/* ==========================================================================
   Market Research Survey — Premium SaaS Design System
   Inspired by Linear, Stripe, Notion, Typeform
   ========================================================================== */

/* --- CSS Custom Properties --- */
:root {
  /* Colors — Light theme */
  --color-bg: #fafafa;
  --color-bg-elevated: #ffffff;
  --color-bg-subtle: #f4f4f5;
  --color-border: #e4e4e7;
  --color-border-focus: #6366f1;
  --color-text: #18181b;
  --color-text-secondary: #71717a;
  --color-text-muted: #a1a1aa;
  --color-primary: #6366f1;
  --color-primary-hover: #4f46e5;
  --color-primary-subtle: rgba(99, 102, 241, 0.08);
  --color-primary-ring: rgba(99, 102, 241, 0.25);
  --color-success: #16a34a;
  --color-success-bg: rgba(22, 163, 74, 0.12);
  --color-error: #dc2626;
  --color-error-bg: rgba(220, 38, 38, 0.08);
  --color-warning: #d97706;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.06), 0 1px 3px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.08), 0 4px 12px rgba(0, 0, 0, 0.04);
  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.04), 0 0 0 1px var(--color-border);
  --shadow-card-hover: 0 8px 24px rgba(99, 102, 241, 0.12), 0 0 0 1px var(--color-primary);

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-arabic: 'Noto Sans Arabic', 'Inter', sans-serif;

  /* Spacing & sizing */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --header-height: 64px;
  --max-width: 640px;
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-spring: 400ms cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* Dark theme */
[data-theme="dark"] {
  --color-bg: #09090b;
  --color-bg-elevated: #18181b;
  --color-bg-subtle: #27272a;
  --color-border: #3f3f46;
  --color-border-focus: #818cf8;
  --color-text: #fafafa;
  --color-text-secondary: #a1a1aa;
  --color-text-muted: #71717a;
  --color-primary: #818cf8;
  --color-primary-hover: #6366f1;
  --color-primary-subtle: rgba(129, 140, 248, 0.12);
  --color-primary-ring: rgba(129, 140, 248, 0.3);
  --color-success: #22c55e;
  --color-success-bg: rgba(34, 197, 94, 0.15);
  --color-error: #ef4444;
  --color-error-bg: rgba(239, 68, 68, 0.12);
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.4);
  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.2), 0 0 0 1px var(--color-border);
  --shadow-card-hover: 0 8px 24px rgba(129, 140, 248, 0.15), 0 0 0 1px var(--color-primary);
}

/* --- Reset & Base --- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
  min-height: 100dvh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color var(--transition-base), color var(--transition-base);
}

/* Arabic typography */
html[lang="ar"] body,
html[lang="ar"] .survey-intro__text,
html[lang="ar"] .step__question,
html[lang="ar"] .option-card__label,
html[lang="ar"] .field-label,
html[lang="ar"] .consent-checkbox__text {
  font-family: var(--font-arabic);
}

/* RTL adjustments */
html[dir="rtl"] .header__brand,
html[dir="rtl"] .nav-buttons,
html[dir="rtl"] .header__controls {
  flex-direction: row-reverse;
}

html[dir="rtl"] .btn--primary svg {
  transform: scaleX(-1);
}

html[dir="rtl"] .progress-wrapper {
  flex-direction: row-reverse;
}

/* Confetti canvas */
#confetti-canvas {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 9999;
}

/* --- App Shell --- */
.app-shell {
  display: flex;
  flex-direction: column;
  min-height: 100dvh;
}

/* --- Header --- */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
  padding: 0 1.25rem;
  background: rgba(250, 250, 250, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  transition: background-color var(--transition-base), border-color var(--transition-base);
}

[data-theme="dark"] .header {
  background: rgba(9, 9, 11, 0.85);
}

.header__brand {
  display: flex;
  align-items: center;
  gap: 0.625rem;
}

.header__logo {
  color: var(--color-primary);
}

.header__title {
  font-size: 0.9375rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.header__controls {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Language switcher */
.lang-switcher {
  display: flex;
  background: var(--color-bg-subtle);
  border-radius: var(--radius-sm);
  padding: 3px;
  border: 1px solid var(--color-border);
}

.lang-btn {
  padding: 0.3125rem 0.625rem;
  font-size: 0.75rem;
  font-weight: 600;
  font-family: inherit;
  color: var(--color-text-secondary);
  background: transparent;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  transition: all var(--transition-fast);
  letter-spacing: 0.02em;
}

.lang-btn:hover {
  color: var(--color-text);
}

.lang-btn.active {
  background: var(--color-bg-elevated);
  color: var(--color-text);
  box-shadow: var(--shadow-sm);
}

.lang-btn:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* Theme toggle */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.theme-toggle:hover {
  color: var(--color-text);
  border-color: var(--color-text-muted);
}

