:root {
  --primary: #1e40af;
  --primary-hover: #1d4ed8;
  --bg: #f1f5f9;
  --card: #ffffff;
  --text: #1e293b;
  --muted: #64748b;
  --border: #cbd5e1;
  --accent-bg: #eff6ff;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

body {
  background-color: var(--bg);
  color: var(--text);
  padding: 20px;
  line-height: 1.5;
}

.container {
  max-width: 880px;
  margin: 0 auto;
}

header {
  text-align: center;
  margin-bottom: 24px;
}

header h1 {
  font-size: 1.75rem;
  color: var(--primary);
  margin-bottom: 6px;
}

header p {
  color: var(--muted);
  font-size: 0.95rem;
}

/* Навигация по вкладкам */
.tabs {
  display: flex;
  gap: 8px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.tab-btn {
  flex: 1;
  min-width: 140px;
  padding: 11px 14px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text);
  cursor: pointer;
  transition: all 0.2s;
}

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

.tab-btn.active {
  background: var(--primary);
  color: #ffffff;
  border-color: var(--primary);
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

/* Карточки калькуляторов */
.calc-card {
  background: var(--card);
  border-radius: 12px;
  padding: 24px;
  margin-bottom: 20px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.08);
}

.calc-card h2 {
  font-size: 1.15rem;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
  color: var(--primary);
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 16px;
  margin-bottom: 16px;
}

.form-group {
  display: flex;
  flex-direction: column;
}

label {
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--text);
}

input[type="number"], select {
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 0.95rem;
  transition: border-color 0.2s;
  background-color: #ffffff;
}

input[type="number"]:focus, select:focus {
  outline: none;
  border-color: var(--primary);
}

.checkbox-group {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 16px;
  font-size: 0.9rem;
  cursor: pointer;
}

/* Блок результатов */
.results {
  background: var(--accent-bg);
  border-left: 4px solid var(--primary);
  border-radius: 6px;
  padding: 16px;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  gap: 14px;
}

.res-item span {
  display: block;
  font-size: 0.8rem;
  color: var(--muted);
  margin-bottom: 2px;
}

.res-item strong {
  font-size: 1.2rem;
  color: var(--primary);
}