#### green box

position: relative; width: 40px; height: 40px; padding: 5px; border: 5px solid blue;

#### black box

position: as specified individually; width: 50%; height: 100%; right: 0; bottom: 0; padding: 0; border: none;

box-sizing | position | should be | actual rendering
--- | --- | --- | ---
content-box | static |  |
relative |  |
absolute |  |
border-box | static |  |
relative |  |
absolute |  |