.theme-toggle:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.icon-sun { display: block; }
.icon-moon { display: none; }

[data-theme="dark"] .icon-sun { display: none; }
[data-theme="dark"] .icon-moon { display: block; }

/* --- Main Content --- */
.main {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1.5rem 1.25rem 2rem;
}

.survey-container {
  width: 100%;
  max-width: var(--max-width);
  position: relative;
}

.survey-intro {
  margin-bottom: 1.75rem;
}

.survey-intro__text {
  font-size: clamp(1.125rem, 3.5vw, 1.375rem);
  font-weight: 600;
  line-height: 1.45;
  letter-spacing: -0.02em;
  color: var(--color-text);
  text-align: center;
  text-wrap: balance;
}

/* --- Progress --- */
.progress-wrapper {
  display: flex;
  align-items: center;
  gap: 0.875rem;
  margin-bottom: 2rem;
}

.progress-track {
  flex: 1;
  height: 4px;
  background: var(--color-bg-subtle);
  border-radius: 100px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--color-primary), #a78bfa);
  border-radius: 100px;
  transition: width var(--transition-spring);
}

.progress-text {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  white-space: nowrap;
  min-width: 3rem;
  text-align: end;
}

/* --- Steps --- */
.step {
  display: none;
  animation: none;
}

.step.active {
  display: block;
  animation: stepEnter var(--transition-spring) forwards;
}

.step.exit-left {
  animation: stepExitLeft var(--transition-base) forwards;
}

.step.enter-right {
  animation: stepEnterRight var(--transition-spring) forwards;
}

@keyframes stepEnter {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes stepExitLeft {
  from {
    opacity: 1;
    transform: translateX(0);
  }
  to {
    opacity: 0;
    transform: translateX(-24px);
  }
}

@keyframes stepEnterRight {
  from {
    opacity: 0;
    transform: translateX(24px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.step__question {
  font-size: clamp(1.375rem, 4vw, 1.75rem);
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 1.3;
  margin-bottom: 0.75rem;
  color: var(--color-text);
}

.step__hint {
  font-size: 0.9375rem;
  color: var(--color-text-secondary);
  margin-bottom: 1.5rem;
}

/* --- Option Cards --- */
.card-grid {
  display: grid;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.card-grid--single {
  grid-template-columns: 1fr;
}

@media (min-width: 480px) {
  .card-grid:not(.card-grid--compact) {
    grid-template-columns: repeat(2, 1fr);
  }
}

.option-card {
  position: relative;
  cursor: pointer;
}

.option-card input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.option-card__inner {
  display: flex;
  align-items: center;
  gap: 0.875rem;
  padding: 1rem 1.125rem;
  background: var(--color-bg-elevated);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
  user-select: none;
}

.option-card:hover .option-card__inner {
  border-color: var(--color-text-muted);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.option-card input:focus-visible + .option-card__inner {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.option-card input:checked + .option-card__inner {
  border-color: var(--color-primary);
  background: var(--color-primary-subtle);
  box-shadow: var(--shadow-card-hover);
}

.option-card.is-invalid .option-card__inner {
  border-color: var(--color-error);
  background: var(--color-error-bg);
}

.option-card__icon {
  font-size: 1.375rem;
  line-height: 1;
  flex-shrink: 0;
}

.option-card__label {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--color-text);
}

.card-grid--compact .option-card__inner {
  justify-content: center;
  padding: 0.875rem 1rem;
}

/* Checkbox indicator for multi-select */
.option-card--checkbox input:checked + .option-card__inner::after {
  content: '✓';
  position: absolute;
  top: 0.625rem;
  inset-inline-end: 0.625rem;
  width: 20px;
  height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-primary);
  color: white;
  font-size: 0.6875rem;
  font-weight: 700;
  border-radius: 50%;
}

.option-card--checkbox .option-card__inner {
  position: relative;
}

/* --- Form Fields --- */
.field-group {
  margin-bottom: 1rem;
}

.field-group--conditional {
  margin-top: 1.25rem;
  animation: stepEnter var(--transition-spring) forwards;
}

.field-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: 0.5rem;
}

.field-label__optional {
  font-weight: 400;
  color: var(--color-text-muted);
  font-size: 0.8125rem;
}

.input,
.textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  font-size: 0.9375rem;
  font-family: inherit;
  color: var(--color-text);
  background: var(--color-bg-elevated);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  resize: vertical;
}

.input:hover,
.textarea:hover {
  border-color: var(--color-text-muted);
}

.input:focus,
.textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-ring);
}

.input.is-invalid,
.textarea.is-invalid {
  border-color: var(--color-error);
  background: var(--color-error-bg);
}

.form-fields {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

/* Consent checkbox */
.consent-checkbox {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  margin-top: 1rem;
  padding: 1rem;
  background: var(--color-bg-subtle);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  cursor: pointer;
  transition: border-color var(--transition-fast);
}

