:root {
  /* Premium Fintech Palette */
  --bg-app: #0b0c10;
  --bg-surface: #16181d;
  --bg-surface-hover: #1c1f26;
  --bg-input: #0f1115;
  
  --primary: #00FF85;
  --primary-dim: rgba(0, 255, 133, 0.12);
  --primary-glow: rgba(0, 255, 133, 0.25);
  
  --border: #24272e;
  --border-hover: #353945;
  
  --text-main: #f5f5f7;
  --text-muted: #808191;
  --text-dim: #4a4d5a;
  
  --success: #00FF85;
  --error: #ff4d4d;
  
  --radius-lg: 16px;
  --radius-md: 12px;
  --radius-sm: 8px;
  
  --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --shadow-premium: 0 10px 30px rgba(0, 0, 0, 0.3);
}

[data-theme="light"] {
  --bg-app: #f4f7fa;
  --bg-surface: #ffffff;
  --bg-surface-hover: #f9fbff;
  --bg-input: #f0f2f5;
  --border: #e2e8f0;
  --border-hover: #cbd5e1;
  --text-main: #1a1d23;
  --text-muted: #64748b;
  --text-dim: #94a3b8;
  --shadow-premium: 0 10px 30px rgba(0, 0, 0, 0.04);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: 'Inter', sans-serif;
  background-color: var(--bg-app);
  color: var(--text-main);
  min-height: 100vh;
  line-height: 1.6;
}

#app {
  max-width: 960px;
  margin: 0 auto;
  padding: 4rem 2rem;
}

/* Header */
header {
  margin-bottom: 5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo h1 {
  font-size: 1.8rem;
  font-weight: 800;
  letter-spacing: -0.04em;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.logo h1 img {
  height: 44px;
  filter: drop-shadow(0 0 12px var(--primary-glow));
}

.logo p {
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 500;
  margin-top: 0.25rem;
  margin-left: 0.25rem;
}

#theme-toggle {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  color: var(--text-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
  box-shadow: var(--shadow-premium);
}

#theme-toggle:hover {
  border-color: var(--primary);
  color: var(--primary);
  transform: translateY(-2px);
}

/* Upload Hero */
#upload-section {
  margin-bottom: 4rem;
}

#drop-zone {
  background: var(--bg-surface);
  border: 2px dashed var(--border);
  border-radius: var(--radius-lg);
  padding: 6rem 2rem;
  text-align: center;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: var(--shadow-premium);
  position: relative;
  overflow: hidden;
}

#drop-zone::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 50% 0%, var(--primary-dim) 0%, transparent 70%);
  opacity: 0;
  transition: var(--transition);
}

#drop-zone:hover {
  border-color: var(--primary);
  background: var(--bg-surface-hover);
  transform: translateY(-4px);
}

#drop-zone:hover::before {
  opacity: 1;
}

#drop-zone i {
  color: var(--primary);
  font-size: 3rem;
  margin-bottom: 2rem;
  filter: drop-shadow(0 0 20px var(--primary-glow));
  position: relative;
}

#drop-zone p {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  position: relative;
}

#drop-zone span {
  color: var(--text-muted);
  display: block;
  margin-top: 0.5rem;
  position: relative;
}

/* Options Panel */
#upload-options {
  margin-top: 2rem;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 2rem;
  box-shadow: var(--shadow-premium);
}

.option-group {
  display: flex;
  align-items: center;
  gap: 1rem;
}

label {
  color: var(--text-muted);
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

select, input {
  background: var(--bg-input);
  border: 1px solid var(--border);
  color: var(--text-main);
  padding: 0.6rem 1rem;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 500;
  outline: none;
  transition: var(--transition);
}

select:focus, input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-dim);
}

.input-group {
  display: flex;
  align-items: center;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding-left: 0.75rem;
}

.prefix {
  color: var(--text-dim);
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem;
}

#custom-alias {
  border: none;
  background: transparent;
  width: 160px;
}

/* Files Section */
.section-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 2rem;
  padding: 0 0.5rem;
}

