/* =========================================================================
   Cutout — AI Background Remover
   Design tokens + component styles.
   Signature motif: the transparency checkerboard (the universal symbol for
   "no background") is used as a real, functional texture throughout —
   in the upload card, the result stage, and the ambient blobs — rather
   than a decorative gradient.
   ========================================================================= */

:root {
  /* Color tokens — light theme */
  --bg: #F7F7F8;
  --bg-elevated: #FFFFFF;
  --ink: #0B0B0E;
  --ink-soft: #52525B;
  --border: rgba(11, 11, 14, 0.08);
  --glass-bg: rgba(255, 255, 255, 0.6);
  --glass-border: rgba(255, 255, 255, 0.5);
  --shadow-color: 220 20% 40%;

  --accent-1: #5B5FEF;   /* indigo */
  --accent-2: #22D3EE;   /* cyan */
  --accent-3: #34D8A0;   /* mint / success */
  --accent-grad: linear-gradient(135deg, var(--accent-1), var(--accent-2));

  --checker-a: rgba(11, 11, 14, 0.06);
  --checker-b: transparent;
  --checker-size: 20px;

  --radius-lg: 24px;
  --radius-md: 16px;
  --radius-sm: 10px;

  --ease: cubic-bezier(0.16, 1, 0.3, 1);
  --dur-fast: 150ms;
  --dur-base: 220ms;
}

[data-theme="dark"] {
  --bg: #08090B;
  --bg-elevated: #101114;
  --ink: #F5F5F7;
  --ink-soft: #A1A1AA;
  --border: rgba(255, 255, 255, 0.08);
  --glass-bg: rgba(20, 21, 26, 0.55);
  --glass-border: rgba(255, 255, 255, 0.08);

  --checker-a: rgba(255, 255, 255, 0.07);
  --checker-b: transparent;
}

/* =========================================================================
   Reset & base
   ========================================================================= */

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: 'Inter', sans-serif;
  transition: background var(--dur-base) var(--ease), color var(--dur-base) var(--ease);
  overflow-x: hidden;
}

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

:focus-visible {
  outline: 2px solid var(--accent-1);
  outline-offset: 3px;
  border-radius: 6px;
}

button {
  font-family: inherit;
  cursor: pointer;
}

/* =========================================================================
   Ambient background — soft gradient blobs with a checkerboard fringe
   ========================================================================= */

.ambient {
  position: fixed;
  inset: 0;
  z-index: 0;
  overflow: hidden;
  pointer-events: none;
}

.blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(70px);
  opacity: 0.35;
  will-change: transform;
}

.blob--a {
  width: 46vw;
  height: 46vw;
  top: -14vw;
  left: -10vw;
  background: var(--accent-grad);
}

.blob--b {
  width: 36vw;
  height: 36vw;
  bottom: -12vw;
  right: -8vw;
  background: linear-gradient(135deg, var(--accent-3), var(--accent-1));
  opacity: 0.25;
}

.grain {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(45deg, var(--checker-a) 25%, var(--checker-b) 25%, var(--checker-b) 75%, var(--checker-a) 75%),
    linear-gradient(45deg, var(--checker-a) 25%, var(--checker-b) 25%, var(--checker-b) 75%, var(--checker-a) 75%);
  background-size: 64px 64px;
  background-position: 0 0, 32px 32px;
  opacity: 0.4;
  mask-image: radial-gradient(circle at 20% 10%, black, transparent 55%);
}

/* =========================================================================
   Glassmorphism utility
   ========================================================================= */

.glass {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  backdrop-filter: blur(20px) saturate(140%);
  -webkit-backdrop-filter: blur(20px) saturate(140%);
  box-shadow:
    0 1px 1px hsl(var(--shadow-color) / 0.03),
    0 8px 24px -8px hsl(var(--shadow-color) / 0.18),
    0 24px 48px -24px hsl(var(--shadow-color) / 0.22);
}

/* =========================================================================
   Navbar
   ========================================================================= */

.navbar {
  position: sticky;
  top: 0;
  z-index: 40;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  background: color-mix(in srgb, var(--bg) 72%, transparent);
  border-bottom: 1px solid var(--border);
}

.navbar__inner {
  max-width: 1180px;
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--ink);
}

.logo__tile {
  fill: url(#logoGradientFallback);
  fill: var(--accent-1);
}

.logo__mark svg rect {
  fill: var(--accent-1);
}

.logo__text {
  font-family: 'Sora', sans-serif;
  font-weight: 700;
  font-size: 1.15rem;
  letter-spacing: -0.02em;
}

.navbar__actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.icon-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  height: 40px;
  padding: 0 14px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  color: var(--ink);
  font-size: 0.85rem;
  font-weight: 500;
  transition: transform var(--dur-fast) var(--ease), border-color var(--dur-fast) var(--ease), background var(--dur-fast) var(--ease);
}

