/* ==========================================================================
   DocDoe AI — Frontend Polish & Production Excellence
   Premium interaction layer for Apple-level UX
   ========================================================================== */

/* ══════════════════════════════════════════════════════════════════════════
   1. TOUCH RESPONSIVENESS
   Eliminate 300ms tap delay, optimize touch targets, ensure mobile-first feel
   ══════════════════════════════════════════════════════════════════════════ */

/* Universal touch optimization - apply to ALL interactive elements */
button,
a[href],
input[type="button"],
input[type="submit"],
input[type="reset"],
[role="button"],
[role="link"],
[tabindex]:focus,
label,
summary,
-details > summary {
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  -webkit-user-select: none;
  user-select: none;
}

/* Keep 44px touch targets on compact screens without overriding deliberate
   desktop control sizes or every Tailwind padding utility in the product. */
@media (max-width: 768px) and (hover: none) {
  button,
  [role="button"],
  [role="tab"],
  a[href] {
    min-height: 44px;
    min-width: 44px;
  }
}

/* ══════════════════════════════════════════════════════════════════════════
   2. ACTIVE & HOVER STATES
   Consistent, immediate feedback for all interactive elements
   ══════════════════════════════════════════════════════════════════════════ */

/* Base transition for all interactive elements - fast and smooth */
button,
a[href],
[role="button"],
input[type="button"],
input[type="submit"],
input[type="reset"],
[role="tab"] {
  transition:
    background-color 0.15s var(--ease-out),
    border-color 0.15s var(--ease-out),
    color 0.15s var(--ease-out),
    transform 0.1s var(--ease-out),
    box-shadow 0.15s var(--ease-out),
    opacity 0.15s var(--ease-out);
  will-change: transform, opacity;
}

/* Active state - subtle scale for physical feel (98% for press) */
button:active:not(:disabled),
[role="button"]:active:not(:disabled),
a[href]:active,
input[type="button"]:active:not(:disabled),
input[type="submit"]:active:not(:disabled),
input[type="reset"]:active:not(:disabled),
[role="tab"]:active:not(:disabled) {
  transform: scale(0.98);
}

/* Hover state - elevate slightly for premium feel */
button:hover:not(:disabled):not(:active),
[role="button"]:hover:not(:disabled):not(:active),
a[href]:hover:not(:disabled):not(:active),
input[type="button"]:hover:not(:disabled):not(:active),
input[type="submit"]:hover:not(:disabled):not(:active),
input[type="reset"]:hover:not(:disabled):not(:active),
[role="tab"]:hover:not(:disabled):not(:active) {
  transform: translateY(-1px);
}

/* Focus visible - consistent focus ring for accessibility */
button:focus-visible,
a[href]:focus-visible,
[role="button"]:focus-visible,
input:focus-visible,
[role="tab"]:focus-visible {
  outline: none;
  box-shadow:
    0 0 0 3px rgba(255, 255, 255, 0.12),
    0 0 0 1px rgba(255, 255, 255, 0.28);
}

/* Disabled state - clear and consistent */
button:disabled,
[role="button"]:disabled,
input:disabled,
[role="tab"]:disabled {
  cursor: not-allowed;
  opacity: 0.4;
  transform: none !important;
}

/* ══════════════════════════════════════════════════════════════════════════
   3. TAP FEEDBACK FOR TOUCH DEVICES
   Instant visual confirmation on touch
   ══════════════════════════════════════════════════════════════════════════ */

/* Tap highlight for touch devices */
@media (hover: none) {
  button:active:not(:disabled),
  [role="button"]:active:not(:disabled),
  a[href]:active {
    background: rgba(255, 255, 255, 0.08) !important;
    transform: scale(0.96) !important;
  }
}

/* Touch ripple effect for primary actions */
.touch-ripple {
  position: relative;
  overflow: hidden;
}

.touch-ripple::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  background: rgba(255, 255, 255, 0.15);
  border-radius: 50%;
  transform: translate(-50%, -50%);
  opacity: 0;
  transition:
    width 0.3s ease,
    height 0.3s ease,
    opacity 0.3s ease;
  pointer-events: none;
}

