fix(style): fix paragraph spacing formula, reduce from 2x to linear extra lines

src/style.rs

@@ -40,7 +40,7 @@ impl StyleProfile {
                 name: "宽松".into(),
                 alignment: TextAlignment::Left,
                 line_spacing: 1.0,
-                paragraph_spacing: 3.0,
+                paragraph_spacing: 1.0,
                 first_line_indent: 2.0,
                 font_size: 26.0,
             },
@@ -70,9 +70,9 @@ fn apply_para_spacing(text: &str, spacing: f32) -> String {
     if spacing <= 0.0 {
         return text.to_string();
     }
-    // Each unit of spacing adds one empty line between paragraphs
-    let extra_nls = (spacing * 2.0).round() as usize + 2; // minimum 2 newlines (1 empty line)
-    let sep = "\n".repeat(extra_nls);
+    // spacing 表示额外空白行数：基础换行 \n\n 已有1行空白，再加 spacing 行
+    let newlines = 2 + spacing.round().max(0.0) as usize;
+    let sep = "\n".repeat(newlines);
     text.replace("\n\n", &sep)
 }