:root {
  --bg: #f3f3f3;
  --panel: #ffffff;
  --text: #1a1a1a;
  --muted: #666666;
  --ring: #d0d0d0;
  --primary: #0078d4; /* blu Win11 */
  --danger: #d13438;
}

* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }
body {
  font-family: "Segoe UI", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.container { max-width: 980px; margin: 0 auto; padding: 20px; }
.app-header { margin-bottom: 16px; }
.app-header h1 { margin: 0; font-size: 1.8rem; }

.grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}
@media (min-width: 900px) {
  .grid { grid-template-columns: 1fr 1fr; }
}

.card {
  background: var(--panel);
  border: 1px solid var(--ring);
  border-radius: 12px;
  padding: 16px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.1);
}

label { display: block; margin: 12px 0 6px; font-weight: 500; }
input[type=number] {
  width: 100%;
  padding: 10px;
  border-radius: 8px;
  border: 1px solid var(--ring);
  background: #fff;
  color: var(--text);
}
input[type=number]:focus {
  border-color: var(--primary);
  outline: none;
  box-shadow: 0 0 0 2px rgba(0,120,212,.3);
}

.btn-row { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }
.btn {
  border: 1px solid var(--ring);
  background: #f9f9f9;
  color: var(--text);
  padding: 8px 14px;
  border-radius: 6px;
  cursor: pointer;
  transition: background 0.2s;
}
.btn:hover { background: #e6e6e6; }
.btn.primary {
  background: var(--primary);
  border-color: transparent;
  color: #fff;
}
.btn.danger {
  background: var(--danger);
  border-color: transparent;
  color: #fff;
}
.btn.ghost {
  background: transparent;
}

.result { min-height: 1.6em; margin-top: 8px; font-weight: 600; }

.chart-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 10px;
}

.app-footer {
  text-align: center;
  color: var(--muted);
  margin-top: 18px;
}