.touch-ripple:active::after {
  width: 200%;
  height: 200%;
  opacity: 1;
}

/* ══════════════════════════════════════════════════════════════════════════
   4. LOADING STATES
   Smooth, skeleton-based loading for content
   ══════════════════════════════════════════════════════════════════════════ */

/* Loading skeleton base */
.skeleton {
  background: linear-gradient(
    90deg,
    var(--bg-elevated) 25%,
    var(--bg-glass) 50%,
    var(--bg-elevated) 75%
  );
  background-size: 200% 100%;
  animation: skeleton-loading 1.5s infinite;
  border-radius: var(--radius-sm);
}

@keyframes skeleton-loading {
  0% {
    background-position: 200% 0;
  }
  100% {
    background-position: -200% 0;
  }
}

/* Text skeleton */
.skeleton-text {
  height: 1em;
  margin-bottom: 0.5em;
}

.skeleton-text.short {
  width: 60%;
}
.skeleton-text.medium {
  width: 80%;
}

/* Card skeleton */
.skeleton-card {
  height: 120px;
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
}

/* Button skeleton */
.skeleton-button {
  height: 44px;
  width: 120px;
  border-radius: var(--radius-sm);
}

/* Spinner - consistent across app */
.spinner {
  width: 20px;
  height: 20px;
  border: 2px solid transparent;
  border-top-color: currentColor;
  border-radius: 50%;
  animation: spinner-rotate 0.8s linear infinite;
  display: inline-block;
}

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

/* Loading overlay for containers */
.loading-overlay {
  position: relative;
}

.loading-overlay::after {
  content: "";
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  backdrop-filter: blur(4px);
  border-radius: inherit;
  display: flex;
  align-items: center;
  justify-content: center;
}

.loading-overlay::before {
  content: "";
  position: absolute;
  inset: 0;
  background: inherit;
  border-radius: inherit;
  z-index: -1;
}

/* ══════════════════════════════════════════════════════════════════════════
   5. SCROLL OPTIMIZATION
   Smooth, jank-free scrolling
   ══════════════════════════════════════════════════════════════════════════ */

/* Smooth scrolling globally */
html {
  scroll-behavior: smooth;
}

/* Scroll container optimization */
* {
  scrollbar-width: thin;
  scrollbar-color: rgba(255, 255, 255, 0.12) transparent;
}

/* Hide scrollbar on mobile for cleaner look */
@media (max-width: 768px) {
  *::-webkit-scrollbar {
    display: none;
  }
  * {
    scrollbar-width: none;
  }
}

/* Scrollbar styling for desktop */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.12);
  border-radius: 3px;
  border: 2px solid transparent;
  background-clip: content-box;
}

::-webkit-scrollbar-thumb:hover {
  background: rgba(255, 255, 255, 0.22);
}

/* Prevent scroll jank with contain */
offscreen,
[content-visibility="auto"] {
  contain-intrinsic-size: auto 1000px;
}

/* ══════════════════════════════════════════════════════════════════════════
   6. MOBILE-SPECIFIC OPTIMIZATIONS
   Thumb-friendly, compact, efficient
   ══════════════════════════════════════════════════════════════════════════ */

/* Mobile touch targets - ensure minimum 44px */
@media (max-width: 768px) {
  button,
  [role="button"],
  a[href],
  [role="tab"],
  .touch-target {
    min-height: 44px;
    min-width: 44px;
  }

  /* Larger touch targets for primary actions */
  .btn-primary,
  .btn-hero,
  .btn-secondary {
    min-height: 48px;
  }
}

/* Mobile card interactions - larger tap area */
@media (max-width: 768px) {
  .card-touch-area {
    padding: 4px;
    margin: -4px;
    border-radius: inherit;
  }

  /* Mobile card active state */
  .card-touch-area:active {
    transform: scale(0.97);
    opacity: 0.8;
  }
}

/* Mobile form inputs - larger tap areas */
@media (max-width: 768px) {
  input,
  textarea,
  select {
    min-height: 48px;
  }

  input[type="checkbox"],
  input[type="radio"] {
    min-width: 44px;
    min-height: 44px;
  }
}