.icon-btn:hover {
  transform: translateY(-1px);
  border-color: var(--accent-1);
}

.icon-btn:active {
  transform: translateY(0px) scale(0.97);
}

.icon-btn--github span {
  display: none;
}

@media (min-width: 640px) {
  .icon-btn--github span {
    display: inline;
  }
}

.icon-btn--sm {
  width: 32px;
  height: 32px;
  padding: 0;
  justify-content: center;
  border-radius: 50%;
  font-size: 1.1rem;
  line-height: 1;
}

#themeToggle {
  width: 40px;
  justify-content: center;
  padding: 0;
}

.icon {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
}

.icon-btn--github .icon {
  width: 17px;
  height: 17px;
}

.icon--moon {
  display: none;
}

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

[data-theme="dark"] .icon--moon {
  display: block;
}

/* =========================================================================
   Hero
   ========================================================================= */

.hero {
  position: relative;
  z-index: 1;
  padding: 96px 24px 64px;
}

.hero__inner {
  max-width: 780px;
  margin: 0 auto;
  text-align: center;
}

.eyebrow {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.78rem;
  letter-spacing: 0.02em;
  color: var(--ink-soft);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  display: inline-block;
  padding: 6px 14px;
  border-radius: 999px;
  margin-bottom: 28px;
}

.hero__headline {
  font-family: 'Sora', sans-serif;
  font-weight: 700;
  font-size: clamp(2.4rem, 6vw, 4rem);
  line-height: 1.06;
  letter-spacing: -0.03em;
  margin: 0 0 20px;
}

.hero__headline-accent {
  background: var(--accent-grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero__subtitle {
  font-size: 1.05rem;
  color: var(--ink-soft);
  margin: 0 0 44px;
}

/* =========================================================================
   Upload card
   ========================================================================= */

.upload-card {
  border-radius: var(--radius-lg);
  padding: 12px;
  max-width: 640px;
  margin: 0 auto;
}

.drop-zone {
  position: relative;
  border: 1.5px dashed var(--border);
  border-radius: calc(var(--radius-lg) - 8px);
  padding: 56px 32px;
  overflow: hidden;
  transition: border-color var(--dur-base) var(--ease), background var(--dur-base) var(--ease);
}

.drop-zone:hover,
.drop-zone:focus-visible,
.drop-zone.is-dragover {
  border-color: var(--accent-1);
  background: color-mix(in srgb, var(--accent-1) 5%, transparent);
}

.drop-zone__checker {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(45deg, var(--checker-a) 25%, transparent 25%, transparent 75%, var(--checker-a) 75%),
    linear-gradient(45deg, var(--checker-a) 25%, transparent 25%, transparent 75%, var(--checker-a) 75%);
  background-size: var(--checker-size) var(--checker-size);
  background-position: 0 0, calc(var(--checker-size) / 2) calc(var(--checker-size) / 2);
  opacity: 0.5;
  mask-image: radial-gradient(circle at 50% 30%, black, transparent 70%);
}

.drop-zone__content {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

.drop-zone__icon {
  color: var(--accent-1);
  margin-bottom: 14px;
}

.drop-zone__title {
  font-weight: 600;
  font-size: 1.02rem;
  margin: 0 0 6px;
}

.drop-zone__hint {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.78rem;
  color: var(--ink-soft);
  margin: 0 0 24px;
}

.upload-error {
  min-height: 20px;
  color: #E5484D;
  font-size: 0.85rem;
  text-align: center;
  margin: 10px 4px 2px;
}

/* =========================================================================
   Buttons
   ========================================================================= */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 44px;
  padding: 0 22px;
  border-radius: 999px;
  border: none;
  font-weight: 600;
  font-size: 0.92rem;
  transition: transform var(--dur-fast) var(--ease), box-shadow var(--dur-fast) var(--ease), opacity var(--dur-fast) var(--ease);
}

.btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
  transform: none !important;
}

.btn--primary {
  color: #fff;
  background: var(--accent-grad);
  box-shadow: 0 8px 20px -8px color-mix(in srgb, var(--accent-1) 60%, transparent);
}

.btn--primary:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: 0 12px 26px -8px color-mix(in srgb, var(--accent-1) 70%, transparent);
}

.btn--accent {
  color: #06251C;
  background: var(--accent-3);
  box-shadow: 0 8px 20px -8px color-mix(in srgb, var(--accent-3) 60%, transparent);
}

.btn--accent:hover:not(:disabled) {
  transform: translateY(-2px);
}

.btn--ghost {
  color: var(--ink);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
}

.btn--ghost:hover:not(:disabled) {
  border-color: var(--ink-soft);
  transform: translateY(-2px);
}

/* =========================================================================
   Editor
   ========================================================================= */

