自訂通用類別 (utilities)
              width
              
                - responsive: trnu,
 
                - 5: 5%,
 
                - 10: 10%,
 
                - 15: 15%,
 
                - 20: 20%,
 
                - 25: 25%,
 
                - 30: 30%,
 
                - 35: 35%,
 
                - 40: 40%,
 
                - 45: 45%,
 
                - 50: 50%,
 
                - 55: 55%,
 
                - 60: 60%,
 
                - 65: 65%,
 
                - 70: 70%,
 
                - 75: 75%,
 
                - 80: 80%,
 
                - 85: 85%,
 
                - 90: 90%,
 
                - 95: 95%,
 
                - 100: 100%,
 
                - auto: auto
 
              
              spacers (注意單位)
              由變數 $spacers 設定,以 4 px 做為基數。
              
                - 0: 0,
 
                - 1: 1spacer / 4,     (4 px)
 
                - 2: 1spacer / 2,     (8 px)
 
                - 3: 1spacer * .75,   (12 px)
 
                - 4: 1spacer,         (16 px)
 
                - 5: 1spacer * 1.25,  (20 px)
 
                - 6: 1spacer * 1.5,   (24 px)
 
                - 7: 1spacer * 1.75,  (28 px)
 
                - 8: 1spacer * 2,     (32 px)
 
                - 9: 1spacer * 2.25,  (36 px)
 
                - 10: 1spacer * 2.5,  (40 px)
 
                - 11: 1spacer * 2.75, (44 px)
 
                - 12: 1spacer * 3,    (48 px)
 
              
              font-size
              
                - responsive: true,
 
                - 1: 12px,
 
                - 2: 14px,
 
                - 3: 16px,
 
                - 4: 18px,
 
                - 5: 20px,
 
                - 6: 22px,
 
                - 7: 24px,
 
                - 8: 26px,
 
                - 9: 28px,
 
                - 10: 30px,
 
                - 11: 32px,
 
              
              font-weight
              
                - light: $font-weight-light, (lighter)
 
                - lighter: $font-weight-lighter, (300)
 
                - normal: $font-weight-normal, (400)
 
                - bold: $font-weight-bold, (700)
 
                - bolder: $font-weight-bolder, (bolder)
 
                - "100": 100,
 
                - "200": 200,
 
                - "300": 300,
 
                - "400": 400,
 
                - "500": 500,
 
                - "600": 600,
 
                - "700": 700,
 
                - "800": 800,
 
                - "900": 900
 
              
              line-height (注意單位)
              
                - responsive: true,
 
                - 1: 1,
 
                - sm: 1line-height-sm, (1.5)
 
                - base: 1line-height-base, (1.25)
 
                - lg: 1line-height-lg, (2)
 
                - 20: 20px,
 
                - 22: 22px,
 
                - 23: 23px,
 
                - 24: 24px,
 
                - 25: 25px,
 
                - 26: 26px,
 
                - 27: 27px,
 
                - 28: 28px,
 
                - 29: 29px,
 
                - 30: 30px,
 
                - 31: 31px,
 
                - 32: 32px,
 
                - 33: 33px,
 
                - 34: 34px,
 
                - 35: 35px,
 
                - 36: 36px,
 
                - 37: 37px,
 
                - 38: 38px,
 
                - 39: 39px,
 
                - 40: 40px,
 
                - 47: 47px,
 
                - 56: 56px,
 
              
              letter-spacing
              
                - responsive: true,
 
                - "normal": normal, (預設值,單字或段落間的水平距離為預設效果)
 
                - "inherit": inherit, (繼承自父層的 word-spacing 屬性值)
 
                - 0: 0px,
 
                - 017: 0.17px,
 
                - 020: 0.20px,
 
                - 060: 0.60px,
 
                - 070: 0.70px,
 
                - 080: 0.80px,
 
                - 100: 1.00px,
 
                - 160: 1.60px,
 
                - 175: 1.75px,
 
                - 190: 1.90px,
 
                - 200: 2.00px,
 
                - 225: 2.25px,
 
                - 300: 3px