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

:root {
  --bg: #0f1117;
  --surface: #1a1d27;
  --surface2: #22263a;
  --accent: #6c63ff;
  --accent-hover: #857dff;
  --text: #e8eaf6;
  --text-muted: #8a8fad;
  --success: #4caf82;
  --error: #e05c5c;
  --border: #2e3250;
  --radius: 16px;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.45);
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Segoe UI', system-ui, sans-serif;
  min-height: 100vh;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 2rem 1rem;
}

.page {
  width: 100%;
  max-width: 700px;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

/* Header */
header {
  text-align: center;
}

header h1 {
  font-size: 2.2rem;
  font-weight: 700;
  letter-spacing: -0.5px;
}

header .subtitle {
  color: var(--text-muted);
  margin-top: 0.4rem;
  font-size: 1rem;
}

/* Card */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  box-shadow: var(--shadow);
}

/* Drop Zone */
#dropZone {
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  border: 2px dashed var(--border);
}

#dropZone:hover,
#dropZone.drag-over {
  border-color: var(--accent);
  background: var(--surface2);
}

.drop-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
  text-align: center;
}

.drop-icon {
  font-size: 3rem;
}

.drop-text {
  font-size: 1.1rem;
  font-weight: 600;
}

.drop-hint {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Preview */
.preview-row {
  display: flex;
  gap: 1.5rem;
  align-items: center;
}

#previewImg {
  max-width: 140px;
  max-height: 140px;
  border-radius: 10px;
  object-fit: contain;
  background: var(--surface2);
  border: 1px solid var(--border);
  padding: 0.25rem;
}

.file-info {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  font-size: 0.95rem;
  color: var(--text-muted);
}

.file-info strong {
  color: var(--text);
}

/* Format Grid */
#convertSection h2 {
  font-size: 1.1rem;
  margin-bottom: 1rem;
  color: var(--text-muted);
  font-weight: 500;
}

.format-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-bottom: 1.5rem;
}

.fmt-btn {
  background: var(--surface2);
  border: 2px solid var(--border);
  color: var(--text-muted);
  border-radius: 10px;
  padding: 0.55rem 1.2rem;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s;
  letter-spacing: 0.5px;
}

.fmt-btn:hover {
  border-color: var(--accent);
  color: var(--text);
}

.fmt-btn.active {
  border-color: var(--accent);
  background: rgba(108, 99, 255, 0.18);
  color: var(--accent-hover);
}

.btn-convert {
  width: 100%;
  padding: 0.9rem;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 12px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.2s;
  letter-spacing: 0.3px;
}

.btn-convert:hover {
  background: var(--accent-hover);
}

/* Progress */
.progress-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  padding: 1rem 0;
}

.spinner {
  width: 48px;
  height: 48px;
  border: 4px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* Result */
.result-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  text-align: center;
}

.result-icon {
  font-size: 2.5rem;
}

.result-text {
  font-size: 1.1rem;
  font-weight: 600;
}

.btn-download {
  display: inline-block;
  padding: 0.8rem 2rem;
  background: var(--success);
  color: #fff;
  border-radius: 12px;
  text-decoration: none;
  font-weight: 700;
  font-size: 1rem;
  transition: opacity 0.2s;
}

.btn-download:hover {
  opacity: 0.85;
}

.btn-reset {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-muted);
  border-radius: 10px;
  padding: 0.55rem 1.4rem;
  cursor: pointer;
  font-size: 0.9rem;
  transition: border-color 0.15s, color 0.15s;
}

.btn-reset:hover {
  border-color: var(--accent);
  color: var(--text);
}

/* Error card */
.error-card {
  border-color: var(--error);
}

/* Footer */
footer {
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
  padding-bottom: 1rem;
}

@media (max-width: 480px) {
  .preview-row {
    flex-direction: column;
    align-items: flex-start;
  }
}