h1 {
  color: #585858;
  box-sizing: inherit;
  padding: 0;
  border: 0;
  font: inherit;
  vertical-align: baseline;
  font-size: 2.75em;
  font-weight: 700;
  line-height: 1.3;
  display: flex;
  justify-content: center;
  letter-spacing: -0.035em;
}

html, body {
    background-color: #FAFAFA
}

  table {
    border: 2px solid #000000;
}

td {
  border: 1px solid #000000;
  text-align: center;
  vertical-align: middle;  
}

#grid {
  margin: auto;
}

input {
  color: #000000;
  padding: 0;
  border: 0;
  text-align: center;
  width: 48px;
  height: 48px;
  font-size: 24px;
  background-color: #FFFFFF;
  outline: none;
}

input:disabled {
  background-color: #EEEEEE;
}

#button {
  display: flex;
  justify-content: center;
}
button {
  margin: 10px;
}

#cell-0,  #cell-1,  #cell-2  { border-top:    2px solid #000000; }
#cell-2,  #cell-11, #cell-20 { border-right:  2px solid #000000; }
#cell-18, #cell-19, #cell-20 { border-bottom: 2px solid #000000; }
#cell-0,  #cell-9,  #cell-18 { border-left:   2px solid #000000; }

#cell-3,  #cell-4,  #cell-5  { border-top:    2px solid #000000; }
#cell-5,  #cell-14, #cell-23 { border-right:  2px solid #000000; }
#cell-21, #cell-22, #cell-23 { border-bottom: 2px solid #000000; }
#cell-3,  #cell-12, #cell-21 { border-left:   2px solid #000000; }

#cell-6,  #cell-7,  #cell-8  { border-top:    2px solid #000000; }
#cell-8,  #cell-17, #cell-26 { border-right:  2px solid #000000; }
#cell-24, #cell-25, #cell-26 { border-bottom: 2px solid #000000; }
#cell-6,  #cell-15, #cell-24 { border-left:   2px solid #000000; }

#cell-27, #cell-28, #cell-29 { border-top:    2px solid #000000; }
#cell-29, #cell-38, #cell-47 { border-right:  2px solid #000000; }
#cell-45, #cell-46, #cell-47 { border-bottom: 2px solid #000000; }
#cell-27, #cell-36, #cell-45 { border-left:   2px solid #000000; }

#cell-30, #cell-31, #cell-32 { border-top:    2px solid #000000; }
#cell-32, #cell-41, #cell-50 { border-right:  2px solid #000000; }
#cell-48, #cell-49, #cell-50 { border-bottom: 2px solid #000000; }
#cell-30, #cell-39, #cell-48 { border-left:   2px solid #000000; }

#cell-33, #cell-34, #cell-35 { border-top:    2px solid #000000; }
#cell-35, #cell-44, #cell-53 { border-right:  2px solid #000000; }
#cell-51, #cell-52, #cell-53 { border-bottom: 2px solid #000000; }
#cell-33, #cell-42, #cell-51 { border-left:   2px solid #000000; }

#cell-54, #cell-55, #cell-56 { border-top:    2px solid #000000; }
#cell-56, #cell-65, #cell-74 { border-right:  2px solid #000000; }
#cell-72, #cell-73, #cell-74 { border-bottom: 2px solid #000000; }
#cell-54, #cell-63, #cell-72 { border-left:   2px solid #000000; }

#cell-57, #cell-58, #cell-59 { border-top:    2px solid #000000; }
#cell-59, #cell-68, #cell-77 { border-right:  2px solid #000000; }
#cell-75, #cell-76, #cell-77 { border-bottom: 2px solid #000000; }
#cell-57, #cell-66, #cell-75 { border-left:   2px solid #000000; }

#cell-60, #cell-61, #cell-62 { border-top:    2px solid #000000; }
#cell-62, #cell-71, #cell-80 { border-right:  2px solid #000000; }
#cell-78, #cell-79, #cell-80 { border-bottom: 2px solid #000000; }
#cell-60, #cell-69, #cell-78 { border-left:   2px solid #000000; }

#footer {
  color: #585858;
  box-sizing: inherit;
  margin: 0;
  border: 0;
  font-size: 100%;
  font: inherit;
  vertical-align: baseline;
  display: block;
  background-color: #f6f6f6;
  padding: 5em 0 3em 0;
}

#footer > div {
  color: #585858;
  box-sizing: inherit;
  border: 0;
  font-size: 100%;
  font: inherit;
  vertical-align: baseline;
  display: flex;
  flex-wrap: wrap;
  flex-direction: row;
  width: 100%;
  max-width: 68em;
  margin: 0 auto;
  padding: 0 2.5em;
}

#footer > div > ul {
  box-sizing: inherit;
  border: 0;
  font: inherit;
  vertical-align: baseline;
  margin: 0 0 2em 0;
  width: 100%;
  padding: 0;
  margin-top: 5em;
  list-style: none;
  font-size: 0.8em;
  color: rgba(88, 88, 88, 0.5);
}

#footer > div > ul > li:nth-child(1) {
  list-style: none;
  color: rgba(88, 88, 88, 0.5);
  box-sizing: inherit;
  border: 0;
  font-size: 100%;
  font: inherit;
  vertical-align: baseline;
  display: inline-block;
  line-height: 1;
  padding: 0 0 0 1em;
  margin: 0 0 0 1em;
  border-left: 0;
  padding-left: 0;
  margin-left: 0;
}

#footer > div > ul > li:nth-child(2) {
  list-style: none;
  color: rgba(88, 88, 88, 0.5);
  box-sizing: inherit;
  border: 0;
  font-size: 100%;
  font: inherit;
  vertical-align: baseline;
  display: inline-block;
  border-left: solid 1px rgba(88, 88, 88, 0.15);
  line-height: 1;
  padding: 0 0 0 1em;
  margin: 0 0 0 1em;
}

button {
  border-radius: 8px;
  padding: 5px 10px;
  box-shadow: 2px 2px #585858;
  box-sizing: inherit;
  font: inherit;
  color: #585858;
}