html { height: 100%; }

body {
  background-color: black;
  margin: 0;
  padding: 0;
  font-size: 10px;
  font-family: sans-serif;
  height: 100%;
}

@media (min-width: 400px) and (min-height: 400px) {
  html { font-size: 20px; }
}

@media (min-width: 500px) and (min-height: 500px) {
  html { font-size: 30px; }
}

@media (min-width: 600px) and (min-height: 600px) {
  html { font-size: 40px; }
}

@media (min-width: 800px) and (min-height: 800px) {
  html { font-size: 50px; }
}

#root {
  display: flex;
  flex-direction: column;
  flex-wrap: wrap;
  height: 100%;
}

#display {
  background-color: #858694;
  color: white;
  text-align: right;
  font-weight: 200;
  flex: 0 0 auto;
  width: 100%;
}

#display > div {
  font-size: 2.5rem;
  padding: 0.2rem 0.7rem 0.1rem 0.5rem;
}

#panel {
  background-color: #858694;
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
  flex: 1 0 auto;
}

#panel > div {
  width: 100%;
  margin-bottom: 1px;
  flex: 1 0 auto;
  display: -ms-flexbox;
  display: flex;
}

.button {
  display: inline-flex;
  width: 25%;
  flex: 1 0 auto;
}

.button.wide { width: 50%; }

.button button {
  background-color: #e0e0e0;
  border: 0;
  font-size: 1.5rem;
  margin: 0 1px 0 0;
  flex: 1 0 auto;
  padding: 0;
}

.button:last-child button {
  margin-right: 0;
  background-color: #f5923e;
  color: white;
}