:root {
  --amarillo: #ffd400;
  --verde: #0a8f3c;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: #cfcfcf;
  font-family: Arial, sans-serif;
}

.app {
  padding: 10px;
}

#pizarra {
  background: #fff;
  border: 3px solid var(--verde);
  padding: 10px;
  max-width: 850px;
  margin: auto;
}

h1 {
  text-align: center;
  font-size: 22px;
  margin: 4px 0;
}

h2 {
  text-align: center;
  font-size: 14px;
  margin: 0 0 10px;
}

.info {
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  margin-bottom: 6px;
}

.grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
}

.header div {
  background: var(--amarillo);
  border: 1px solid var(--verde);
  font-weight: bold;
  text-align: center;
  padding: 6px;
}

.cell {
  border: 1px solid #aaa;
  height: 26px;
  line-height: 26px;
  text-align: center;
  background: white;
}

.cell:focus {
  outline: none;
  background: #fff6c2;
}

.controls {
  text-align: center;
  margin-top: 10px;
}

button {
  background: var(--verde);
  color: white;
  border: none;
  padding: 8px 14px;
  margin: 4px;
  font-size: 14px;
  border-radius: 4px;
}

.history {
  background: white;
  border: 2px solid var(--verde);
  padding: 10px;
  margin-top: 10px;
}

.history img {
  width: 100%;
  border: 1px solid #999;
  margin-bottom: 10px;
}

.hidden {
  display: none;
}