/* ══════════════════════════════════════════════════════════════════════════
   7. BLUR OPTIMIZATION
   Reduce expensive backdrop-filter on mobile
   ══════════════════════════════════════════════════════════════════════════ */

/* Disable expensive blur on low-end devices */
@media (max-width: 768px) and (hover: none) {
  *,
  *::before,
  *::after {
    backdrop-filter: none !important;
    -webkit-backdrop-filter: none !important;
  }

  /* Keep each component's own light or dark surface. A blanket dark
     replacement made light navigation, lesson headers, and sticky actions
     turn black on touch devices. The existing alpha background remains a
     sufficient low-cost fallback after blur is disabled above. */
}

/* Reduced blur for performance */
@media (forced-colors: active) {
  *,
  *::before,
  *::after {
    backdrop-filter: none !important;
    -webkit-backdrop-filter: none !important;
  }
}

/* ══════════════════════════════════════════════════════════════════════════
   8. ANIMATION PERFORMANCE
   Optimized for low-end Android devices
   ══════════════════════════════════════════════════════════════════════════ */

/* Hardware acceleration for animations */
.gpu-accel {
  transform: translateZ(0);
  will-change: transform, opacity;
  backface-visibility: hidden;
  perspective: 1000px;
}

/* Optimized animations - no heavy effects */
@keyframes fade-in-fast {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

@keyframes slide-up-fast {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.animate-fade-in-fast {
  animation: fade-in-fast 0.15s var(--ease-out) both;
}
.animate-slide-up-fast {
  animation: slide-up-fast 0.2s var(--ease-out) both;
}

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

/* ══════════════════════════════════════════════════════════════════════════
   9. EMPTY STATES
   Clean, helpful empty states
   ══════════════════════════════════════════════════════════════════════════ */

.empty-state {
  text-align: center;
  padding: 48px 24px;
}

.empty-state-icon {
  width: 64px;
  height: 64px;
  margin: 0 auto 16px;
  background: var(--bg-elevated);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
}

.empty-state-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.empty-state-description {
  font-size: 14px;
  color: var(--text-secondary);
  max-width: 300px;
  margin: 0 auto;
}

.empty-state-actions {
  margin-top: 24px;
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ══════════════════════════════════════════════════════════════════════════
   10. CARD INTERACTIONS
   Premium feel for all card components
   ══════════════════════════════════════════════════════════════════════════ */

/* Card hover - subtle elevation */
.card-hover {
  border: 1px solid var(--border-subtle);
  transition:
    border-color 0.15s var(--ease-out),
    box-shadow 0.2s var(--ease-out),
    transform 0.1s var(--ease-out);
}

.card-hover:hover {
  border-color: var(--border-medium);
  box-shadow: var(--shadow-sm);
}

/* Card active - press effect */
.card-hover:active {
  transform: scale(0.99);
}

/* Premium card - glass effect with fallback */
.premium-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  transition:
    background-color 0.2s var(--ease-out),
    border-color 0.15s var(--ease-out),
    box-shadow 0.2s var(--ease-out);
}

.premium-card:hover {
  background: var(--bg-elevated);
  border-color: var(--border-medium);
  box-shadow: var(--shadow-md);
}

/* ══════════════════════════════════════════════════════════════════════════
   11. FORM ELEMENTS
   Clean, accessible form controls
   ══════════════════════════════════════════════════════════════════════════ */

/* Global: kill all native focus styles on form elements.
   Visual feedback is handled per-component (outer focus-within glow). */
input:focus,
textarea:focus,
select:focus {
  outline: none;
  box-shadow: none;
}

/* Explicit form inputs (login, settings, onboarding) keep their own focus ring */
.input-field:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(245, 158, 11, 0.08);
}

/* Input hover state */
input:hover:not(:focus),
textarea:hover:not(:focus),
select:hover:not(:focus) {
  border-color: var(--border-medium);
}

/* Input disabled state */
input:disabled,
textarea:disabled,
select:disabled {
  background: var(--bg-glass);
  border-color: var(--border-subtle);
  color: var(--text-muted);
  cursor: not-allowed;
}

/* Input error state */
input.error,
textarea.error,
select.error {
  border-color: var(--accent-red);
  background: rgba(251, 113, 133, 0.05);
}

input.error:focus,
textarea.error:focus,
select.error:focus {
  box-shadow: 0 0 0 3px rgba(251, 113, 133, 0.15);
}

