/* ===================================================================
   QME Combined Calculator — app.css
   Single consolidated stylesheet. "Clinical Precision" aesthetic.
   =================================================================== */

/* ===== 1. CSS CUSTOM PROPERTIES ===== */

:root {
  /* Colors — Light Theme */
  --color-bg-page: #F7F5F2;
  --color-bg-surface: #FFFFFF;
  --color-bg-elevated: #FAFAF8;
  --color-bg-inset: #F0EEED;
  --color-text-primary: #1A1A2E;
  --color-text-secondary: #5A5A72;
  --color-text-muted: #8E8E9E;
  --color-border: #E2E0DC;
  --color-border-focus: #2563EB;
  --color-accent: #2563EB;
  --color-accent-hover: #1D4ED8;
  --color-accent-subtle: rgba(37, 99, 235, 0.08);
  --color-accent-glow: rgba(37, 99, 235, 0.2);
  --color-success: #059669;
  --color-success-subtle: rgba(5, 150, 105, 0.08);
  --color-error: #DC2626;
  --color-error-subtle: rgba(220, 38, 38, 0.08);
  --color-warning: #D97706;
  --color-warning-subtle: rgba(217, 119, 6, 0.08);
  --color-result-bg: #F0F7FF;
  --color-result-accent: #2563EB;
  --color-overlay: rgba(15, 15, 26, 0.6);

  /* Shadows */
  --shadow-xs: 0 1px 2px rgba(26, 26, 46, 0.04);
  --shadow-sm: 0 1px 3px rgba(26, 26, 46, 0.06), 0 1px 2px rgba(26, 26, 46, 0.04);
  --shadow-md: 0 4px 12px rgba(26, 26, 46, 0.08);
  --shadow-lg: 0 8px 24px rgba(26, 26, 46, 0.12);
  --shadow-xl: 0 16px 48px rgba(26, 26, 46, 0.16);

  /* Radii */
  --radius-xs: 4px;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-xl: 20px;

  /* Typography */
  --font-heading: 'DM Serif Display', Georgia, 'Times New Roman', serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', 'Consolas', monospace;

  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.25s ease;
  --transition-slow: 0.4s ease;
}

/* ===== DARK THEME ===== */

.dark-theme {
  --color-bg-page: #0F0F1A;
  --color-bg-surface: #1A1A2E;
  --color-bg-elevated: #232340;
  --color-bg-inset: #151528;
  --color-text-primary: #E8E6F0;
  --color-text-secondary: #A8A6B8;
  --color-text-muted: #6B6980;
  --color-border: #2D2D48;
  --color-border-focus: #60A5FA;
  --color-accent: #60A5FA;
  --color-accent-hover: #93C5FD;
  --color-accent-subtle: rgba(96, 165, 250, 0.10);
  --color-accent-glow: rgba(96, 165, 250, 0.25);
  --color-success: #34D399;
  --color-success-subtle: rgba(52, 211, 153, 0.10);
  --color-error: #F87171;
  --color-error-subtle: rgba(248, 113, 113, 0.10);
  --color-warning: #FBBF24;
  --color-warning-subtle: rgba(251, 191, 36, 0.10);
  --color-result-bg: #1E2A4A;
  --color-result-accent: #60A5FA;
  --color-overlay: rgba(0, 0, 0, 0.7);
  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.15);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.2), 0 1px 2px rgba(0, 0, 0, 0.15);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.4);
  --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.5);
}


