.cu-div-border1{border: 1px solid;}
.cu-div-border2{border: 2px solid;}
.cu-div-border3{border: 3px solid;}
.cu-div-border4{border: 4px solid;}
.cu-div-border5{border: 5px solid;}
.cu-div-border6{border: 6px solid;}
.cu-div-border7{border: 7px solid;}
.cu-div-border8{border: 8px solid;}
.cu-div-border9{border: 9px solid;}
.cu-div-border10{border: 10px solid;}

.cu-div-padding1{padding:1px;}
.cu-div-padding5{padding:5px;}
.cu-div-padding10{padding:10px;}
.cu-div-padding15{padding:15px;}
.cu-div-padding20{padding:20px;}
.cu-div-padding25{padding:25px;}
.cu-div-padding30{padding:30px;}

.cu-div-border-black{border-color: #000000;}
.cu-div-border-red{border-color: #ff0000;}
.cu-div-border-green{border-color: #00ff00;}
.cu-div-border-blue{border-color: #0000ff;}
.cu-div-border-brown{border-color: brown;}
.cu-div-border-gray1{border-color:#666;}
.cu-div-border-gray2{border-color:#999;}
.cu-div-border-gray3{border-color:#ccc;}
.cu-div-border-violet{border-color:#9334D8;}

html.dark-mode {
  filter: invert(100%) hue-rotate(180deg);
}

/* 사진, 동영상 등 반전되면 안 되는 요소는 한 번 더 반전시켜 원상복구 */
html.dark-mode img, 
html.dark-mode video, 
html.dark-mode iframe {
  filter: invert(100%) hue-rotate(180deg);
}