fix: Switch dimmed to font-weight: lighter

This is what the wikipedia article says a terminal *might* do.

Author: epage

crates/anstyle-svg/src/lib.rs

@@ -414,7 +414,7 @@ fn write_effects_in_use(buffer: &mut String, elements: &[adapter::Element]) {
         .unwrap();
     }
     if effects_in_use.contains(anstyle::Effects::DIMMED) {
-        writeln!(buffer, r#"    .dimmed {{ opacity: 0.7; }}"#).unwrap();
+        writeln!(buffer, r#"    .dimmed {{ font-weight: 100; }}"#).unwrap();
     }
     if effects_in_use.contains(anstyle::Effects::HIDDEN) {
         writeln!(buffer, r#"    .hidden {{ opacity: 0; }}"#).unwrap();

crates/anstyle-svg/tests/rainbow.html

@@ -786,7 +786,7 @@
     .dotted-underline { text-decoration-line: underline; text-decoration-style: dotted; }
     .dashed-underline { text-decoration-line: underline; text-decoration-style: dashed; }
     .strikethrough { text-decoration-line: line-through; }
-    .dimmed { opacity: 0.7; }
+    .dimmed { font-weight: 200; }
     .hidden { opacity: 0; }
     span {
       font: 14px SFMono-Regular, Consolas, Liberation Mono, Menlo, monospace;