.consent-checkbox:hover {
  border-color: var(--color-text-muted);
}

.consent-checkbox input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.consent-checkbox__box {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  margin-top: 2px;
  border: 1.5px solid var(--color-border);
  border-radius: 5px;
  background: var(--color-bg-elevated);
  transition: all var(--transition-fast);
  position: relative;
}

.consent-checkbox input:checked + .consent-checkbox__box {
  background: var(--color-primary);
  border-color: var(--color-primary);
}

.consent-checkbox input:checked + .consent-checkbox__box::after {
  content: '✓';
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 0.75rem;
  font-weight: 700;
}

.consent-checkbox input:focus-visible + .consent-checkbox__box {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.consent-checkbox.is-invalid {
  border-color: var(--color-error);
  background: var(--color-error-bg);
}

.consent-checkbox__text {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

/* --- Validation --- */
.validation-msg {
  font-size: 0.8125rem;
  color: var(--color-error);
  min-height: 1.25rem;
  margin-top: 0.5rem;
  opacity: 0;
  transform: translateY(-4px);
  transition: all var(--transition-fast);
}

.validation-msg.visible {
  opacity: 1;
  transform: translateY(0);
}

/* --- Navigation Buttons --- */
.nav-buttons {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-top: 2rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--color-border);
}

.nav-buttons__actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-inline-start: auto;
}

.nav-buttons__actions .btn--primary {
  margin-inline-start: 0;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  font-size: 0.9375rem;
  font-weight: 600;
  font-family: inherit;
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.btn:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.btn--primary {
  background: var(--color-primary);
  color: white;
  box-shadow: 0 1px 2px rgba(99, 102, 241, 0.3), 0 4px 12px rgba(99, 102, 241, 0.2);
  margin-inline-start: auto;
}

.btn--primary:hover:not(:disabled) {
  background: var(--color-primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 2px 4px rgba(99, 102, 241, 0.3), 0 8px 20px rgba(99, 102, 241, 0.25);
}

.btn--primary:active:not(:disabled) {
  transform: translateY(0);
}

.btn--primary:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

.btn--ghost {
  background: transparent;
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
}

.btn--ghost:hover {
  color: var(--color-text);
  background: var(--color-bg-subtle);
  border-color: var(--color-text-muted);
}

/* Submit button loading state */
.btn--loading .btn__text {
  opacity: 0;
}

.btn--loading .btn__loader {
  display: block;
}

.btn__loader {
  display: none;
  position: absolute;
  width: 18px;
  height: 18px;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-top-color: white;
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

#btn-submit {
  position: relative;
}

#btn-next[hidden],
#btn-skip[hidden],
#btn-submit[hidden] {
  display: none !important;
}

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

/* --- Success State --- */
.success-state,
.error-state {
  text-align: center;
  padding: 3rem 1.5rem;
  animation: stepEnter var(--transition-spring) forwards;
}

.success-state__icon,
.error-state__icon {
  margin-bottom: 1.5rem;
  animation: successPop 600ms cubic-bezier(0.34, 1.56, 0.64, 1) 200ms both;
}

@keyframes successPop {
  from {
    opacity: 0;
    transform: scale(0.5);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

.success-state__title,
.error-state__title {
  font-size: clamp(1.5rem, 4vw, 1.875rem);
  font-weight: 700;
  letter-spacing: -0.025em;
  margin-bottom: 0.75rem;
}

.success-state__subtitle {
  font-size: 1rem;
  color: var(--color-text-secondary);
  margin-bottom: 2rem;
  max-width: 400px;
  margin-inline: auto;
}

.error-state__message {
  font-size: 1rem;
  color: var(--color-text-secondary);
  margin-bottom: 2rem;
}

.error-state__icon {
  font-size: 3rem;
}

/* --- Footer --- */
.footer {
  margin-top: auto;
  padding-top: 2rem;
  text-align: center;
}

.footer p {
  font-size: 0.8125rem;
  color: var(--color-text-muted);
}

/* --- Utilities --- */
.hidden {
  display: none !important;
}

/* --- Responsive --- */
@media (max-width: 479px) {
  .header {
    padding: 0 1rem;
  }

  .header__title {
    display: none;
  }

  .nav-buttons {
    flex-wrap: wrap;
  }

  .nav-buttons__actions {
    flex: 1;
    flex-wrap: wrap;
    justify-content: flex-end;
  }

  .nav-buttons__actions .btn--primary {
    flex: 1;
    min-width: 0;
  }

  .btn--ghost {
    flex: 0 0 auto;
  }
}

@media (min-width: 768px) {
  .main {
    padding: 2.5rem 2rem 3rem;
  }

  .progress-wrapper {
    margin-bottom: 2.5rem;
  }
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  html {
    scroll-behavior: auto;
  }
}