:root {
  --bg: #fafafa;              /* lighter background */
  --card: #ffffff;
  --text: #333333;            /* darker text for readability */
  --muted: #777777;
  --accent: #007bff;          /* blue accent similar to many modern themes */
  --shadow: rgba(0,0,0,0.1);
  --font-base: 'Roboto', sans-serif;
}

html, body {
  height:100%;
  margin:0;
  padding:0;
  font-family: var(--font-base);
  background: var(--bg);
  color: var(--text);
}

.app {
  max-width: 1000px;
  margin: 40px auto;
  padding: 20px;
}

.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 20px;
  border-bottom: 1px solid #e0e0e0;
}

.brand h1 {
  margin: 0;
  font-size: 28px;
  font-weight: 700;
}

.brand .tag {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 16px;
}

.theme-toggle label {
  font-size: 14px;
}

.main {
  display: grid;
  grid-template-columns: 380px 1fr;
  gap: 30px;
  margin-top: 30px;
}

.controls {
  background: var(--card);
  padding: 24px;
  border-radius: 8px;
  box-shadow: 0 4px 20px var(--shadow);
}

.results {
  background: var(--card);
  padding: 24px;
  border-radius: 8px;
  box-shadow: 0 4px 20px var(--shadow);
}

.row {
  display: flex;
  gap: 16px;
  align-items: center;
  margin-bottom: 16px;
}

.row.small {
  gap: 12px;
}

label {
  display: flex;
  flex-direction: column;
  font-size: 14px;
  flex: 1;
}

input[type=number],
select {
  padding: 10px;
  border-radius: 6px;
  border: 1px solid #ccc;
  background: #fff;
  min-width: 140px;
  font-size: 14px;
}

.actions {
  display: flex;
  gap: 12px;
  margin-top: 12px;
}

.btn {
  padding: 10px 16px;
  border-radius: 6px;
  border: 1px solid #007bff;
  background: transparent;
  color: var(--accent);
  font-size: 14px;
  cursor: pointer;
}

.btn.primary {
  background: var(--accent);
  color: #ffffff;
  border: none;
}

.cards {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.card {
  flex: 1 1 160px;
  padding: 14px;
  border-radius: 6px;
  border: 1px solid #e8e8e8;
  background: #fff;
}

.card h3 {
  margin: 0 0 8px;
  font-size: 14px;
}

.card p {
  margin: 0;
  font-weight: 600;
  font-size: 20px;
}

.more {
  margin-top: 20px;
}

.export {
  display: flex;
  gap: 12px;
  margin-top: 16px;
}

.footer {
  text-align: center;
  margin-top: 40px;
  color: var(--muted);
  font-size: 13px;
}

/* Responsive */
@media (max-width: 900px) {
  .main {
    grid-template-columns: 1fr;
  }
}

/* Dark theme override */
body.dark {
  --bg: #1a1a1a;
  --card: #2a2a2a;
  --text: #f1f1f1;
  --muted: #aaaaaa;
  --accent: #4dabf7;
  --shadow: rgba(0,0,0,0.5);
}