from './css-parser'
 import { buildDesignSystem, type DesignSystem } from './design-system'
 import { Theme, ThemeOptions } from './theme'
-import { inferDataType } from './utils/infer-data-type'
+import { inferDataType, isPositiveInteger, isValidSpacingMultiplier } from './utils/infer-data-type'
 import { segment } from './utils/segment'
 import * as ValueParser from './value-parser'
 import { compoundsForSelectors } from './variants'
@@ -217,6 +217,9 @@ async function parseCss(
             // in order to make the utility valid.
             let resolvedValueFn = false
 
+            // The resolved value type, e.g.: `integer`
+            let resolvedValueType = null as string | null
+
             // Whether `modifier(…)` was used
             let usedModifierFn = false
 
@@ -277,6 +280,27 @@ async function parseCss(
 
                         let type = inferDataType(value, [arg.value as any])
                         if (type !== null) {
+                          // Ratio must be a valid fraction, e.g.: <integer>/<integer>
+                          if (type === 'ratio') {
+                            let [lhs, rhs] = segment(value, '/')
+                            if (!isPositiveInteger(lhs) || !isPositiveInteger(rhs)) continue
+                          }
+
+                          // Non-integer numbers should be a valid multiplier,
+                          // e.g.: `1.5`
+                          else if (type === 'number' && !isValidSpacingMultiplier(value)) {
+                            continue
+                          }
+
+                          // Percentages must be an integer, e.g.: `50%`
+                          else if (
+                            type === 'percentage' &&
+                            !isPositiveInteger(value.slice(0, -1))
+                          ) {
+                            continue
+                          }
+
+                          resolvedValueType = type
                           resolvedValueFn = true
                           replaceWith(ValueParser.parse(value))
                           return ValueParser.ValueWalkAction.Skip
@@ -379,6 +403,20 @@ async function parseCss(
                         let value = candidate.modifier.value
                         let type = inferDataType(value, [arg.value as any])
                         if (type !== null) {
+                          // Non-integer numbers should be a valid multiplier,
+                          // e.g.: `1.5`
+                          if (type === 'number' && !isValidSpacingMultiplier(value)) {
+                            continue
+                          }
+
+                          // Percentages must be an integer, e.g.: `50%`
+                          else if (
+                            type === 'percentage' &&
+                            !isPositiveInteger(value.slice(0, -1))
+                          ) {
+                            continue
+                          }
+
                           resolvedModifierFn = true
                           replaceWith(ValueParser.parse(value))
                           return ValueParser.ValueWalkAction.Skip
@@ -424,6 +462,23 @@ async function parseCss(
               }
             })
 
+            // Ensure that the modifier was resolved if present on the
+            // candidate. We also have to make sure that the value is _not_
+            // using a fraction.
+            //
+            // E.g.:
+            //
+            // - `w-1/2`, can be a value of `1` and modifier of `2`
+            // - `w-1/2`, can be a fraction of `1/2` and no modifier
+            if (
+              candidate.value.kind === 'named' &&
+              resolvedValueType !== 'ratio' &&
+              !usedModifierFn &&
+              candidate.modifier !== null
+            ) {
+              return null
+            }
+
             if (usedValueFn && !resolvedValueFn) return null
             if (usedModifierFn && !resolvedModifierFn) return null
 

packages/tailwindcss/src/utilities.test.ts

@@ -17514,6 +17514,47 @@ describe('custom utilities', () => {
       expect(await compileCss(input, ['tab-foo'])).toEqual('')
     })
 
+    test('resolving bare values with constraints for integer, percentage, and ratio', async () => {
+      let input = css`
+        @utility example-* {
+          --value-as-number: value(number);
+          --value-as-percentage: value(percentage);
+          --value-as-ratio: value(ratio);
+        }
+
+        @tailwind utilities;
+      `
+
+      expect(await compileCss(input, ['example-1', 'example-0.5', 'example-20%', 'example-2/3']))
+        .toMatchInlineSnapshot(`
+        ".example-0\\.5 {
+          --value-as-number: .5;
+        }
+
+        .example-1 {
+          --value-as-number: 1;
+        }
+
+        .example-2\\/3 {
+          --value-as-number: 2;
+          --value-as-ratio: 2 / 3;
+        }
+
+        .example-20\\% {
+          --value-as-percentage: 20%;
+        }"
+      `)
+      expect(
+        await compileCss(input, [
+          'example-1.23',
+          'example-12.34%',
+          'example-1.2/3',
+          'example-1/2.3',
+          'example-1.2/3.4',
+        ]),
+      ).toEqual('')
+    })
+
     test('resolving unsupported bare values', async () => {
       let input = css`
         @utility tab-* {