styles.css

:root {
  --color-black: #121213;
  --color-white: #fff;
  --color-green: #538d4e;
  --color-yellow: #B59F3B;
  --color-gray-dark: #3A3A3C;
  --color-gray-light: #818384;
}

html { box-sizing: border-box; }
*, *:before, *:after { box-sizing: inherit; }

body {
  background: var(--color-black);
  color: var(--color-white);

  font-family: 'Clear Sans', 'Helvetica Neue', Arial, sans-serif;

  min-height: 100vh;
  margin: 0;

  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 2rem;
}

header { border-bottom: 1px solid var(--color-gray-dark); }

h1 {
  margin: 10px 0;
  padding: 0;
  text-align: center;
}

main {
  flex-grow: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.toaster {
  position: absolute;
  top: 10%;
  left: 50%;
  transform: translate(-50%, 0);
  pointer-events: none;
  width: fit-content;
}

.toaster ul {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.toast {
  background: var(--color-white);
  border-radius: 4px;
  color: var(--color-black);
  padding: 1rem;
  font-weight: bold;
  text-align: center;
  opacity: 1;
  transition: opacity 300ms cubic-bezier(0.645, 0.045, 0.355, 1);
}

.fade { opacity: 0; }

#board, #keyboard {
  display: flex;
  flex-direction: column;
  gap: 6px; /* Between each row */
  text-transform: uppercase;
}

#board ul,
#keyboard ul {
  display: flex;
  list-style: none;
  gap: 6px; /* Between each cell */
  padding: 0;
  margin: 0;
}

[data-status],
[data-key] {
  border: 2px solid var(--color-gray-dark);
  font-weight: 700;
  font-size: 2rem;
  line-height: 2rem;

  display: inline-flex;
  align-items: center;
  justify-content: center;

  height: 4rem;
  width: 4rem;

  user-select: none;
}

#keyboard {
  gap: 8px; /* Between each row */
  padding-bottom: 10px;
}

#keyboard ul { justify-content: center; }

[data-key] {
  background: var(--color-gray-light);
  border: none;
  border-radius: 4px;

  font-size: 1rem;

  height: 3.8rem;
  width: 2.8rem;

  cursor: pointer;

  transition: all .3s ease-in-out;
}

[data-key='Enter'] { width: 6rem; }

[data-key='Backspace'] {
  background-image: url(./backspace.svg);
  background-repeat: no-repeat;
  background-position: center;
  text-indent: -9999px;
  width: 4rem;
}

[data-status='filled']      { border: 1px solid var(--color-gray-light); }
[data-status='valid']       { background: var(--color-green); }
[data-status='invalid']     { background: var(--color-yellow); }
[data-status='none']        { background: var(--color-gray-dark); }

[data-animation='pop']      { animation: PopIn 100ms; }

@keyframes PopIn {
  from {
    transform: scale(0.8);
    opacity: 0;
  }
  40% {
    transform: scale(1.1);
    opacity: 1;
  }
}

[data-animation='flip']     { animation: Flip .50s ease-in; }

@keyframes Flip {
  from {
    transform: rotateX(0);
  }
  50% {
    transform: rotateX(-90deg);
  }
  to {
    transform: rotateX(0);
  }
}

[data-animation='invalid']  { animation: Shake 600ms; }

@keyframes Shake {
  10%, 90% {
    transform: translateX(-1px);
  }
  20%, 80% {
    transform: translateX(2px);
  }
  30%, 50%, 70% {
    transform: translateX(-4px);
  }
  40%, 60% {
    transform: translateX(4px);
  }
}