body 直下(border:10px /box-sizing:border-box)

width:100%
width:100vw

#wrapper1(幅指定なし)

width:100%
width:100vw

#wrapper2 (max-width:640px; margin: 50px 0;)

width:100%
width:100vw

#wrapper3 (max-width:640px; margin: 50px auto;)

width:100%
width:100vw
width:100vw / calc(((100vw - 100%)/2 * -1) + 8px)

#wrapper4 (max-width: 640px; padding: 50px;)

width:100%
width:100vw