.section-header h2 {
  font-size: 1.5rem;
  font-weight: 800;
  letter-spacing: -0.02em;
}

#files-list {
  display: grid;
  gap: 1.25rem;
}

.file-item {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: var(--transition);
  box-shadow: var(--shadow-premium);
}

.file-item:hover {
  border-color: var(--primary);
  transform: scale(1.01);
  background: var(--bg-surface-hover);
}

.file-main {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.file-icon-wrapper {
  width: 52px;
  height: 52px;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: var(--primary);
  transition: var(--transition);
}

.file-item:hover .file-icon-wrapper {
  border-color: var(--primary);
  box-shadow: 0 0 15px var(--primary-dim);
}

.file-info h4 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 0.4rem;
}

.file-meta {
  display: flex;
  gap: 1.5rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
}

.file-meta i {
  margin-right: 0.4rem;
  color: var(--text-dim);
}

/* Actions */
.file-actions {
  display: flex;
  gap: 0.75rem;
}

.btn-action {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--bg-input);
  color: var(--text-muted);
  cursor: pointer;
  transition: var(--transition);
}

.btn-action:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: var(--bg-surface);
}

.btn-delete:hover {
  border-color: var(--error);
  color: var(--error);
  background: rgba(255, 77, 77, 0.1);
}

/* Empty State */
.empty-state {
  padding: 5rem 2rem;
  text-align: center;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  color: var(--text-muted);
}

.empty-state i {
  font-size: 3rem;
  margin-bottom: 1.5rem;
  opacity: 0.3;
}

.empty-state p {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
}

/* Progress & Toasts */
.progress-fill {
  background: linear-gradient(90deg, var(--primary), #00ffcc);
}

.toast {
  background: #1c1f26;
  border: 1px solid var(--border);
  backdrop-filter: blur(12px);
  border-radius: var(--radius-md);
  padding: 1.25rem 1.5rem;
  color: white;
  box-shadow: 0 20px 40px rgba(0,0,0,0.4);
}

@media (max-width: 640px) {
  #app { padding: 2rem 1rem; }
  .file-item { flex-direction: column; align-items: flex-start; gap: 1.5rem; }
  .file-actions { width: 100%; justify-content: flex-end; }
  #upload-options { flex-direction: column; align-items: stretch; }
}

/* PIN Overlay */
#pin-overlay {
  position: fixed;
  inset: 0;
  background: var(--bg-app);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
}

#pin-overlay.hidden {
  display: none;
}

.pin-container {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 3rem;
  max-width: 400px;
  width: 90%;
  text-align: center;
  box-shadow: var(--shadow-premium);
}

.pin-container .logo-img {
  height: 36px;
  margin-bottom: 1rem;
  filter: drop-shadow(0 0 12px var(--primary-glow));
}

.pin-container h2 {
  font-size: 1.5rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
  color: var(--text-main);
}

.pin-container p {
  color: var(--text-muted);
  margin-bottom: 2rem;
  font-size: 0.95rem;
}

.pin-input-group {
  display: flex;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

#pin-input {
  flex: 1;
  padding: 1rem;
  font-size: 1.1rem;
  text-align: center;
  letter-spacing: 0.3em;
  background: var(--bg-input);
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  color: var(--text-main);
  outline: none;
  transition: var(--transition);
}

#pin-input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 4px var(--primary-dim);
}

#pin-input.error {
  border-color: var(--error);
  animation: shake 0.4s ease;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20%, 60% { transform: translateX(-8px); }
  40%, 80% { transform: translateX(8px); }
}

#pin-submit {
  padding: 1rem 1.5rem;
  background: var(--primary);
  border: none;
  border-radius: var(--radius-md);
  color: var(--bg-app);
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
}

#pin-submit:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px var(--primary-glow);
}

#pin-error {
  color: var(--error);
  font-size: 0.9rem;
  margin-top: 0.5rem;
  min-height: 1.4em;
}