/* ===== 2. CSS RESET & BASE ===== */

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.6;
  color: var(--color-text-primary);
  background-color: var(--color-bg-page);
  transition: background-color var(--transition-base), color var(--transition-base);
  min-height: 100vh;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition-fast);
}
a:hover { color: var(--color-accent-hover); }

button {
  font-family: var(--font-body);
  cursor: pointer;
  border: none;
  background: none;
  font-size: inherit;
  color: inherit;
}

input, select, textarea {
  font-family: var(--font-body);
  font-size: 16px; /* Prevents iOS zoom */
  color: var(--color-text-primary);
}

ul { list-style: none; }

img { max-width: 100%; display: block; }


/* ===== 3. TYPOGRAPHY ===== */

h1 {
  font-family: var(--font-heading);
  font-size: 1.75rem;
  font-weight: 400;
  letter-spacing: -0.01em;
  line-height: 1.2;
  color: var(--color-text-primary);
}

h2 {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 400;
  line-height: 1.3;
  color: var(--color-text-primary);
}

h3 {
  font-family: var(--font-body);
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--color-text-primary);
}

.section-label {
  font-family: var(--font-body);
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  margin-bottom: var(--space-md);
}


/* ===== 4. LAYOUT ===== */

.app-shell {
  max-width: 720px;
  margin: 0 auto;
  padding: var(--space-lg) var(--space-lg) var(--space-2xl);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.calculator-main {
  flex: 1;
}


/* ===== 5. HEADER ===== */

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md) 0 var(--space-lg);
  border-bottom: 1px solid var(--color-border);
  margin-bottom: var(--space-lg);
  gap: var(--space-md);
}

.header-brand h1 {
  font-size: 1.5rem;
  margin-bottom: 2px;
}

.header-tagline {
  font-size: 12px;
  font-weight: 500;
  color: var(--color-text-muted);
  letter-spacing: 0.02em;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  flex-shrink: 0;
}

.account-chip {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 13px;
}

.account-chip .user-email {
  color: var(--color-text-secondary);
  max-width: 160px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.auth-button,
.logout-button {
  font-size: 13px;
  font-weight: 600;
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.auth-button {
  background: var(--color-accent);
  color: #fff;
}
.auth-button:hover {
  background: var(--color-accent-hover);
}

.logout-button {
  color: var(--color-text-muted);
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border);
}
.logout-button:hover {
  color: var(--color-error);
  border-color: var(--color-error);
  background: var(--color-error-subtle);
}

.icon-button {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
  transition: all var(--transition-fast);
  font-size: 16px;
}
.icon-button:hover {
  background: var(--color-accent-subtle);
  color: var(--color-accent);
}


/* ===== 6. SUBSCRIPTION BANNER ===== */

#subscriptionBanner {
  margin-bottom: var(--space-lg);
}

.subscription-strip {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  padding: 10px var(--space-md);
  border-radius: var(--radius-md);
  font-size: 14px;
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border);
  transition: all var(--transition-base);
}

/* Mobile toggle */
.subscription-toggle {
  display: none;
  align-items: center;
  justify-content: space-between;
  padding: 10px var(--space-md);
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  cursor: pointer;
  font-size: 13px;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}
.subscription-toggle:hover {
  border-color: var(--color-accent);
}
.subscription-toggle i {
  font-size: 12px;
  transition: transform var(--transition-base);
}

.subscription-details {
  /* Default visible on desktop */
}

/* Free plan banner */
.plan-banner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  padding: 10px var(--space-md);
  border-radius: var(--radius-md);
  font-size: 14px;
  flex-wrap: wrap;
}

.plan-banner.free-plan {
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border);
}

.plan-banner.free-plan-depleted {
  background: var(--color-warning-subtle);
  border: 1px solid var(--color-warning);
}

.plan-banner.paid-plan {
  background: var(--color-success-subtle);
  border: 1px solid var(--color-success);
}

.plan-banner h3 {
  font-size: 14px;
  font-weight: 600;
  margin: 0;
}

.plan-banner p {
  font-size: 13px;
  color: var(--color-text-secondary);
  margin: 2px 0 0 0;
}

.plan-info {
  flex: 1;
  min-width: 0;
}

.plan-action {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  flex-shrink: 0;
}

.plan-action p {
  margin: 0;
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.coffee-comparison {
  font-size: 12px;
  color: var(--color-text-muted);
  margin-top: 4px;
}

