.formulas-container {
  max-width: 720px;
  margin: 0 auto;
}

.formulas-header {
  text-align: center;
  margin-bottom: 2rem;
}

.formulas-header h2 {
  font-size: 1.7rem;
  color: var(--text-main);
  margin-bottom: 0.25rem;
}

.formulas-header .subtitle {
  color: var(--text-muted);
  font-size: 0.95rem;
}

.formula-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.formula-title {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin-bottom: 0.5rem;
}

.formula-icon {
  font-size: 1.4rem;
}

.formula-card h3 {
  font-size: 1.15rem;
  color: var(--text-main);
  margin: 0;
}

.formula-card p {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.math-box {
  background-color: #f1f5f9;
  border-left: 4px solid var(--primary);
  padding: 0.85rem 1rem;
  border-radius: 4px;
  font-family: 'Courier New', Courier, monospace;
  font-weight: 700;
  font-size: 0.95rem;
  color: #0f172a;
  margin-bottom: 1rem;
  line-height: 1.4;
}

.example-box {
  background-color: var(--bg-body);
  border: 1px dashed var(--border);
  padding: 0.85rem 1rem;
  border-radius: 6px;
  font-size: 0.85rem;
  color: var(--text-main);
}

.example-box ul {
  margin-top: 0.5rem;
  padding-left: 1.2rem;
  margin-bottom: 0;
}

.example-box li {
  margin-bottom: 0.25rem;
}

.tool-desc {
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  font-size: 0.95rem;
}

.calculator {
  max-width: 320px;
  margin: 0 auto;
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  box-shadow: 0 10px 15px -3px rgba(0,0,0,0.08);
}

.calc-display {
  width: 100%;
  height: 60px;
  background-color: var(--ad-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 1.8rem;
  font-weight: 700;
  text-align: right;
  padding: 0 1rem;
  margin-bottom: 1rem;
  color: var(--text-main);
}

.calc-buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.5rem;
}

.calc-buttons button {
  height: 50px;
  font-size: 1.2rem;
  font-weight: 600;
  border: 1px solid var(--border);
  border-radius: 8px;
  background-color: var(--surface);
  color: var(--text-main);
  cursor: pointer;
  transition: all 0.15s ease;
}

.calc-buttons button:hover {
  background-color: var(--ad-bg);
  border-color: #cbd5e1;
}

.calc-buttons button:active {
  transform: scale(0.96);
}

.calc-buttons .btn-op {
  background-color: #eff6ff;
  color: var(--primary);
}

.calc-buttons .btn-func {
  background-color: #f1f5f9;
  color: #dc2626;
}

.calc-buttons .btn-equal {
  background-color: var(--primary);
  color: white;
  border: none;
}

.calc-buttons .btn-equal:hover {
  background-color: var(--primary-hover);
}

.calc-buttons .btn-zero {
  grid-column: span 2;
}