.editor {
  position: relative;
  z-index: 1;
  padding: 24px 24px 100px;
}

.editor__inner {
  max-width: 920px;
  margin: 0 auto;
}

.editor__header {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
}

.editor__heading {
  font-family: 'Sora', sans-serif;
  font-size: 1.4rem;
  font-weight: 700;
  margin: 0;
  letter-spacing: -0.01em;
}

.editor__toolbar {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.stage {
  position: relative;
  border-radius: var(--radius-lg);
  padding: 16px;
  overflow: hidden;
}

/* Processing overlay */

.processing {
  position: absolute;
  inset: 0;
  z-index: 10;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 14px;
  background: color-mix(in srgb, var(--bg) 78%, transparent);
  backdrop-filter: blur(6px);
  border-radius: var(--radius-lg);
}

.spinner {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 3px solid var(--border);
  border-top-color: var(--accent-1);
  animation: spin 800ms linear infinite;
}

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

.processing__label {
  font-size: 0.9rem;
  color: var(--ink-soft);
  font-family: 'JetBrains Mono', monospace;
}

.progress-track {
  width: 220px;
  height: 6px;
  border-radius: 999px;
  background: var(--border);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: var(--accent-grad);
  border-radius: 999px;
  transition: width var(--dur-base) var(--ease);
}

/* Compare stage */

.compare {
  position: relative;
  border-radius: var(--radius-md);
  overflow: hidden;
  aspect-ratio: 4 / 3;
  max-height: 62vh;
  background: var(--bg-elevated);
}

.compare__zoom-wrap {
  position: relative;
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.compare__img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: contain;
  transition: transform var(--dur-base) var(--ease);
  user-select: none;
  -webkit-user-drag: none;
}

.compare__result-wrap {
  position: absolute;
  inset: 0;
  clip-path: inset(0 50% 0 0);
}

.compare__checker {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(45deg, var(--checker-a) 25%, transparent 25%, transparent 75%, var(--checker-a) 75%),
    linear-gradient(45deg, var(--checker-a) 25%, transparent 25%, transparent 75%, var(--checker-a) 75%);
  background-size: var(--checker-size) var(--checker-size);
  background-position: 0 0, calc(var(--checker-size) / 2) calc(var(--checker-size) / 2);
}

.compare__handle {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 50%;
  width: 0;
  border-left: 2px dashed color-mix(in srgb, var(--ink) 60%, transparent);
  transform: translateX(-1px);
  pointer-events: none;
}

.compare__handle-grip {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  box-shadow: 0 4px 14px -4px hsl(var(--shadow-color) / 0.35);
}

.compare__handle-grip::before,
.compare__handle-grip::after {
  content: "";
  position: absolute;
  top: 50%;
  width: 0;
  height: 0;
  border-top: 5px solid transparent;
  border-bottom: 5px solid transparent;
}

.compare__handle-grip::before {
  left: 8px;
  border-right: 6px solid var(--ink-soft);
  transform: translateY(-50%);
}

.compare__handle-grip::after {
  right: 8px;
  border-left: 6px solid var(--ink-soft);
  transform: translateY(-50%);
}

.compare__range {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  margin: 0;
  opacity: 0;
  cursor: ew-resize;
  appearance: none;
  -webkit-appearance: none;
}

/* Footer controls */

.editor__footer-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  margin-top: 18px;
}

.zoom-control {
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  padding: 8px 14px;
  border-radius: 999px;
}

.zoom-control input[type="range"] {
  width: 120px;
  accent-color: var(--accent-1);
}

.zoom-value {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.78rem;
  color: var(--ink-soft);
  min-width: 40px;
}

.editor__hint {
  font-size: 0.82rem;
  color: var(--ink-soft);
  margin: 0;
}

/* =========================================================================
   Footer
   ========================================================================= */

.footer {
  position: relative;
  z-index: 1;
  border-top: 1px solid var(--border);
  padding: 32px 24px 40px;
}

.footer__inner {
  max-width: 1180px;
  margin: 0 auto;
  text-align: center;
}

.footer__brand {
  font-family: 'Sora', sans-serif;
  font-weight: 700;
  margin: 0 0 6px;
}

.footer__note {
  color: var(--ink-soft);
  font-size: 0.85rem;
  margin: 0 0 14px;
}

.footer__links {
  display: flex;
  justify-content: center;
  gap: 10px;
  font-size: 0.82rem;
  color: var(--ink-soft);
}

.footer__links a {
  color: var(--ink-soft);
  text-decoration: none;
  transition: color var(--dur-fast) var(--ease);
}

.footer__links a:hover {
  color: var(--accent-1);
}

/* =========================================================================
   Responsive
   ========================================================================= */

@media (max-width: 640px) {
  .hero { padding: 72px 16px 48px; }
  .drop-zone { padding: 40px 20px; }
  .editor__header { flex-direction: column; align-items: flex-start; }
  .editor__toolbar { width: 100%; }
  .editor__toolbar .btn { flex: 1; }
}

/* =========================================================================
   Reduced motion
   ========================================================================= */

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}