OS Details

Sony Xperia X has been launched in May 2016.
Sony Xperia X have Android 6.0.1 (Marshmallow) and planned upgrade to Android 8.0 (Oreo)

Screen Dimensions

Sony Xperia X screen size is 5.0 inch with ~ 69.8% body ratio of actual device size. Physical dimensions for Sony Xperia X device is 5.62 x 2.73 x 0.31 INCH or ( 142.7 x 69.4 x 7.9 MM).

Displaying of Units are in this order "Height x Width x Thickness"

Screen Pixel Density and CSS Pixel Ratio

"Pixel" is smallest unit/element of any display.

The total number of pixels that fit into an inch is referred to as "Screen Density" or "Pixel Density" and it measured as "Pixels Per Inch".
Pixel Desnsity have limits to display Pixels Per Inch depends on different screen sizes. When number of pixels per inch increases than it's screen-size limit, the Display resolution will increase but actual device width/height in pixels remain same. Actual device pixels are known as Device Independent Pixels or CSS Pixel Ratio.

Sony Xperia X resolution is 1080 x 1920 ^PX with ~ 441 pixel desnsity.
Sony Xperia X viewport size is 360 x 640 ^PX with ~ 147 actual pixel density, which means it have 3 xxhdpi display pixel density.

Screen Resolution and Viewport

The sum of pixels which are displaying on a device is called as "Screen Resolution". and sum of actual pixels of any device is reffered to as "Viewport".

Sony Xperia X have 5.0" physical screen size and its resolution is about 1080 x 1920 Pixels with approximately 441 PPI pixel density. Sony Xperia X has viewport size 360 x 640 Pixels and its pixel ratio is about 3.

For better understanding screen actual sizes, viewport sizes, display resolution and about their density click here.

CSS Media Queries

Sony Xperia X Media Queries (In terms of Mobile only)

@media only screen and (min-width: 360px) and (max-width: 767px) { /* Your Styles... */ }

Sony Xperia X Min-Width Media Queries

@media only screen and (min-width: 360px) { /* Your Styles... */ }

Sony Xperia X Min-Height Media Queries

@media only screen and (min-height: 640px) { /* Your Styles... */ }

Sony Xperia X Landscape Media Queries

@media only screen and (min-width: 640px) and (orientation: landscape) { /* Your Styles... */ }

Sony Xperia X Portrait Media Queries

@media only screen and (min-width: 360px) and (orientation: portrait) { /* Your Styles... */ }

Sony Xperia X Retina Media Queries

@media
  only screen and (-webkit-min-device-pixel-ratio: 3),
  only screen and (   min--moz-device-pixel-ratio: 3),
  only screen and (     -o-min-device-pixel-ratio: 3/1),
  only screen and (        min-device-pixel-ratio: 3),
  only screen and (                min-resolution: 441dpi),
  only screen and (                min-resolution: 3dppx) { 
    /* Retina styles here */
}
                                

Retina is actually based upon device pixel ratio. Devices mostly have 2x or 3x display so you can use general retina media queries to display high resolution content on all kind of devices. Retina 2x and Retina 3x media queries given below:

Retina 2x Media Query

@media
  only screen and (-webkit-min-device-pixel-ratio: 2),
  only screen and (   min--moz-device-pixel-ratio: 2),
  only screen and (     -o-min-device-pixel-ratio: 2/1),
  only screen and (        min-device-pixel-ratio: 2),
  only screen and (                min-resolution: 192dpi),
  only screen and (                min-resolution: 2dppx) { 
    /* Retina styles here */
}
                                

Retina 3x Media Query

@media
  only screen and (-webkit-min-device-pixel-ratio: 3),
  only screen and (   min--moz-device-pixel-ratio: 3),
  only screen and (     -o-min-device-pixel-ratio: 3/1),
  only screen and (        min-device-pixel-ratio: 3),
  only screen and (                min-resolution: 384dpi),
  only screen and (                min-resolution: 3dppx) { 
    /* Retina styles here */
}
                                

Sony Xperia X Specifications

• Launch Date May 2016
• Android 6.0.1 (Marshmallow)
• Physical Screen Size 5.0 INCH
• Resolution 1080 x 1920 PX
• Viewport Size 360 x 640 PX
• Pixel Density 441 PPI
• Device-Independent Pixels 147 PPI
• Pixel Ratio 3 xxhdpi
• Width 1080 PX
• Height 1920 PX
• Device Width 360 PX
• Device Height 640 PX
• Dimensions 142.7 x 69.4 x 7.9 mm (5.62 x 2.73 x 0.31 in)
• Weight 153 g - 5.40 oz