Display: Inline block – What is that space? [duplicate]

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Inline Blocks have this weird space in-between them. I could live with it, up to a point where, if I load more content with an AJAX Call, the tiny space goes away. I know I’m missing something here.

div {
    width: 100px;
    height: auto;
    border: 1px solid red;
    outline: 1px solid blue;
    margin: 0;
    padding: 0; 
    display: inline-block;


How to make the spacing consistent in Inline blocks ?