:root {
  --bg: #f7f7f5;
  --surface: #ffffff;
  --ink: #1a1a1a;
  --muted: #5b5b5b;
  --border: #e3e3e0;
  --accent: #1f4f8b;
  --accent-ink: #ffffff;
  --accent-tint: rgba(31, 79, 139, 0.06);
  --code-bg: #fafafa;
  --error-bg: #fde2e2;
  --error-ink: #842029;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.5;
}

.topbar {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 1rem 1.5rem;
  display: flex;
  align-items: baseline;
  gap: 1rem;
}

.brand {
  font-weight: 800;
  font-size: 1.35rem;
  letter-spacing: 0.01em;
  color: var(--accent);
}

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

.container {
  max-width: 720px;
  margin: 2.5rem auto;
  padding: 0 1.5rem;
}

.upload-card,
.result-card,
.interstitial-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 2rem;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
}

.result-card,
.interstitial,
.error-card {
  margin-top: 1.5rem;
}

h1 {
  margin: 0 0 0.5rem;
  font-size: 1.6rem;
}

h2 {
  margin: 0;
  font-size: 1.15rem;
}

.lead {
  color: var(--muted);
  margin: 0 0 1.5rem;
}

.upload-form {
  display: flex;
  flex-direction: column;
  gap: 1.1rem;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.field-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.field-label {
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}

.field-input {
  width: 100%;
  font-family: inherit;
  font-size: 0.95rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.55rem 0.75rem;
  background: var(--surface);
  color: var(--ink);
}

.field-input:focus {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

.file-label {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  border: 1.5px dashed var(--border);
  padding: 1.5rem;
  border-radius: 8px;
  cursor: pointer;
  background: #fafafa;
}

.file-label:hover {
  border-color: var(--accent);
}

.file-label-title {
  font-weight: 600;
}

.file-label-hint {
  color: var(--muted);
  font-size: 0.9rem;
}

.file-label input[type="file"] {
  margin-top: 0.5rem;
}

button.primary,
a.primary {
  background: var(--accent);
  color: var(--accent-ink);
  border: none;
  border-radius: 6px;
  padding: 0.65rem 1.1rem;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  display: inline-block;
}

button.primary:hover,
a.primary:hover {
  filter: brightness(0.92);
}

button.primary:disabled {
  opacity: 0.55;
  cursor: progress;
}

button.secondary,
a.secondary {
  background: var(--surface);
  color: var(--accent);
  border: 1px solid var(--accent);
  border-radius: 6px;
  padding: 0.4rem 0.85rem;
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  display: inline-block;
}

button.secondary:hover,
a.secondary:hover {
  background: var(--accent-tint);
}

.result-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

.result-header h2 {
  margin-right: auto;
}

.result-actions {
  display: flex;
  gap: 0.5rem;
}

pre.result {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1rem;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: 0.88rem;
  line-height: 1.55;
  color: var(--ink);
  overflow: auto;
  max-height: 60vh;
  margin: 0;
  white-space: pre-wrap;
  word-break: break-word;
}

.interstitial-card {
  text-align: center;
}

.interstitial-card h2 {
  margin: 1.1rem 0 0.4rem;
  font-size: 1.25rem;
}

.interstitial-filename {
  color: var(--muted);
  margin: 0 0 0.5rem;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: 0.9rem;
  word-break: break-all;
}

.interstitial-elapsed {
  color: var(--muted);
  font-size: 0.9rem;
  margin: 0;
}

.spinner {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 4px solid var(--border);
  border-top-color: var(--accent);
  margin: 0 auto;
  animation: spin 0.9s linear infinite;
}

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

@media (prefers-reduced-motion: reduce) {
  .spinner {
    animation: none;
    border-top-color: var(--border);
    background: var(--accent);
  }
}

.error-card {
  background: var(--surface);
  border: 1px solid var(--error-ink);
  border-left-width: 4px;
  border-radius: 10px;
  padding: 1.75rem;
}

.error-card h2 {
  margin: 0 0 0.75rem;
  color: var(--error-ink);
}

.error-detail {
  background: var(--error-bg);
  color: var(--error-ink);
  border-radius: 6px;
  padding: 0.75rem 1rem;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: 0.9rem;
  white-space: pre-wrap;
  word-break: break-word;
  margin: 0 0 1rem;
}

.app-footer {
  max-width: 720px;
  margin: 0 auto 2.5rem;
  padding: 0 1.5rem;
  text-align: center;
  color: var(--muted);
  font-size: 0.85rem;
}