:root {
  --bg-1: #6366f1;
  --bg-2: #8b5cf6;
  --card-bg: #ffffff;
  --text: #1e1b2e;
  --text-muted: #6b7280;
  --accent: #6366f1;
  --accent-hover: #4f46e5;
  --border: #e5e7eb;
  --success-bg: #ecfdf5;
  --success-text: #047857;
  --success-border: #a7f3d0;
  --error-bg: #fef2f2;
  --error-text: #b91c1c;
  --error-border: #fecaca;
}

* {
  box-sizing: border-box;
}

/* .status/.result/.error below set display:flex, which would otherwise
   override the browser's default "hidden means display:none" rule. */
[hidden] {
  display: none !important;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 32px 16px;
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: linear-gradient(135deg, var(--bg-1), var(--bg-2));
  color: var(--text);
}

.card {
  width: 100%;
  max-width: 480px;
  background: var(--card-bg);
  border-radius: 20px;
  padding: 40px 36px;
  box-shadow: 0 20px 60px rgba(30, 27, 46, 0.25);
}

h1 {
  margin: 0 0 8px;
  font-size: 1.6rem;
  font-weight: 700;
  text-align: center;
}

.subtitle {
  margin: 0 0 28px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.4;
}

.tabs {
  display: flex;
  background: #f3f4f6;
  border-radius: 12px;
  padding: 4px;
  margin-bottom: 20px;
  gap: 4px;
}

.tab {
  flex: 1;
  border: none;
  background: transparent;
  padding: 10px 0;
  border-radius: 9px;
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-muted);
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease;
}

.tab.active {
  background: var(--card-bg);
  color: var(--accent);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

#dropzone {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border: 2px dashed var(--border);
  border-radius: 14px;
  padding: 32px 16px;
  cursor: pointer;
  text-align: center;
  transition: border-color 0.15s ease, background 0.15s ease;
}

#dropzone:hover,
#dropzone.dragover {
  border-color: var(--accent);
  background: #f5f5ff;
}

.dz-icon {
  font-size: 2rem;
}

.dz-text {
  color: var(--text-muted);
  font-size: 0.9rem;
}

.dz-filename {
  font-weight: 600;
  font-size: 0.9rem;
  word-break: break-all;
}

#submit-btn {
  width: 100%;
  margin-top: 18px;
  padding: 13px;
  border: none;
  border-radius: 12px;
  background: var(--accent);
  color: white;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s ease, transform 0.1s ease;
}

#submit-btn:hover:not(:disabled) {
  background: var(--accent-hover);
}

#submit-btn:active:not(:disabled) {
  transform: scale(0.98);
}

#submit-btn:disabled {
  background: #c7c9d9;
  cursor: not-allowed;
}

.status,
.result,
.error {
  margin-top: 18px;
  padding: 14px 16px;
  border-radius: 12px;
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  gap: 10px;
}

.status {
  background: #f3f4f6;
  color: var(--text-muted);
}

.spinner {
  width: 16px;
  height: 16px;
  border: 2px solid #d1d5db;
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
  flex-shrink: 0;
}

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

.result {
  background: var(--success-bg);
  color: var(--success-text);
  border: 1px solid var(--success-border);
  flex-direction: column;
  align-items: stretch;
}

.result p {
  margin: 0 0 10px;
  font-weight: 600;
}

.download-btn {
  display: inline-block;
  text-align: center;
  background: var(--success-text);
  color: white;
  text-decoration: none;
  padding: 10px;
  border-radius: 10px;
  font-weight: 600;
  transition: opacity 0.15s ease;
}

.download-btn:hover {
  opacity: 0.9;
}

.error {
  background: var(--error-bg);
  color: var(--error-text);
  border: 1px solid var(--error-border);
  font-weight: 500;
}

@media (prefers-color-scheme: dark) {
  :root {
    --card-bg: #1f2130;
    --text: #f3f4f6;
    --text-muted: #9ca3af;
    --border: #383b52;
  }

  .tabs {
    background: #14151f;
  }

  .tab.active {
    background: var(--card-bg);
  }

  #dropzone:hover,
  #dropzone.dragover {
    background: #262842;
  }

  .status {
    background: #14151f;
  }

  #submit-btn:disabled {
    background: #3a3c52;
    color: #8a8ca3;
  }
}