/* Label interactions */
label {
  cursor: pointer;
  transition: color 0.15s var(--ease-out);
}

label:hover {
  color: var(--text-primary);
}

/* ══════════════════════════════════════════════════════════════════════════
   12. NAVIGATION
   Smooth, confident navigation
   ══════════════════════════════════════════════════════════════════════════ */

/* Link transitions */
a {
  transition: color 0.15s var(--ease-out);
}

/* Nav item active state */
.nav-item {
  position: relative;
  transition:
    color 0.15s var(--ease-out),
    background-color 0.15s var(--ease-out);
}

.nav-item:active {
  transform: scale(0.97);
}

/* Nav underline indicator */
.nav-underline {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--accent-primary);
  border-radius: 1px;
  transform: scaleX(0);
  transition: transform 0.2s var(--ease-out);
}

.nav-item.active .nav-underline {
  transform: scaleX(1);
}

/* ══════════════════════════════════════════════════════════════════════════
   13. HYDRATION
   Prevent layout shift and flicker
   ══════════════════════════════════════════════════════════════════════════ */

/* Prevent layout shift on hydration */
input.caret-transparent,
input.caret-transparent:focus {
  caret-color: transparent;
}
.hydrate-safe {
  contain-intrinsic-size: auto 1000px;
  content-visibility: auto;
}

/* Skeleton during loading */
[aria-busy="true"] {
  position: relative;
}

[aria-busy="true"]::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(
    90deg,
    transparent 0%,
    rgba(255, 255, 255, 0.04) 50%,
    transparent 100%
  );
  background-size: 200% 100%;
  animation: skeleton-loading 1.5s infinite;
  border-radius: inherit;
  pointer-events: none;
}

/* Hide content until hydrated */
[aria-live="polite"] {
  opacity: 1;
  transition: opacity 0.2s var(--ease-out);
}

/* ══════════════════════════════════════════════════════════════════════════
   14. BUTTON VARIANTS
   Consistent button styles
   ══════════════════════════════════════════════════════════════════════════ */

/* Primary button - consistent style */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: -0.01em;
  transition:
    background-color 0.15s var(--ease-out),
    border-color 0.15s var(--ease-out),
    color 0.15s var(--ease-out),
    transform 0.1s var(--ease-out);
  min-height: 44px;
  touch-action: manipulation;
}

/* DocDoe primary action = white on near-black, matching the signup and
   composer-send buttons. The old amber (#F59E0B) fought the monochrome brand. */
.btn-primary {
  background: #ffffff;
  color: #080808;
  border: 1px solid rgba(255, 255, 255, 0.16);
}

.btn-primary:hover:not(:disabled) {
  background: rgba(255, 255, 255, 0.9);
}

.btn-primary:active:not(:disabled) {
  transform: scale(0.98);
}

.btn-secondary {
  background: var(--bg-surface);
  color: var(--text-primary);
  border: 1px solid var(--border-medium);
}

.btn-secondary:hover:not(:disabled) {
  background: var(--bg-elevated);
  border-color: var(--border-medium);
}

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

.btn-ghost:hover:not(:disabled) {
  background: var(--bg-glass);
  border-color: var(--border-medium);
  color: var(--text-primary);
}

.btn-disabled {
  cursor: not-allowed;
  opacity: 0.4;
  transform: none !important;
}

/* ══════════════════════════════════════════════════════════════════════════
   15. TYPOGRAPHY REFINEMENTS
   Better readability and hierarchy
   ══════════════════════════════════════════════════════════════════════════ */

/* Text balancing for headings */
h1,
h2,
h3,
h4,
h5,
h6 {
  text-wrap: balance;
}

/* Line height adjustments */
p {
  line-height: 1.6;
}

/* Selection styling — mono, matching the black/white identity (no legacy amber) */
::selection {
  background: rgba(255, 255, 255, 0.18);
  color: var(--text-primary);
}

/* Focus visible for all elements */
*:focus-visible {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

/* Remove default focus outline when using mouse */
*:focus:not(:focus-visible) {
  outline: none;
}

