1, head and neck:
Look straight ahead and keep your eyes parallel to the top of the computer screen (or the top of the screen 1/3), so that when you need to look at the text or images at the bottom of the screen, your head will naturally droop without straining your neck.
2. Arms and elbows:
Your arms should be kept at a height that allows your shoulders to move freely back and forth, up and down, and you don't have to struggle to reach the mouse and keyboard. The ideal state of elbow is to bend at right angles, so that the forearm can be roughly parallel to the ground.
3. Legs:
Keep your feet firmly on the ground and your thighs are parallel to the ground. If your feet can't touch the ground, you can try to put a small bench or a thick book under your feet, so as to avoid tiptoeing and your feet won't move. Hip and knee bend 90, that is, the distance between thigh and calf needs to be kept at 90-110, so it is appropriate to open the hip joint comfortably.
Precautions for sedentary:
People are different in height and figure, so you need a chair that can be adjusted to suit your height. The movable chair back can help the back get a proper angle of rest and relaxation. Try not to use a chair that cannot be moved and adjusted.
The so-called correct sitting posture is very complicated and varies from person to person. Everyone has the most suitable and comfortable sitting posture, but the most important thing is to "sit well". Generally speaking, when sitting, keep your ankles at 90 degrees and lay flat on the ground. Many other details include the distance between the line of sight and the computer screen, the position and angle of the screen and keyboard, and the gesture of using the keyboard.