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

:root {
  /* Dark Mode Variables (Default) */
  --bg-color: #171717;
  --card-bg: #262626;
  --text-primary: #f5f5f5;
  --text-secondary: #a3a3a3;
  --border-color: #404040;
  --accent-color: #ffffff;
  --accent-text: #000000;
  --button-hover: #e5e5e5;
  --upload-bg: #262626;
  --upload-bg-hover: #333333;
  --success-bg: rgba(22, 163, 74, 0.2);
  --success-text: #4ade80;
  --error-bg: rgba(220, 38, 38, 0.2);
  --error-text: #f87171;
  --slider-track: #404040;
  --slider-thumb: #ffffff;
}

@media (prefers-color-scheme: light) {
  :root {
    /* Light Mode Variables override */
    --bg-color: #f5f5f5;
    --card-bg: #ffffff;
    --text-primary: #171717;
    --text-secondary: #525252;
    --border-color: #e5e5e5;
    --accent-color: #171717;
    --accent-text: #ffffff;
    --button-hover: #262626;
    --upload-bg: #fafafa;
    --upload-bg-hover: #f0f0f0;
    --success-bg: #dcfce7;
    --success-text: #15803d;
    --error-bg: #fee2e2;
    --error-text: #b91c1c;
    --slider-track: #e5e5e5;
    --slider-thumb: #171717;
  }
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 40px 20px;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 32px;
  width: 100%;
}

/* Header */
.header {
  text-align: center;
  margin-bottom: 24px;
}

.header h1 {
  font-size: 48px;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 16px;
  letter-spacing: -1.2px;
}

.header p {
  font-size: 18px;
  color: var(--text-secondary);
  font-weight: 400;
}

/* Card */
.card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 24px;
  padding: 32px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

/* Upload Area */
.upload-area {
  position: relative;
  border: 2px dashed var(--border-color);
  border-radius: 20px;
  padding: 48px 24px;
  text-align: center;
  transition: all 0.2s ease;
  cursor: pointer;
  background: var(--upload-bg);
}

.upload-area:hover {
  border-color: var(--text-secondary);
  background: var(--upload-bg-hover);
}

.upload-area.has-file {
  border-color: var(--success-text);
}

.upload-icon {
  width: 64px;
  height: 64px;
  margin: 0 auto 16px;
  background: var(--accent-color);
  color: var(--accent-text);
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 32px;
}

.upload-text {
  font-size: 20px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.upload-hint {
  font-size: 14px;
  color: var(--text-secondary);
}

#file-input {
  position: absolute;
  inset: 0;
  opacity: 0;
  cursor: pointer;
  z-index: 10;
}

/* Buttons */
.btn {
  width: 100%;
  padding: 18px;
  border: none;
  border-radius: 16px;
  font-size: 18px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  font-family: inherit;
  margin-top: 24px;
  letter-spacing: 0.5px;
}

.btn-primary {
  background: var(--accent-color);
  color: var(--accent-text);
}

.btn-primary:hover:not(:disabled) {
  background: var(--button-hover);
  transform: translateY(-1px);
}

.btn-primary:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
  background: var(--border-color);
  color: var(--text-secondary);
}

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

.btn-secondary.is-active {
  background: #ffffff;
  color: #0a0a0a;
  border-color: #ffffff;
}

.btn-secondary:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-secondary:hover {
  background: var(--upload-bg-hover);
  border-color: var(--text-secondary);
}

/* Preview Area */
.preview-container {
  position: relative;
  width: 100%;
  min-height: 360px;
  height: clamp(360px, 55vh, 600px);
  border-radius: 20px;
  overflow: hidden;
  background-color: var(--upload-bg);
  border: 1px solid var(--border-color);
  /* Checkerboard for transparency */
  background-image:
    linear-gradient(45deg, var(--border-color) 25%, transparent 25%),
    linear-gradient(-45deg, var(--border-color) 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, var(--border-color) 75%),
    linear-gradient(-45deg, transparent 75%, var(--border-color) 75%);
  background-size: 20px 20px;
  background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
}

.preview-wrapper {
  position: relative;
  width: 100%;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
}

.preview-image {
  max-width: 100%;
  max-height: 600px;
  object-fit: contain;
  display: block;
  user-select: none;
}

/* Ensure images stack properly for slider */
#original-image,
#processed-image {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: auto;
  height: auto;
  max-width: 100%;
  max-height: 100%;
}

.preview-placeholder {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  font-size: 16px;
  background: var(--card-bg);
  gap: 12px;
}

/* Slider */
.slider-container {
  position: relative;
  margin-top: 24px;
  padding: 0 8px;
}

.slider-container.hidden {
  display: none;
}

.slider {
  width: 100%;
  height: 4px;
  border-radius: 2px;
  background: var(--slider-track);
  outline: none;
  -webkit-appearance: none;
  appearance: none;
  cursor: pointer;
}

.slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--slider-thumb);
  cursor: pointer;
  border: 2px solid var(--card-bg);
  transition: transform 0.1s ease;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.slider::-webkit-slider-thumb:hover {
  transform: scale(1.1);
}

.slider-labels {
  display: flex;
  justify-content: space-between;
  margin-top: 12px;
  font-size: 14px;
  color: var(--text-secondary);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 1px;
}

/* Status Messages */
.status {
  text-align: center;
  padding: 16px;
  border-radius: 16px;
  font-size: 15px;
  font-weight: 500;
  transition: all 0.3s ease;
  border: 1px solid transparent;
}

.status.info {
  background: var(--upload-bg);
  color: var(--text-secondary);
  border-color: var(--border-color);
}

.status.success {
  background: var(--success-bg);
  color: var(--success-text);
  border-color: var(--success-bg);
}

.status.error {
  background: var(--error-bg);
  color: var(--error-text);
  border-color: var(--error-bg);
}

.status.busy {
  background: var(--upload-bg);
  color: var(--text-primary);
  border-color: var(--text-secondary);
}

/* Footer */
.footer {
  margin-top: auto;
  text-align: center;
  padding: 24px;
  color: var(--text-secondary);
  border-top: 1px solid var(--border-color);
}

.footer-content {
  display: flex;
  flex-direction: column;
  gap: 8px;
  align-items: center;
}

.footer a {
  color: var(--text-primary);
  text-decoration: none;
  transition: color 0.2s ease;
  font-weight: 500;
  border-bottom: 1px dotted var(--text-secondary);
}

.footer a:hover {
  color: var(--text-secondary);
  border-bottom-style: solid;
}

.footer-links {
  display: flex;
  gap: 20px;
  margin-top: 8px;
}

@media (max-width: 640px) {
  .header h1 {
    font-size: 36px;
  }
}