.email-reminder {
  font-size: 11px;
  color: var(--color-text-muted);
}

.upgrade-prompt {
  font-size: 13px;
}

/* Subscription buttons */
.btn.primary,
.subscribe-button,
#subscribeButton {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  font-size: 13px;
  font-weight: 600;
  border-radius: var(--radius-sm);
  background: var(--color-accent);
  color: #fff;
  border: none;
  cursor: pointer;
  text-decoration: none;
  white-space: nowrap;
  transition: all var(--transition-fast);
}
.btn.primary:hover,
.subscribe-button:hover,
#subscribeButton:hover {
  background: var(--color-accent-hover);
}

.btn.secondary,
.btn.grey {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  font-size: 13px;
  font-weight: 600;
  border-radius: var(--radius-sm);
  background: var(--color-bg-surface);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  cursor: pointer;
  text-decoration: none;
  white-space: nowrap;
  transition: all var(--transition-fast);
}
.btn.secondary:hover,
.btn.grey:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background: var(--color-accent-subtle);
}


/* ===== 7. CALCULATOR FORM ===== */

#calculatorContainer {
  background: var(--color-bg-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  box-shadow: var(--shadow-md);
}

.input-section {
  margin-bottom: var(--space-lg);
}

.input-fields,
.input-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-md) var(--space-lg);
}

.additional-fields {
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  transition: max-height var(--transition-slow), opacity var(--transition-base), margin var(--transition-base);
  margin-top: 0;
}

.additional-fields.expanded {
  max-height: 600px;
  opacity: 1;
  margin-top: var(--space-md);
}

.input-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.input-group label {
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-muted);
}

.input-group label .optional {
  font-weight: 400;
  text-transform: none;
  letter-spacing: normal;
  font-size: 11px;
  opacity: 0.7;
}

.input-group input[type="number"] {
  font-family: var(--font-mono);
  font-size: 18px;
  font-weight: 500;
  padding: 12px 16px;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-bg-elevated);
  color: var(--color-text-primary);
  text-align: center;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
  -moz-appearance: textfield;
  width: 100%;
}

.input-group input[type="number"]::-webkit-outer-spin-button,
.input-group input[type="number"]::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

.input-group input[type="number"]::placeholder {
  color: var(--color-text-muted);
  font-weight: 400;
  font-size: 14px;
  opacity: 0.6;
}

.input-group input[type="number"]:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-subtle);
  outline: none;
}

.input-group input[type="number"].valid {
  border-color: var(--color-success);
}

.input-group input[type="number"].invalid {
  border-color: var(--color-error);
  box-shadow: 0 0 0 3px var(--color-error-subtle);
}

/* Expand button */
.expand-button {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  width: 100%;
  padding: 12px;
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-md);
  background: transparent;
  color: var(--color-text-muted);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  margin: var(--space-md) 0 0;
}

.expand-button:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background: var(--color-accent-subtle);
}

.expand-button i {
  font-size: 12px;
  transition: transform var(--transition-base);
}

.expand-button.expanded i {
  transform: rotate(180deg);
}


/* ===== 8. BUTTONS ===== */

.button-section {
  display: flex;
  gap: var(--space-md);
  margin: var(--space-lg) 0;
}

.calculate-button {
  flex: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: 14px var(--space-lg);
  font-size: 16px;
  font-weight: 600;
  border-radius: var(--radius-md);
  background: var(--color-accent);
  color: #fff;
  transition: all var(--transition-fast);
  min-height: 48px;
  box-shadow: var(--shadow-sm), 0 0 0 0 var(--color-accent-glow);
}

.calculate-button:hover:not(:disabled) {
  background: var(--color-accent-hover);
  box-shadow: var(--shadow-md), 0 0 0 4px var(--color-accent-glow);
  transform: translateY(-1px);
}

