/* ─── Layakari Calculator ─── */
.calc-shell {
  min-height: 100vh;
  padding: 0 24px 32px;
  display: flex;
  flex-direction: column;
  background: var(--bg-surface, #faf8f4);
}

[data-theme="dark"] .calc-shell {
  background: var(--bg-surface, #141a2e);
}

.calc-header {
  max-width: 800px;
  width: 100%;
  margin: 0 auto;
  padding: calc(20px + max(env(safe-area-inset-top, 0px), var(--safe-area-inset-top, 0px))) 0 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  border-bottom: 1px solid var(--border-color);
  box-shadow: inset 0 -1px 0 rgba(255, 255, 255, 0.04);
}

.calc-header-left {
  display: flex;
  align-items: center;
  gap: 12px;
}

.calc-brand {
  color: var(--accent-primary);
  text-decoration: none;
  font-family: var(--font-system);
  font-size: 1.3rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 8px;
}

.calc-brand .theme-drum {
  height: 56px;
  width: auto;
  vertical-align: middle;
}

.calc-header-sep {
  color: var(--text-muted);
  opacity: 0.4;
}

.calc-title {
  font-family: var(--font-system);
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 0;
}

.calc-main {
  max-width: 800px;
  width: 100%;
  margin: 40px auto 0;
}

.calc-card {
  padding: 28px;
  border-radius: 20px;
  border: 1px solid var(--border-color);
  background: var(--bg-elevated);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.04), inset 0 1px 0 rgba(255, 255, 255, 0.06);
  transition: box-shadow 0.2s ease, border-color 0.2s ease;
}

.calc-card-title {
  font-family: var(--font-system);
  font-size: 1.4rem;
  font-weight: 700;
  margin: 0 0 24px;
  color: var(--text-primary);
  letter-spacing: -0.025em;
}

.calc-controls {
  display: flex;
  gap: 20px;
  margin-bottom: 28px;
}

.calc-group {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.calc-group label {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.calc-select {
  width: 100%;
  height: 44px; /* Mobile tap target standard */
  padding: 0 14px;
  font-size: 0.95rem;
  font-weight: 500;
  border-radius: 10px;
  border: 1px solid var(--border-color);
  background-color: var(--bg-input, rgba(255, 255, 255, 0.05));
  color: var(--text-primary);
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6' fill='none'%3E%3Cpath d='M1 1l4 4 4-4' stroke='%23888' stroke-width='1.3' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 14px center;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.03);
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.calc-select:hover {
  border-color: var(--border-strong);
}

.calc-select:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px var(--accent-subtle, rgba(234, 101, 0, 0.15));
}

.calc-results {
  display: flex;
  gap: 16px;
  padding: 22px;
  border-radius: 16px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.03);
  align-items: center;
  justify-content: space-around;
}

.calc-result-box {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  flex: 1;
}

.calc-result-box:not(:last-child) {
  border-right: 1px solid var(--border-color);
}

.calc-result-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--text-muted);
  font-weight: 600;
}

.calc-result-value {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.2;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.02em;
}

.calc-result-box-primary .calc-result-value {
  color: var(--accent-primary);
  font-size: 2rem;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.03em;
}

/* ─── Page Tabs — Apple Segmented Capsule ─── */
.calc-page-tabs {
  display: flex;
  gap: 4px;
  margin-bottom: 24px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 9999px;
  padding: 4px;
  box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.04);
}

.calc-page-tab {
  flex: 1;
  text-align: center;
  padding: 9px 16px;
  font-family: var(--font-system);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  text-decoration: none;
  border-radius: 9999px;
  transition: transform 0.16s cubic-bezier(0.16, 1, 0.3, 1), background 0.15s ease, color 0.15s ease, box-shadow 0.15s ease;
  cursor: pointer;
  letter-spacing: -0.01em;
  user-select: none;
}

.calc-page-tab:hover {
  color: var(--text-primary);
  background: var(--bg-glass-hover);
}

.calc-page-tab:active {
  transform: scale(0.97);
}

.calc-page-tab.is-active {
  color: var(--accent-primary);
  background: var(--bg-primary);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08), inset 0 1px 0 rgba(255, 255, 255, 0.12);
}

[data-theme="dark"] .calc-page-tab.is-active {
  color: var(--accent-primary);
  background: var(--bg-primary);
}

/* ─── Math Chain (textbook-style stacked fractions) ─── */
.calc-math-chain {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: center;
  margin: 16px 0 4px;
  padding: 20px 16px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 14px;
  box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.02);
  font-family: var(--font-system);
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1;
  font-variant-numeric: tabular-nums;
}

.calc-math-frac {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: 0;
  position: relative;
}

.calc-math-num {
  padding: 0 6px 4px;
}

.calc-math-den {
  padding: 4px 6px 0;
  border-top: 1.5px solid var(--text-muted, #888);
}

.calc-math-op {
  color: var(--text-muted);
  font-weight: 500;
  font-size: 1.1rem;
}

.calc-math-whole {
  padding: 0 2px;
}

.calc-math-mixed {
  display: inline-flex;
  align-items: center;
  gap: 3px;
}

.calc-math-result {
  color: var(--accent-primary);
}

/* ─── Responsive (Mobile-First approach overrides) ─── */
@media (max-width: 600px) {
  .calc-shell {
    padding: 0 16px 24px;
  }
  
  .calc-header {
    flex-wrap: wrap;
    gap: 12px;
  }
  
  .calc-brand {
    font-size: 1.1rem;
  }
  
  .calc-title {
    font-size: 1rem;
  }

  .calc-main {
    margin-top: 24px;
  }

  .calc-card {
    padding: 20px 16px;
  }

  .calc-controls {
    flex-direction: column;
    gap: 16px;
  }

  /* Keep Results side by side if possible, but shrink text, or stack */
  .calc-results {
    padding: 16px 12px;
    gap: 8px;
  }

  .calc-result-value {
    font-size: 1.2rem;
  }

  .calc-result-box-primary .calc-result-value {
    font-size: 1.6rem;
  }
  
  .calc-result-label {
    font-size: 0.65rem;
  }
}