html { box-sizing: border-box; }
*, *::before, *::after { box-sizing: inherit; }

:root {
  --gradient-bg: #1e1e1e;
  --gradient-header: linear-gradient(135deg, #2a2a2a, #1e1e1e);
  --gradient-btn: linear-gradient(135deg, #3a3f51, #2c2f3a);
  --gradient-btn-hover: linear-gradient(135deg, #4b5168, #343845);
  --hover-glow: 0 0 25px rgba(0, 200, 255, 0.6);
  --text: #f5f5f5;
  --success: #28a745;
  --success-hover: #218838;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  margin: 0;
  padding: 20px;
  background: var(--gradient-bg);
  scroll-behavior: smooth;
  color: var(--text);
  overflow: auto;
}

canvas#background-stars {
  position: fixed;
  top: 0;
  left: 0;
  z-index: -2;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.container {
  text-align: center;
  background: linear-gradient(
    145deg,
    rgba(20, 20, 20, 0.7) 0%,
    rgba(30, 30, 30, 0.6) 40%,
    rgba(40, 40, 40, 0.5) 70%,
    rgba(60, 60, 60, 0.4) 100%
  );
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 15px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  max-width: 550px;
  width: 100%;
  padding: 30px;
}

h1 {
  font-size: 2em;
  margin-bottom: 20px;
  color: var(--text);
  text-shadow: 0 0 10px rgba(0, 200, 255, 0.6);
}

.arrange-heading {
  font-size: 1.1em;
  margin: 10px 0 5px;
  font-weight: 500;
}

.help-text {
  font-size: 0.85rem;
  opacity: 0.8;
  margin-top: -10px;
}

.file-label {
  display: inline-block;
  margin: 20px 0 8px;
  padding: 14px 20px;
  border: 2px dashed var(--text);
  border-radius: 12px;
  background: #444;
  cursor: pointer;
  transition: border-color 0.3s, transform 0.3s, box-shadow 0.3s;
  text-align: center;
  width: 100%;
  box-sizing: border-box;
  color: var(--text);
  user-select: none;
}

.file-label:hover {
  border-color: #00c8ff;
  transform: scale(1.04);
  box-shadow: var(--hover-glow);
}

.drop-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 200, 255, 0.1);
  border: 3px dashed rgba(0, 200, 255, 0.7);
  z-index: 10;
  display: grid;
  place-items: center;
  font-size: 1.3rem;
  color: #dff7ff;
  backdrop-filter: blur(2px);
}

button {
  padding: 12px 20px;
  font-size: 1rem;
  background: var(--gradient-btn);
  color: white;
  border: none;
  border-radius: 12px;
  cursor: pointer;
  transition: background 0.3s, transform 0.3s;
  margin: 12px 6px 0;
}

button:hover {
  background: var(--gradient-btn-hover);
  transform: translateY(-1px);
}

button#resetButton {
  background: linear-gradient(135deg, #ff4e50, #c0392b);
  box-shadow: 0 5px 15px rgba(255, 78, 80, 0.3);
}

button#resetButton:hover {
  background: linear-gradient(135deg, #c0392b, #ff4e50);
}

button.download-ready {
  background: linear-gradient(135deg, var(--success), var(--success-hover));
}

.radio-group,
.quality-group,
.batch-group,
.password-group {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin: 10px 0;
  font-size: 0.95em;
  align-items: center;
  flex-wrap: wrap;
}

.password-group input[type="password"] {
  min-width: 180px;
  padding: 8px 10px;
  border-radius: 8px;
  border: 1px solid rgba(255,255,255,0.15);
  background: rgba(0,0,0,0.25);
  color: var(--text);
}

#batchSelect {
  padding: 6px 8px;
  border-radius: 8px;
  border: 1px solid rgba(255,255,255,0.15);
  background: rgba(0,0,0,0.25);
  color: var(--text);
}

#qualitySlider {
  width: 180px;
  accent-color: #00c8ff;
  cursor: pointer;
}

#qualityValue {
  font-weight: bold;
  margin-left: 5px;
}

.preview-container {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  margin: 12px 0;
}

.preview-item {
  position: relative;
  width: 96px;
  height: 96px;
  border: 2px solid #00c8ff;
  border-radius: 10px;
  overflow: hidden;
  background: #222;
  transition: transform 0.2s ease;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: grab;
  opacity: 0;
  animation: fadeIn 0.3s ease forwards;
}

@keyframes fadeIn { to { opacity: 1; } }

.preview-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  pointer-events: none;
}

.preview-item .delete-btn {
  position: absolute;
  top: 1px;
  right: 6px;
  transform: translate(50%, -50%);
  width: 24px;
  height: 24px;
  padding: 0;
  line-height: 1;
  border: none;
  border-radius: 9999px;
  background: rgba(255, 77, 77, 0.98);
  color: #fff;
  font-size: 14px;
  display: grid;
  place-items: center;
  box-sizing: content-box;
  z-index: 2;
  cursor: pointer;
  transition: transform 0.15s ease, background 0.2s ease;
}

.preview-item .delete-btn:hover {
  background: #e60000;
  transform: translate(50%, -50%) scale(1.05);
}

.preview-item .spinner {
  width: 28px;
  height: 28px;
  border: 3px solid rgba(255,255,255,0.25);
  border-top-color: #00c8ff;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

.status-badge {
  position: absolute;
  left: 6px;
  bottom: 6px;
  font-size: 10px;
  padding: 3px 6px;
  border-radius: 6px;
  background: rgba(0,0,0,0.5);
  border: 1px solid rgba(255,255,255,0.2);
}

.fade-out {
  opacity: 0;
  transform: scale(0.9);
  transition: opacity 0.3s ease, transform 0.3s ease;
}

.processing-dots { display: block; }
.processing-dots::after {
  content: '...';
  display: inline-block;
  animation: dots 1s steps(3, end) infinite;
}
@keyframes dots {
  0% { content: ''; }
  33% { content: '.'; }
  66% { content: '..'; }
  100% { content: '...'; }
}

.hidden { display: none !important; }

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

@media (max-width: 520px) {
  .container { max-width: 94vw; padding: 22px; }
  .preview-item { width: min(28vw, 110px); height: min(28vw, 110px); }
  button { width: 100%; }
}