.calculate-button:active:not(:disabled) {
  transform: translateY(0);
  box-shadow: var(--shadow-xs);
}

.calculate-button:disabled,
.calculate-button.disabled-button {
  opacity: 0.4;
  cursor: not-allowed;
  background: var(--color-text-muted);
  box-shadow: none;
}

.reset-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: 14px var(--space-lg);
  font-size: 16px;
  font-weight: 600;
  border-radius: var(--radius-md);
  background: var(--color-bg-elevated);
  color: var(--color-text-secondary);
  border: 1.5px solid var(--color-border);
  transition: all var(--transition-fast);
  min-height: 48px;
}

.reset-button:hover {
  border-color: var(--color-error);
  color: var(--color-error);
  background: var(--color-error-subtle);
}


/* ===== 9. RESULTS ===== */

.results-section {
  background: var(--color-result-bg);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  margin-top: var(--space-lg);
}

.results-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-md);
}

.results-header h2 {
  font-size: 1.1rem;
}

.results-actions {
  display: flex;
  gap: var(--space-sm);
}

.results-actions button {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  font-size: 12px;
  font-weight: 600;
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
  background: var(--color-bg-surface);
  border: 1px solid var(--color-border);
  transition: all var(--transition-fast);
}

.results-actions button:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
  background: var(--color-accent-subtle);
}

.results-actions button.copied {
  color: var(--color-success);
  border-color: var(--color-success);
  background: var(--color-success-subtle);
}

.results-grid {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: var(--space-md);
}

.result-group,
.result-card {
  background: var(--color-bg-surface);
  border-radius: var(--radius-md);
  padding: var(--space-lg) var(--space-md);
  text-align: center;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.result-group:first-child,
.result-card:first-child {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-md);
}

.result-group label,
.result-card label {
  display: block;
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-muted);
  margin-bottom: var(--space-sm);
}

.result-group input[readonly],
.result-card input[readonly] {
  font-family: var(--font-mono);
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--color-result-accent);
  border: none;
  background: transparent;
  text-align: center;
  width: 100%;
  padding: 0;
  outline: none;
}

.result-unit {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 500;
  color: var(--color-text-muted);
}

/* Result animation */
.result-group,
.result-card {
  opacity: 0;
  transform: translateY(12px);
}

.result-group.show-result,
.result-card.show-result,
.result-card.revealed {
  animation: resultReveal 0.4s ease-out forwards;
}
.result-group:nth-child(1).show-result,
.result-card:nth-child(1).show-result,
.result-card:nth-child(1).revealed { animation-delay: 0s; }
.result-group:nth-child(2).show-result,
.result-card:nth-child(2).show-result,
.result-card:nth-child(2).revealed { animation-delay: 0.1s; }
.result-group:nth-child(3).show-result,
.result-card:nth-child(3).show-result,
.result-card:nth-child(3).revealed { animation-delay: 0.2s; }

/* Timestamp */
.timestamp,
#calculationTimestamp {
  text-align: center;
  margin-top: var(--space-md);
  font-size: 12px;
  color: var(--color-text-muted);
}

/* Mobile close button for results */
.mobile-close-btn {
  display: none;
}


/* ===== 10. AUTH MODAL ===== */

.auth-overlay,
#directLoginOverlay {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--color-overlay);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  z-index: 1000;
  align-items: center;
  justify-content: center;
  padding: var(--space-lg);
}

.auth-overlay.active,
#directLoginOverlay.active {
  display: flex;
}

.auth-card {
  background: var(--color-bg-surface);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  width: 100%;
  max-width: 420px;
  box-shadow: var(--shadow-xl);
  border: 1px solid var(--color-border);
  position: relative;
}

.auth-card h2 {
  font-family: var(--font-heading);
  margin-bottom: var(--space-lg);
}

