:root {
  --bg: #f6f8fc;
  --card: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --border: #dbe3f0;
  --primary: #2f6fed;
  --primary-dark: #2458bf;
  --selected: #dbe8ff;
  --pair: #f3f7ff;
  --suited: #f8fcff;
  --offsuit: #fcfcfd;
  --shadow: 0 10px 30px rgba(26, 40, 71, 0.08);
  --radius: 18px;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Arial, Helvetica, sans-serif;
}

body {
  padding: 16px;
}

.range-app {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
}

.app-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 24px;
  box-shadow: var(--shadow);
  padding: 24px;
}

.app-header h1 {
  margin: 0 0 8px;
  font-size: 2rem;
  line-height: 1.15;
}

.subtext {
  margin: 0;
  color: var(--muted);
  font-size: 1rem;
}

.top-controls {
  margin-top: 24px;
  display: grid;
  gap: 16px;
}

.field-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.field-group label,
.output-section label,
.preset-label {
  font-size: 0.95rem;
  font-weight: 700;
}

#rangeInput,
#rangeOutput {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 14px 16px;
  font-size: 1rem;
  background: #fff;
  color: var(--text);
}

#rangeInput:focus {
  outline: 2px solid rgba(47, 111, 237, 0.18);
  border-color: var(--primary);
}

.button-row,
.preset-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.btn {
  border: 1px solid var(--border);
  background: #fff;
  color: var(--text);
  border-radius: 12px;
  padding: 11px 16px;
  cursor: pointer;
  font-size: 0.95rem;
  transition: 0.15s ease;
}

.btn:hover {
  transform: translateY(-1px);
  border-color: #c8d3e6;
}

.btn-primary {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

.btn-primary:hover {
  background: var(--primary-dark);
  border-color: var(--primary-dark);
}

.btn-small {
  padding: 9px 13px;
  font-size: 0.9rem;
}

.preset-section,
.grid-section,
.summary-section,
.output-section,
.notes-section {
  margin-top: 24px;
}

.grid-header {
  display: flex;
  justify-content: space-between;
  align-items: end;
  gap: 12px;
  margin-bottom: 14px;
}

.grid-header h2 {
  margin: 0;
  font-size: 1.2rem;
}

.grid-help {
  color: var(--muted);
  font-size: 0.92rem;
}

.range-grid {
  display: grid;
  grid-template-columns: repeat(13, minmax(0, 1fr));
  gap: 6px;
}

.grid-cell {
  border: 1px solid var(--border);
  border-radius: 10px;
  min-height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 6px;
  font-weight: 700;
  font-size: 0.95rem;
  cursor: pointer;
  user-select: none;
  transition: 0.15s ease;
}

.grid-cell:hover {
  transform: translateY(-1px);
  border-color: #b9c8df;
}

.grid-cell.pair {
  background: var(--pair);
}

.grid-cell.suited {
  background: var(--suited);
}

.grid-cell.offsuit {
  background: var(--offsuit);
}

.grid-cell.selected {
  background: var(--selected);
  border-color: var(--primary);
  color: #1141a8;
  box-shadow: inset 0 0 0 1px rgba(47, 111, 237, 0.15);
}

.summary-section {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.summary-card {
  border: 1px solid var(--border);
  border-radius: 16px;
  background: #fff;
  padding: 18px;
}

.summary-title {
  color: var(--muted);
  font-size: 0.92rem;
  margin-bottom: 8px;
}

.summary-value {
  font-size: 1.5rem;
  font-weight: 800;
}

#rangeOutput {
  resize: vertical;
  min-height: 110px;
}

.notes-section {
  border-top: 1px solid var(--border);
  padding-top: 20px;
}

.notes-section h3 {
  margin: 0 0 12px;
  font-size: 1.05rem;
}

.notes-section ul {
  margin: 0;
  padding-left: 20px;
  color: var(--text);
}

.notes-section li {
  margin-bottom: 8px;
  line-height: 1.5;
}

@media (max-width: 900px) {
  .summary-section {
    grid-template-columns: 1fr;
  }

  .grid-cell {
    min-height: 44px;
    font-size: 0.84rem;
    padding: 4px;
  }
}

@media (max-width: 640px) {
  body {
    padding: 10px;
  }

  .app-card {
    padding: 16px;
    border-radius: 18px;
  }

  .app-header h1 {
    font-size: 1.55rem;
  }

  .grid-section {
    overflow-x: auto;
  }

  .range-grid {
    min-width: 560px;
  }
}