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

body {
  font-family: 'SF Pro Display', -apple-system, BlinkMacSystemFont, 'Segoe UI',
    Roboto, sans-serif;
  line-height: 1.6;
  color: #1f2937;
  background: #ffffff;
  min-height: 100vh;
  padding: 2rem;
}

.container {
  max-width: 600px;
  margin: 0 auto;
}

h1 {
  font-size: 2.5rem;
  font-weight: 600;
  margin-bottom: 1rem;
  text-align: center;
  color: #1f2937;
  letter-spacing: -0.02em;
}

.description {
  text-align: center;
  color: #6b7280;
  font-size: 0.875rem;
  line-height: 1.5;
  margin-bottom: 3rem;
  margin-left: auto;
  margin-right: auto;
}

.description a {
  color: #374151;
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
}

.description a:hover {
  color: #1f2937;
}

.main-area {
  position: relative;
  min-height: 400px;
  margin-bottom: 2rem;
}

.upload {
  border: 1px solid #e5e7eb;
  padding: 4rem 2rem;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.2s ease;
  min-height: 400px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1rem;
}

.upload:hover {
  border-color: #cbd5e1;
}

.upload.dragover {
  border-color: #9ca3af;
}

.upload p {
  color: #6b7280;
  font-weight: 400;
}

.upload p:nth-of-type(2) {
  font-size: 0.75rem;
}

.image-display {
  position: relative;
  text-align: center;
}

.image-display img {
  width: 100%;
  height: auto;
  max-height: 500px;
  object-fit: contain;
  transition: opacity 0.2s ease;
}

.processing-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.processing-content {
  text-align: center;
}

.spinner {
  width: 48px;
  height: 48px;
  border: 4px solid #e5e7eb;
  border-top: 4px solid #6b7280;
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

.controls {
  margin-bottom: 2rem;
  text-align: center;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 2rem;
  flex-wrap: wrap;
  padding: 1rem;
}

.controls label {
  display: inline-flex;
  align-items: center;
  font-size: 0.875rem;
  font-weight: 500;
  color: #374151;
  gap: 1rem;
}

#hdrSlider {
  width: 200px;
  height: 4px;
  background: #e5e7eb;
  outline: none;
  -webkit-appearance: none;
  cursor: pointer;
  transition: all 0.2s ease;
}

#hdrSlider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: #6b7280;
  cursor: pointer;
  transition: all 0.2s ease;
}

#hdrSlider::-webkit-slider-thumb:hover {
  background: #374151;
}

#hdrSlider::-moz-range-thumb {
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: #6b7280;
  cursor: pointer;
  border: none;
}

#hdrValue {
  font-weight: 600;
  color: #374151;
  font-size: 0.875rem;
  min-width: 2rem;
  text-align: center;
}

/* Shared button styles */
.btn {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
  line-height: 1.5;
  border: 1px solid;
  text-decoration: none;
  display: inline-block;
  font-family: inherit;
}

.reset-btn {
  background: transparent;
  border-color: #d1d5db;
  color: #6b7280;
}

.reset-btn:hover {
  color: #374151;
  border-color: #9ca3af;
}

.download-btn {
  background: #374151;
  border-color: #374151;
  color: white;
}

.download-btn[href]:hover {
  background: #1f2937;
  border-color: #1f2937;
}

.download-btn:not([href]) {
  background: #e5e7eb;
  border-color: #e5e7eb;
  color: #9ca3af;
  cursor: not-allowed;
  pointer-events: none;
}

.error {
  text-align: center;
  padding: 1rem;
  color: #dc2626;
  font-size: 0.875rem;
  font-weight: 500;
}

.info {
  text-align: center;
  margin-top: 1rem;
  margin-bottom: 2rem;
}

.info p {
  color: #6b7280;
  font-size: 0.75rem;
  line-height: 1.5;
  max-width: 400px;
  margin: 0 auto;
}

.github-link {
  text-align: center;
  margin-top: 5rem;
}

.github-link a {
  color: #6b7280;
  font-size: 0.75rem;
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
}

.github-link a:hover {
  color: #374151;
}

/* Examples section */
.examples {
  margin: 3rem 0;
  text-align: center;
  background: rgba(255, 255, 255, 0.7);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 16px;
  padding: 2rem;
}

.examples h2 {
  font-size: 1.5rem;
  font-weight: 600;
  color: #374151;
  margin-bottom: 1.5rem;
  letter-spacing: -0.025em;
}

.example-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  margin-bottom: 1rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.example-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  background: rgba(255, 255, 255, 0.5);
  border-radius: 12px;
  padding: 1rem;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.example-item img {
  width: 100%;
  height: auto;
  max-width: 200px;
  border-radius: 8px;
  transition: all 0.3s ease;
}

.example-label {
  margin-top: 0.75rem;
  font-size: 0.875rem;
  font-weight: 500;
  color: #6b7280;
  letter-spacing: 0.025em;
}

.example-note {
  color: #9ca3af;
  font-size: 0.75rem;
  font-style: italic;
  margin-top: 0.5rem;
  max-width: 400px;
  margin-left: auto;
  margin-right: auto;
}

@media (max-width: 640px) {
  body {
    padding: 1rem;
  }

  h1 {
    font-size: 2rem;
    margin-bottom: 2rem;
  }

  .controls {
    flex-direction: column;
    gap: 1rem;
    padding: 0.5rem;
  }

  .upload {
    padding: 3rem 1.5rem;
  }

  #hdrSlider {
    width: 160px;
  }

  .spinner {
    width: 28px;
    height: 28px;
    border-width: 2px;
  }

  .examples {
    margin: 2rem 0;
    padding: 1.5rem;
  }

  .example-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }

  .example-item img {
    max-width: 150px;
  }

  .examples h2 {
    font-size: 1.25rem;
  }
}

/* Focus styles for accessibility */
button:focus,
input[type='range']:focus,
a.btn:focus {
  outline: 2px solid #6b7280;
  outline-offset: 2px;
}