.auth-close {
  position: absolute;
  top: var(--space-md);
  right: var(--space-md);
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  color: var(--color-text-muted);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}
.auth-close:hover {
  background: var(--color-bg-elevated);
  color: var(--color-text-primary);
}

.auth-form-group {
  margin-bottom: var(--space-md);
}

.auth-form-group label {
  display: block;
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-muted);
  margin-bottom: 6px;
}

.auth-input {
  width: 100%;
  padding: 12px 16px;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-bg-elevated);
  color: var(--color-text-primary);
  font-size: 15px;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.auth-input:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-subtle);
  outline: none;
}

.auth-error {
  color: var(--color-error);
  font-size: 13px;
  margin-bottom: var(--space-sm);
  min-height: 20px;
}

.auth-success {
  color: var(--color-success);
  font-size: 13px;
  margin-bottom: var(--space-sm);
}

.auth-btn-row {
  display: flex;
  gap: var(--space-sm);
  margin-top: var(--space-lg);
}

.auth-btn-primary {
  flex: 1;
  padding: 12px;
  font-size: 15px;
  font-weight: 600;
  border-radius: var(--radius-sm);
  background: var(--color-accent);
  color: #fff;
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
}
.auth-btn-primary:hover {
  background: var(--color-accent-hover);
}

.auth-btn-secondary {
  flex: 1;
  padding: 12px;
  font-size: 15px;
  font-weight: 600;
  border-radius: var(--radius-sm);
  background: var(--color-bg-elevated);
  color: var(--color-text-secondary);
  border: 1.5px solid var(--color-border);
  cursor: pointer;
  transition: all var(--transition-fast);
}
.auth-btn-secondary:hover {
  border-color: var(--color-text-muted);
}

.auth-footer {
  margin-top: var(--space-md);
  font-size: 13px;
  color: var(--color-text-muted);
}

.auth-footer a {
  color: var(--color-accent);
  font-weight: 500;
}

.auth-forgot {
  text-align: right;
  margin-bottom: var(--space-md);
}

.auth-forgot a {
  font-size: 13px;
  color: var(--color-text-muted);
}
.auth-forgot a:hover {
  color: var(--color-accent);
}

/* Legacy modal support (loginModal) */
.modal {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--color-overlay);
  backdrop-filter: blur(6px);
  z-index: 1000;
  align-items: center;
  justify-content: center;
}

.modal-content {
  background: var(--color-bg-surface);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  width: 100%;
  max-width: 420px;
  box-shadow: var(--shadow-xl);
  border: 1px solid var(--color-border);
}

.modal .close-button {
  position: absolute;
  top: var(--space-md);
  right: var(--space-md);
  font-size: 24px;
  color: var(--color-text-muted);
  cursor: pointer;
}

.tab-container {
  display: flex;
  gap: 2px;
  margin-bottom: var(--space-lg);
  border-bottom: 2px solid var(--color-border);
}

.tab {
  flex: 1;
  padding: 10px;
  text-align: center;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text-muted);
  background: none;
  border: none;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  transition: all var(--transition-fast);
}

.tab.active {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.tab-content {
  display: none;
}
.tab-content.active {
  display: block;
}

.form-group {
  margin-bottom: var(--space-md);
}

.form-group label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--color-text-secondary);
  margin-bottom: 6px;
}

.form-group input {
  width: 100%;
  padding: 10px 14px;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-bg-elevated);
  color: var(--color-text-primary);
  transition: border-color var(--transition-fast);
}

.form-group input:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-subtle);
  outline: none;
}

.error-message {
  color: var(--color-error);
  font-size: 12px;
  min-height: 18px;
  margin-top: 4px;
}

.success-message {
  color: var(--color-success);
  font-size: 12px;
  margin-top: 4px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 20px;
  font-size: 15px;
  font-weight: 600;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  border: none;
  width: 100%;
}


/* ===== 11. FAQ ===== */

.faq-section {
  margin-top: var(--space-2xl);
  padding-top: var(--space-lg);
  border-top: 1px solid var(--color-border);
}

