:root {
  --body: #d8d8d8;
  --panel: #202020;
  --panel-2: #2b2b2b;
  --screen: #d8e7b8;
  --screen-text: #1b2a12;
  --screen-dim: #5b6f45;
  --key: #3a3a3a;
  --key-text: #f2f2f2;
  --accent: #8cff6d;
  --border: #111;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Arial, sans-serif;
  background: linear-gradient(180deg, #efefef, var(--body));
  color: #111;
}

.wrap {
  max-width: 980px;
  margin: 0 auto;
  padding: 24px;
}

.calc {
  background: linear-gradient(180deg, #2f2f2f, #1f1f1f);
  border: 1px solid #111;
  border-radius: 20px;
  padding: 18px;
  box-shadow: 0 18px 48px rgba(0, 0, 0, 0.25);
}

.brand {
  color: #fafafa;
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 12px;
  gap: 12px;
}

.brand h1 {
  margin: 0;
  font-size: 18px;
  letter-spacing: 0.06em;
}

.brand small {
  color: #c9c9c9;
}

.screen {
  background: linear-gradient(180deg, #dbe8b8, var(--screen));
  color: var(--screen-text);
  border: 2px inset #8aa36b;
  border-radius: 10px;
  padding: 14px;
  min-height: 190px;
  font-family: "Courier New", monospace;
  display: grid;
  grid-template-rows: auto auto 1fr;
  gap: 10px;
}

.screen-top {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  font-size: 12px;
  color: var(--screen-dim);
}

.stack {
  border-top: 1px solid rgba(27, 42, 18, 0.35);
  padding-top: 10px;
  line-height: 1.5;
  font-size: 18px;
  white-space: pre-wrap;
}

.stack-line {
  display: grid;
  grid-template-columns: 26px 1fr;
  gap: 8px;
  padding: 1px 4px;
  border-radius: 4px;
}

.stack-line.selected {
  background: rgba(27, 42, 18, 0.14);
  outline: 1px dashed rgba(27, 42, 18, 0.45);
}

.stack-line.moving {
  background: rgba(140, 255, 109, 0.18);
  outline: 1px solid rgba(27, 42, 18, 0.55);
}

.stack-line .label {
  text-align: right;
  color: var(--screen-dim);
}

.stack-line.selected .label,
.stack-line.moving .label {
  color: var(--screen-text);
  font-weight: bold;
}

.hidden-input {
  position: absolute;
  left: -9999px;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}

.input-row {
  display: grid;
  grid-template-columns: 1fr 150px;
  gap: 12px;
  margin-top: 14px;
}

input, select, button {
  border-radius: 10px;
  border: 1px solid #000;
  font: inherit;
}

input, select {
  padding: 12px 14px;
  background: #f7f7f7;
  color: #111;
}

.panel {
  margin-top: 14px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 14px;
  padding: 14px;
}

.title {
  color: #fff;
  margin: 0 0 10px;
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.buttons {
  display: grid;
  gap: 8px;
  grid-template-columns: repeat(auto-fit, minmax(92px, 1fr));
}

button {
  padding: 12px 10px;
  background: linear-gradient(180deg, #4a4a4a, var(--key));
  color: var(--key-text);
  cursor: pointer;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.08);
}

button:hover { filter: brightness(1.08); }
button:active { transform: translateY(1px); }

.status {
  margin-top: 12px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  color: #ececec;
  font-size: 13px;
}

.pill {
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-radius: 999px;
  padding: 5px 10px;
  background: rgba(255, 255, 255, 0.05);
}

.error {
  margin-top: 10px;
  min-height: 20px;
  color: #ff8a8a;
  font-family: "Courier New", monospace;
  font-size: 13px;
}

.hint {
  color: #ddd;
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.5;
}