:root {
  --bg: #0d1117;
  --surface: #161b22;
  --border: #30363d;
  --text: #e6edf3;
  --text-muted: #8b949e;
  --accent: #f7931a;
  --accent-hover: #e8851a;
  --success: #3fb950;
  --error: #f85149;
  --font-mono: 'SF Mono', 'Cascadia Code', 'Fira Code', monospace;
}

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

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

main {
  max-width: 560px;
  width: 100%;
}

header {
  text-align: center;
  margin-bottom: 2rem;
}

h1 {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--accent);
  font-family: var(--font-mono);
  letter-spacing: -0.02em;
}

.tagline {
  color: var(--text-muted);
  margin-top: 0.5rem;
  font-size: 1.1rem;
}

.description {
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 1.5rem;
  font-size: 0.95rem;
}

section {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 2rem;
  margin-bottom: 1.5rem;
}

textarea {
  width: 100%;
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  resize: vertical;
  margin-bottom: 1rem;
}

textarea:focus {
  outline: none;
  border-color: var(--accent);
}

button {
  display: block;
  width: 100%;
  background: var(--accent);
  color: #000;
  border: none;
  border-radius: 8px;
  padding: 0.875rem;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s;
}

button:hover {
  background: var(--accent-hover);
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.hidden {
  display: none !important;
}

.error {
  color: var(--error);
  margin-top: 0.75rem;
  font-size: 0.9rem;
}

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

#qr-container {
  margin: 1rem auto;
  display: inline-block;
  padding: 1rem;
  background: #fff;
  border-radius: 8px;
}

#qr-container canvas {
  display: block;
}

.bolt11-container {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.75rem;
  margin: 1rem 0;
}

.bolt11-container code {
  flex: 1;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  word-break: break-all;
  color: var(--text-muted);
  text-align: left;
  max-height: 3.5em;
  overflow: hidden;
}

.copy-btn {
  width: auto;
  padding: 0.375rem 0.75rem;
  font-size: 0.8rem;
  flex-shrink: 0;
}

.fee-details {
  display: flex;
  justify-content: space-between;
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-top: 0.5rem;
}

.waiting {
  color: var(--text-muted);
  margin-top: 1rem;
  font-size: 0.9rem;
}

.dots::after {
  content: '';
  animation: dots 1.5s steps(4, end) infinite;
}

@keyframes dots {
  0% { content: ''; }
  25% { content: '.'; }
  50% { content: '..'; }
  75% { content: '...'; }
}

.spinner {
  width: 48px;
  height: 48px;
  border: 4px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  margin: 0 auto 1rem;
  animation: spin 0.8s linear infinite;
}

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

.checkmark {
  font-size: 3rem;
  color: var(--success);
  text-align: center;
  margin-bottom: 0.5rem;
}

.error-icon {
  font-size: 3rem;
  color: var(--error);
  text-align: center;
  margin-bottom: 0.5rem;
}

h2 {
  text-align: center;
  margin-bottom: 0.75rem;
  font-size: 1.3rem;
}

a {
  color: var(--accent);
  text-decoration: none;
  display: block;
  text-align: center;
  margin-bottom: 1rem;
  font-family: var(--font-mono);
  font-size: 0.9rem;
}

a:hover {
  text-decoration: underline;
}

footer {
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
  padding: 1rem 0;
  line-height: 1.5;
}

.policy {
  margin-top: 0.5rem;
  font-size: 0.75rem;
  opacity: 0.6;
}

.countdown {
  font-family: var(--font-mono);
  color: var(--accent);
  font-weight: 600;
}

.expired-icon {
  font-size: 3rem;
  text-align: center;
  margin-bottom: 0.5rem;
}

.button-row {
  display: flex;
  gap: 0.5rem;
}

.btn-secondary {
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--border);
  color: var(--text);
}

#state-broadcasting,
#state-success,
#state-error,
#state-expired {
  text-align: center;
}

#state-broadcasting p,
#state-success p,
#state-error p,
#state-expired p {
  color: var(--text-muted);
}

#recent-bumps-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-mono);
  font-size: 0.82rem;
}

#recent-bumps-table th,
#recent-bumps-table td {
  text-align: left;
  padding: 0.4rem 0;
  border-bottom: 1px solid var(--border);
}

#recent-bumps-table th {
  color: var(--text-muted);
  font-weight: 600;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

#recent-bumps-table a {
  display: inline;
  text-align: left;
  word-break: break-all;
}

/* Tx validation checks (live, below textarea) */
.tx-checks {
  margin-bottom: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.check-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
}

.check-icon {
  width: 1.25rem;
  height: 1.25rem;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 700;
  flex-shrink: 0;
  border: 1.5px solid var(--border);
  color: var(--text-muted);
}

.check-pass .check-icon {
  background: color-mix(in srgb, var(--success) 15%, transparent);
  border-color: var(--success);
  color: var(--success);
}

.check-fail .check-icon {
  background: color-mix(in srgb, var(--error) 15%, transparent);
  border-color: var(--error);
  color: var(--error);
}

.check-pending .check-icon {
  background: transparent;
  border-color: var(--border);
  font-size: 0.65rem;
}

.check-label {
  color: var(--text);
}

.check-detail {
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: 0.8em;
}

/* Invoice-state checks (all green, shown above QR) */
.invoice-checks {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  margin-bottom: 1.25rem;
  padding: 0.75rem 1rem;
  background: color-mix(in srgb, var(--success) 8%, transparent);
  border: 1px solid color-mix(in srgb, var(--success) 30%, transparent);
  border-radius: 8px;
}

/* How it works section */
#how-it-works {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 2rem;
  margin-bottom: 1.5rem;
}

#how-it-works h2 {
  margin-bottom: 1.25rem;
}

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

@media (max-width: 480px) {
  .concept-grid {
    grid-template-columns: 1fr;
  }
}

.concept-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
}

.concept-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.5rem;
}

.concept-tag {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent);
  background: color-mix(in srgb, var(--accent) 12%, transparent);
  border: 1px solid color-mix(in srgb, var(--accent) 30%, transparent);
  border-radius: 4px;
  padding: 0.1rem 0.4rem;
}

.bip-link {
  display: inline;
  font-size: 0.78rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  text-align: left;
  margin: 0;
}

.bip-link:hover {
  color: var(--accent);
}

.concept-card p {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.55;
}

.concept-card p em {
  color: var(--text);
  font-style: normal;
}

.concept-card p code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  color: var(--accent);
  background: color-mix(in srgb, var(--accent) 10%, transparent);
  padding: 0.05em 0.3em;
  border-radius: 3px;
}