Correct

字里行间

/ zì lǐ hángjiān / 
Strokes

Definition

between the words and the lines (idiom); implied meaning/connotations

Example

Definition

between the lines

1
Tā
他
de
的
wénzhāng
文章
zìlǐhángjiān
字里行间
chōngmǎn
充满
le
了
lèguān
乐观
zhǔyì
主义
jīngshén
精神
  
。

By reading between the lines, you'll find that his article is permeated with optimism.