| // nvue下hover-class无效 | 
| $u-button-before-top:50% !default; | 
| $u-button-before-left:50% !default; | 
| $u-button-before-width:100% !default; | 
| $u-button-before-height:100% !default; | 
| $u-button-before-transform:translate(-50%, -50%) !default; | 
| $u-button-before-opacity:0 !default; | 
| $u-button-before-background-color:#000 !default; | 
| $u-button-before-border-color:#000 !default; | 
| $u-button-active-before-opacity:.15 !default; | 
| $u-button-icon-margin-left:4px !default; | 
| $u-button-plain-u-button-info-color:$u-info; | 
| $u-button-plain-u-button-success-color:$u-success; | 
| $u-button-plain-u-button-error-color:$u-error; | 
| $u-button-plain-u-button-warning-color:$u-error; | 
|   | 
| .u-button { | 
|     width: 100%; | 
|      | 
|     &__text { | 
|         white-space: nowrap; | 
|         line-height: 1; | 
|     } | 
|      | 
|     &:before { | 
|         position: absolute; | 
|         top:$u-button-before-top; | 
|         left:$u-button-before-left; | 
|         width:$u-button-before-width; | 
|         height:$u-button-before-height; | 
|         border: inherit; | 
|         border-radius: inherit; | 
|         transform:$u-button-before-transform; | 
|         opacity:$u-button-before-opacity; | 
|         content: " "; | 
|         background-color:$u-button-before-background-color; | 
|         border-color:$u-button-before-border-color; | 
|     } | 
|      | 
|     &--active { | 
|         &:before { | 
|             opacity: .15 | 
|         } | 
|     } | 
|      | 
|     &__icon+&__text:not(:empty), | 
|     &__loading-text { | 
|         margin-left:$u-button-icon-margin-left; | 
|     } | 
|      | 
|     &--plain { | 
|         &.u-button--primary { | 
|             color: $u-primary; | 
|         } | 
|     } | 
|      | 
|     &--plain { | 
|         &.u-button--info { | 
|             color:$u-button-plain-u-button-info-color; | 
|         } | 
|     } | 
|      | 
|     &--plain { | 
|         &.u-button--success { | 
|             color:$u-button-plain-u-button-success-color; | 
|         } | 
|     } | 
|      | 
|     &--plain { | 
|         &.u-button--error { | 
|             color:$u-button-plain-u-button-error-color; | 
|         } | 
|     } | 
|      | 
|     &--plain { | 
|         &.u-button--warning { | 
|             color:$u-button-plain-u-button-warning-color; | 
|         } | 
|     } | 
| } |