/* ══════════════════════════════════════════════════════════════════════════
   16. Z-INDEX MANAGEMENT
   Consistent layering
   ══════════════════════════════════════════════════════════════════════════ */

/* Base z-index scale */
.z-dropdown {
  z-index: 100;
}
.z-sticky {
  z-index: 200;
}
.z-fixed {
  z-index: 300;
}
.z-modal-backdrop {
  z-index: 400;
}
.z-modal {
  z-index: 500;
}
.z-popover {
  z-index: 600;
}
.z-tooltip {
  z-index: 700;
}

/* ══════════════════════════════════════════════════════════════════════════
   17. FORBIDDEN WORDS REPLACEMENT
   Replace technical terms with student-friendly language
   ══════════════════════════════════════════════════════════════════════════ */

/* Hide raw technical error messages */
.error-message {
  color: var(--accent-red);
  font-size: 14px;
}

/* User-friendly error states */
.error-friendly {
  color: var(--text-secondary);
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  padding: 12px 16px;
  border-radius: var(--radius-sm);
}

/* Loading messages */
.loading-message {
  color: var(--text-secondary);
}

/* Success states */
.success-message {
  color: var(--accent-emerald);
  background: rgba(16, 185, 129, 0.05);
  border: 1px solid rgba(16, 185, 129, 0.2);
  padding: 12px 16px;
  border-radius: var(--radius-sm);
}

/* ══════════════════════════════════════════════════════════════════════════
   18. RESPONSIVE TYPE SCALE
   Better mobile typography
   ══════════════════════════════════════════════════════════════════════════ */

@media (max-width: 768px) {
  html {
    font-size: 15px;
  }

  /* Better mobile touch targets */
  .mobile-touch {
    min-height: 48px;
    padding: 12px 16px;
  }
}

/*
 * Mobile type defaults live in the base layer so any Tailwind utility on the
 * element wins. Unlayered, these element selectors silently beat every
 * text-* class on phones (cascade layers: unlayered > layered), flattening
 * all heading hierarchy across the whole app.
 */
@layer base {
  @media (max-width: 768px) {
    h1 {
      font-size: 28px;
    }
    h2 {
      font-size: 24px;
    }
    h3 {
      font-size: 20px;
    }

    p,
    li {
      font-size: 15px;
      line-height: 1.5;
    }
  }
}

/* ══════════════════════════════════════════════════════════════════════════
   19. SAFE AREA INSETS
   Proper mobile viewport handling
   ══════════════════════════════════════════════════════════════════════════ */

/* Safe areas are applied on fixed chrome (bottom nav, drawers, composers).
   Do not pad the whole body — that fights fixed footers and double-counts
   insets on iOS. */

/* Full viewport height handling */
.min-h-svh {
  min-height: 100svh;
}

.min-h-dvh {
  min-height: 100dvh;
}

/* Mobile bottom navigation */
.mobile-nav {
  padding-bottom: calc(env(safe-area-inset-bottom) + 16px);
}

/* ══════════════════════════════════════════════════════════════════════════
   20. PRINT STYLES
   Clean printing for study materials
   ══════════════════════════════════════════════════════════════════════════ */

@media print {
  .no-print {
    display: none !important;
  }

  body {
    background: white;
    color: black;
  }

  .workspace-card,
  .premium-panel,
  .glass-panel {
    background: white;
    border: 1px solid #e5e7eb;
    box-shadow: none;
  }
}

/* ══════════════════════════════════════════════════════════════════════════
   StudyCast / Discuss player — transcript scroller polish
   Dedicated thin, high-quality scrollbar for the live highlighted transcript
   in the floating premium player (current things perfection).
   ══════════════════════════════════════════════════════════════════════════ */
.custom-scroll {
  scrollbar-width: thin;
  scrollbar-color: rgba(255, 255, 255, 0.18) transparent;
}

.custom-scroll::-webkit-scrollbar {
  width: 5px;
}

.custom-scroll::-webkit-scrollbar-track {
  background: transparent;
}

.custom-scroll::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.15);
  border-radius: 4px;
}

.custom-scroll::-webkit-scrollbar-thumb:hover {
  background: rgba(255, 255, 255, 0.28);
}