properly omit negative for values that round to zero

src/value/number.rs

@@ -165,10 +165,6 @@ from_integer!(u8);
 
 impl Display for Number {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        if self.val.is_negative() {
-            f.write_char('-')?;
-        }
-
         let mut whole = self.val.to_integer().abs();
         let mut dec = String::new();
 
@@ -218,6 +214,10 @@ impl Display for Number {
                 }
             }
         }
+
+        if self.val.is_negative() && (!whole.is_zero() || !dec.is_empty()) {
+            f.write_char('-')?;
+        }
         write!(f, "{}", whole)?;
         write!(f, "{}", dec)?;
         Ok(())

tests/number.rs

@@ -81,3 +81,8 @@ test!(
     "a {\n  color: 1 + 3/4;\n}\n",
     "a {\n  color: 1.75;\n}\n"
 );
+test!(
+    negative_near_zero_no_sign,
+    "a {\n  color: -0.000000000001;\n}\n",
+    "a {\n  color: 0;\n}\n"
+);