It appears that your design is quite intriguing with a variety of numerical elements in play. The default margin on the body, 5em of padding, and positioning the metal box at 11.8% off these values all contribute to the layout. To ensure alignment of the nav element, it's crucial to carefully manage these properties. However, mixing different units can be challenging unless supported by browsers that offer functionalities like calc. Consider trying the following adjustments or simplifying your layout:
body {
margin:0;
padding: 5em;
background: #333;
}
.nav {
position: relative;
right: calc(-11.8% + 5em + 7px);
}
For more details and testing, you can refer to the jsfiddle link provided: http://jsfiddle.net/up7HD/6/
It's unclear why you chose 11.8% and 5em for padding, as using ems can lead to inconsistent results across different browsers due to varying font sizes. Additionally, 11.8% may not center the metal box effectively or leave sufficient space for other elements on smaller screens.