.faq-section > h2 {
  margin-bottom: var(--space-lg);
}

.faq-item {
  border-bottom: 1px solid var(--color-border);
}

.faq-item:first-child {
  border-top: 1px solid var(--color-border);
}

.faq-question {
  width: 100%;
  background: none;
  border: none;
  padding: var(--space-md) 0;
  text-align: left;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-md);
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: 500;
  color: var(--color-text-primary);
  transition: color var(--transition-fast);
}

.faq-question:hover {
  color: var(--color-accent);
}

.faq-question i {
  font-size: 14px;
  color: var(--color-text-muted);
  transition: transform var(--transition-base), color var(--transition-fast);
  flex-shrink: 0;
}

.faq-question.expanded i,
.faq-question.active i {
  transform: rotate(45deg);
  color: var(--color-accent);
}

.faq-answer {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows var(--transition-slow);
}

.faq-answer.expanded {
  grid-template-rows: 1fr;
}

.faq-answer-content,
.faq-answer > div {
  overflow: hidden;
}

.faq-answer-content p,
.faq-answer > div > p,
.faq-answer p {
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-text-secondary);
  padding-bottom: var(--space-md);
}


/* ===== 12. TRUST BAR ===== */

.trust-bar,
.security-badges {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-lg);
  padding: var(--space-lg) 0;
  margin-top: var(--space-lg);
}

.trust-badge,
.badge-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  font-weight: 500;
  color: var(--color-text-muted);
  letter-spacing: 0.02em;
}

.trust-badge i,
.badge-item i {
  color: var(--color-success);
  font-size: 14px;
}


/* ===== 13. FOOTER ===== */

.app-footer,
footer {
  text-align: center;
  padding: var(--space-lg) 0;
  border-top: 1px solid var(--color-border);
  margin-top: auto;
  font-size: 13px;
  color: var(--color-text-muted);
}

.app-footer a,
footer a {
  color: var(--color-accent);
}


/* ===== 14. TOAST / FEEDBACK ===== */

.toast {
  position: fixed;
  bottom: var(--space-lg);
  right: var(--space-lg);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 12px 20px;
  background: var(--color-bg-surface);
  color: var(--color-text-primary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  font-size: 14px;
  font-weight: 500;
  z-index: 2000;
  animation: toastSlideIn 0.3s ease-out;
}

.toast.hiding {
  animation: toastSlideOut 0.3s ease-in forwards;
}

.toast-icon {
  font-size: 16px;
}

.success-feedback {
  position: fixed;
  bottom: var(--space-lg);
  left: 50%;
  transform: translateX(-50%);
  padding: 12px 24px;
  background: var(--color-success);
  color: #fff;
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 600;
  z-index: 2000;
  animation: toastSlideIn 0.3s ease-out;
}

/* Loading animation */
.loading-animation,
#loadingAnimation {
  display: none;
  text-align: center;
  font-size: 2rem;
  padding: var(--space-md);
}

/* Loading spinner */
.spinner {
  width: 24px;
  height: 24px;
  border: 3px solid var(--color-border);
  border-top-color: var(--color-accent);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

.loading-overlay {
  position: absolute;
  inset: 0;
  background: var(--color-overlay);
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-lg);
  z-index: 10;
}


/* ===== 15. ANIMATIONS ===== */

@keyframes resultReveal {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes toastSlideIn {
  from {
    opacity: 0;
    transform: translateX(40px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes toastSlideOut {
  from {
    opacity: 1;
    transform: translateX(0);
  }
  to {
    opacity: 0;
    transform: translateX(40px);
  }
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}


/* ===== 16. RESPONSIVE: TABLET (768px) ===== */

@media (max-width: 768px) {
  .app-shell {
    padding: var(--space-md) var(--space-md) var(--space-xl);
  }

