.sudoku-board {
 min-height: 22.75rem;
 margin-top: 3px;
 margin-bottom: 1em;
}

.sudoku-board-cell {
 display: inline-block;
 position: relative;
 border: 1px solid #ddd;
 background: white;
 max-width: 11.11111%;
}

[data-board-size="9"].sudoku-board .sudoku-board-cell:nth-of-type(9n+1) {
 border-left-width: 2px;
 border-left-color: #808080;
}

[data-board-size="9"].sudoku-board .sudoku-board-cell:nth-of-type(n):nth-of-type(-n+9) {
 border-top-width: 2px;
 border-top-color: #808080;
}

[data-board-size="9"].sudoku-board .sudoku-board-cell:nth-of-type(3n) {
 border-right-width: 2px;
 border-right-color: #808080;
}

[data-board-size="9"].sudoku-board .sudoku-board-cell:nth-of-type(n+19):nth-of-type(-n+27),
[data-board-size="9"].sudoku-board .sudoku-board-cell:nth-of-type(n+46):nth-of-type(-n+54),
[data-board-size="9"].sudoku-board .sudoku-board-cell:nth-of-type(n+73):nth-of-type(-n+81) {
 border-bottom-width: 2px;
 border-bottom-color: #808080;
}

.sudoku-board-cell input {
 background: none;
 font-size: 19.2px;
 font-size: 1.2rem;
 text-align: center;
 width: 2em;
 max-width: 100%;
 height: 2em;
 border: 0;
 position: relative;
 z-index: 1; /*on top of candidates*/
}

.sudoku-board-cell .highlight-val {
 color: #00d !important;
}

.sudoku-board-cell .board-cell--error {
 background: #d00 !important;
 color: #eee !important;
}

.sudoku-board-cell .candidates {
 display: none; /*hidden by default*/
 position: absolute;
 top: 0; bottom: 0; left: 0; right: 0;
 text-align: center;
 font-size: .75em;
 letter-spacing: -.5px;
 font-family: monospace, sans-serif;
 line-height: 0;
 text-align: justify;
}

.sudoku-board .candidates:after {
 content: "";
 display: inline-block;
 width: 100%;
}

@media(max-width: 23em){
 .sudoku-board .candidates {
  letter-spacing: -2px;
 }
}
 .showCandidates .candidates {
  display: block;
 }

.sudoku-board .candidates div {
 display: inline-block;
 width: 20%;
 line-height: 1.13;
 vertical-align: top;
 *display: inline;
 *zoom: 1;
}

.candidate--highlight {
 background-color: yellow;
}
.candidate--to-remove {
 background-color: red;
 color: white;
}

.sudokubutton1,.sudokubutton2,.sudokubutton3,.sudokubutton4,
.sudokubutton5,.sudokubutton6,.sudokubutton7 {
color: white;
-webkit-transition-duration: 0.3s;
transition-duration: 0.3s;
padding: 1px 6px;
}
.sudokubutton1 {
background-color: #3cbf71;
}
.sudokubutton2 {
background-color: #ff9224;
}
.sudokubutton3 {
background-color: #ff3c3c;
}
.sudokubutton4 {
background-color: #020202;
}
.sudokubutton5,.sudokubutton6 {
background-color: #4040ff;
}
.sudokubutton7 {
background-color: #899db6;
}
.sudokubutton1:hover,.sudokubutton2:hover,.sudokubutton3:hover,.sudokubutton4:hover,
.sudokubutton5:hover,.sudokubutton6:hover,.sudokubutton7:hover {
background-color: #EDEDED;
color: black;
cursor: pointer;
}

* {
 margin:0; padding:0;
 -moz-box-sizing: border-box;
 -webkit-box-sizing: border-box;
 box-sizing: border-box;
}

.wrap {
 padding: 2em 1em;
 width: 400px;
 max-width: 100%;
 margin-left: auto;
 margin-right: auto;
}

@media(min-width: 30em) {
 .wrap {
  width: 490px;
 }
 .sudoku-board input {
  font-size: 24px;
  font-size: 1.5rem;
 }
 .sudoku-board .candidates {
  font-size: .8em;
 }
}