* {
  box-sizing: border-box;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
  background: #f5f5f7;
  margin: 0;
  padding: 24px;
  color: #333;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  background: #fff;
  border-radius: 16px;
  padding: 24px 24px 32px;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.03);
}

h1 {
  font-size: 24px;
  margin-bottom: 4px;
}

.subtitle {
  font-size: 14px;
  color: #666;
  margin-bottom: 16px;
}

.badge {
  display: inline-block;
  font-size: 11px;
  background: #e8f5e9;
  color: #2e7d32;
  padding: 2px 8px;
  border-radius: 999px;
  margin-left: 8px;
  vertical-align: middle;
}

.drop-area {
  border: 2px dashed #bbb;
  border-radius: 12px;
  padding: 32px 20px;
  text-align: center;
  cursor: pointer;
  background: #fafafa;
  transition: all 0.2s ease;
  margin-bottom: 20px;
}

.drop-area.is-dragover {
  border-color: #1976d2;
  background: #e3f2fd;
}

.drop-area p {
  margin: 8px 0;
  font-size: 14px;
}

.drop-area .strong {
  font-weight: 600;
}

.drop-area label {
  color: #1976d2;
  font-weight: 600;
  cursor: pointer;
  text-decoration: underline;
}

.options {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 16px;
  padding: 12px 16px;
  border-radius: 12px;
  background: #fafafa;
}

.option-group {
  min-width: 200px;
  font-size: 13px;
}

.option-group label {
  display: block;
  font-size: 12px;
  margin-bottom: 4px;
  color: #555;
}

.option-inline {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  margin-bottom: 8px;
}

input[type="number"],
input[type="range"] {
  width: 100%;
}

input[type="number"] {
  padding: 6px 8px;
  border-radius: 6px;
  border: 1px solid #ccc;
  font-size: 13px;
}

.convert-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 18px;
  border-radius: 999px;
  border: none;
  background: #1976d2;
  color: #fff;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  margin-top: 4px;
  margin-bottom: 12px;
  box-shadow: 0 2px 5px rgba(182, 208, 235, 0.3);
  transition: transform 0.1s ease, box-shadow 0.1s ease,
    background 0.1s ease;
}

.convert-btn:disabled {
  opacity: 0.6;
  cursor: default;
  box-shadow: none;
}

.convert-btn:not(:disabled):hover {
  background: #1565c0;
  transform: translateY(-1px);
  box-shadow: 0 6px 14px rgba(25, 118, 210, 0.4);
}

.convert-btn span.icon {
  font-size: 16px;
}

.status {
  font-size: 13px;
  color: #555;
  min-height: 18px;
  margin-bottom: 12px;
}

.file-list {
  list-style: none;
  padding: 0;
  margin: 0;
  border-top: 1px solid #eee;
}

.file-list li {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 4px;
  font-size: 13px;
  border-bottom: 1px solid #f0f0f0;
}

.file-name {
  flex: 1;
  margin-right: 8px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.file-size {
  font-size: 12px;
  color: #777;
  margin-right: 8px;
  white-space: nowrap;
}

.download-link {
  font-size: 12px;
  color: #1976d2;
  text-decoration: underline;
  cursor: pointer;
  white-space: nowrap;
}

.download-all {
  margin-top: 10px;
  font-size: 12px;
}

.download-all button {
  border: none;
  border-radius: 999px;
  background: #388e3c;
  color: #fff;
  font-size: 12px;
  padding: 6px 14px;
  cursor: pointer;
  font-weight: 600;
}

.download-all button:hover {
  background: #2e7d32;
}

.hint {
  font-size: 11px;
  color: #999;
  margin-top: 4px;
}

.howto {
  margin-top: 16px;
  font-size: 13px;
  background: #fafafa;
  border-radius: 12px;
  padding: 12px 16px;
}

.howto summary {
  font-weight: 600;
  cursor: pointer;
  list-style: none;
}

.howto summary::-webkit-details-marker {
  display: none;
}

.howto summary::before {
  content: "▶ ";
  font-size: 11px;
  color: #1976d2;
}

.howto[open] summary::before {
  content: "▼ ";
}

.howto ol {
  padding-left: 1.2em;
  margin: 8px 0 0;
}

.howto li {
  margin-bottom: 4px;
}

.tooltip-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-left: 4px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  border: 1px solid #999;
  font-size: 11px;
  color: #555;
  cursor: help;
}

.about-section {
  margin-top: 24px;
  font-size: 13px;
  line-height: 1.7;
  background: #f9fafb;
  border-radius: 12px;
  padding: 16px 18px;
  border: 1px solid #eee;
}

.about-section h2 {
  font-size: 16px;
  margin: 0 0 8px;
}

.about-section ul {
  margin: 8px 0 0;
  padding-left: 1.2em;
}

.about-section li {
  margin-bottom: 4px;
}

.about-section .hint {
  font-size: 11px;
  color: #999;
  margin-top: 8px;
}

@media (max-width: 600px) {
  .options {
    flex-direction: column;
  }
}