  .app-header {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-sm);
  }

  .header-actions {
    width: 100%;
    justify-content: space-between;
  }

  .subscription-toggle {
    display: flex;
  }

  .subscription-details {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-slow);
  }

  .subscription-details.expanded {
    max-height: 300px;
    margin-top: var(--space-sm);
  }

  .plan-banner {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-sm);
  }

  .plan-action {
    width: 100%;
  }

  .plan-action p {
    flex-wrap: wrap;
  }

  #calculatorContainer {
    padding: var(--space-lg);
  }

  .input-fields,
  .input-grid {
    grid-template-columns: 1fr 1fr;
  }

  .results-grid {
    grid-template-columns: 1fr 1fr 1fr;
    gap: var(--space-sm);
  }

  .result-group input[readonly],
  .result-card input[readonly] {
    font-size: 1.75rem;
  }
}


/* ===== 17. RESPONSIVE: MOBILE (480px) ===== */

@media (max-width: 480px) {
  h1 { font-size: 1.25rem; }

  .app-shell {
    padding: var(--space-sm) var(--space-sm) var(--space-lg);
  }

  #calculatorContainer {
    padding: var(--space-md);
    border-radius: var(--radius-md);
  }

  .input-fields,
  .input-grid {
    grid-template-columns: 1fr;
    gap: var(--space-sm);
  }

  .input-group input[type="number"] {
    font-size: 16px;
    padding: 14px 16px;
    min-height: 48px;
  }

  .button-section {
    flex-direction: row;
    gap: var(--space-sm);
  }

  .calculate-button,
  .reset-button {
    font-size: 15px;
    padding: 12px var(--space-md);
    min-height: 48px;
  }

  .results-grid {
    grid-template-columns: 1fr;
    gap: var(--space-sm);
  }

  .result-group,
  .result-card {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 18px;
    text-align: left;
  }

  .result-group label,
  .result-card label {
    margin-bottom: 0;
  }

  .result-group input[readonly],
  .result-card input[readonly] {
    font-size: 1.5rem;
    width: auto;
    text-align: right;
    flex-shrink: 0;
  }

  .results-section {
    padding: var(--space-md);
  }

  .results-header {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-sm);
  }

  .faq-question {
    font-size: 14px;
    padding: 14px 0;
  }

  .trust-bar,
  .security-badges {
    gap: var(--space-md);
  }

  .trust-badge,
  .badge-item {
    font-size: 11px;
  }

  .auth-card {
    padding: var(--space-lg);
    max-width: 100%;
    border-radius: var(--radius-md);
  }

  /* Toast on mobile */
  .toast {
    left: var(--space-md);
    right: var(--space-md);
    bottom: var(--space-md);
  }
}


/* ===== 18. RESPONSIVE: SMALL MOBILE (360px) ===== */

@media (max-width: 360px) {
  h1 { font-size: 1.1rem; }

  .header-tagline { font-size: 11px; }

  .account-chip .user-email { max-width: 120px; }

  .calculate-button,
  .reset-button {
    font-size: 14px;
    padding: 10px var(--space-sm);
  }
}


/* ===== 19. PRINT ===== */

@media print {
  .app-header,
  .subscription-strip,
  #subscriptionBanner,
  .subscription-toggle,
  .faq-section,
  .trust-bar,
  .security-badges,
  .app-footer,
  footer,
  .button-section,
  .expand-button,
  .results-actions,
  .toast,
  #directLoginOverlay,
  .auth-overlay,
  .modal {
    display: none;
  }

  body {
    background: #fff;
    color: #000;
  }

  #calculatorContainer {
    box-shadow: none;
    border: none;
    padding: 0;
  }

  .result-group input[readonly],
  .result-card input[readonly] {
    color: #000;
  }
}


/* ===== 20. UTILITY CLASSES ===== */

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Ensure initial result visibility before animation triggers */
.results-section .result-group,
.results-section .result-card {
  opacity: 1;
  transform: none;
}