:root {
  --bg: #0d0d0d;
  --bg-card: #1a1a1a;
  --bg-input: #222;
  --border: #333;
  --text: #e0e0e0;
  --text-muted: #888;
  --accent: #ff6600;
  --accent-hover: #ff8533;
  --success: #4caf50;
  --error: #f44336;
  --radius: 8px;
  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --mono: 'JetBrains Mono', 'Fira Code', monospace;
}

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

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
}

header {
  text-align: center;
  padding: 2rem 1rem 1rem;
}

.lang-picker {
  position: fixed;
  top: 0.75rem;
  right: 0.75rem;
  z-index: 50;
}

.lang-toggle {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-muted);
  padding: 0.35rem 0.6rem;
  border-radius: var(--radius);
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
  font-family: var(--font);
  transition: border-color 0.2s, color 0.2s;
}

.lang-toggle:hover,
.lang-picker.open .lang-toggle {
  border-color: var(--accent);
  color: var(--text);
}

.lang-dropdown {
  display: none;
  position: absolute;
  top: calc(100% + 4px);
  right: 0;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  min-width: 120px;
  box-shadow: 0 8px 24px rgba(0,0,0,0.4);
}

.lang-picker.open .lang-dropdown {
  display: block;
}

.lang-option {
  display: block;
  width: 100%;
  padding: 0.5rem 0.75rem;
  background: none;
  border: none;
  color: var(--text-muted);
  font-family: var(--font);
  font-size: 0.8rem;
  text-align: left;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}

.lang-option:hover {
  background: var(--bg-input);
  color: var(--text);
}

.lang-option.active {
  color: var(--accent);
}

header h1 {
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: -0.5px;
}

header h1 a {
  color: inherit;
  text-decoration: none;
}

header h1 a:hover {
  opacity: 0.8;
}

header h1 span {
  color: var(--accent);
}

header p {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-top: 0.3rem;
}

main {
  width: 100%;
  max-width: 480px;
  padding: 1rem;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1rem;
}

label {
  display: block;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.3rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

input, select, textarea {
  width: 100%;
  padding: 0.7rem 0.8rem;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font-family: var(--mono);
  font-size: 0.9rem;
  outline: none;
  transition: border-color 0.2s;
  color-scheme: dark;
}

input[type="number"] {
  -webkit-appearance: none;
  -moz-appearance: textfield;
}

input:-webkit-autofill,
input:-webkit-autofill:hover,
input:-webkit-autofill:focus,
select:-webkit-autofill,
textarea:-webkit-autofill {
  -webkit-box-shadow: 0 0 0 1000px var(--bg-input) inset !important;
  -webkit-text-fill-color: var(--text) !important;
  transition: background-color 5000s ease-in-out 0s;
}

select {
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23888' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.6rem center;
  padding-right: 2rem;
}

input:focus, select:focus, textarea:focus {
  border-color: var(--accent);
}

input.invalid {
  border-color: var(--error);
}

input.valid {
  border-color: var(--success);
}

.field {
  margin-bottom: 1rem;
}

.field:last-child {
  margin-bottom: 0;
}

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

.amount-row input {
  flex: 1;
}

.amount-row select {
  width: 90px;
  flex-shrink: 0;
}

.fiat-hint {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.3rem;
  min-height: 1.1em;
}

.fiat-hint.error {
  color: var(--error);
}

textarea {
  resize: vertical;
  min-height: 60px;
}

.btn {
  width: 100%;
  padding: 0.8rem;
  border: none;
  border-radius: var(--radius);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s, opacity 0.2s;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

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

.btn-primary:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.btn-secondary {
  background: var(--bg-input);
  color: var(--text);
  border: 1px solid var(--border);
  font-size: 0.85rem;
  padding: 0.6rem;
  text-decoration: none;
  text-align: center;
}

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

#result {
  display: none;
}

#result.visible {
  display: block;
}

.qr-container {
  display: flex;
  justify-content: center;
  padding: 1rem 0;
}

.qr-container canvas,
.qr-container img {
  border-radius: var(--radius);
  padding: 12px;
  background: #fff;
  cursor: pointer;
  transition: opacity 0.2s;
}

.qr-container canvas:hover,
.qr-container img:hover {
  opacity: 0.85;
}

.qr-hint {
  text-align: center;
  font-size: 0.7rem;
  color: var(--text-muted);
  margin-top: 0.3rem;
}

.uri-box {
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.6rem 0.8rem;
  font-family: var(--mono);
  font-size: 0.75rem;
  word-break: break-all;
  color: var(--text-muted);
  margin-bottom: 0.8rem;
  max-height: 80px;
  overflow-y: auto;
}

.share-link-box {
  margin-bottom: 0.8rem;
}

.share-link-box label {
  margin-bottom: 0.3rem;
}

.share-link-row {
  display: flex;
  gap: 0.4rem;
}

.share-link-row input {
  flex: 1;
  font-size: 0.75rem;
  padding: 0.5rem 0.6rem;
  cursor: text;
}

.btn-icon {
  width: auto;
  padding: 0.5rem 0.6rem;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

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

.actions .btn-secondary {
  flex: 1;
}

.btn-new {
  margin-top: 0.8rem;
  background: transparent;
  border: 1px solid var(--accent);
  color: var(--accent);
}

.btn-new:hover {
  background: var(--accent);
  color: #fff;
}

.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--success);
  color: #fff;
  padding: 0.6rem 1.2rem;
  border-radius: var(--radius);
  font-size: 0.85rem;
  font-weight: 500;
  opacity: 0;
  transition: transform 0.3s, opacity 0.3s;
  z-index: 100;
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

footer {
  text-align: center;
  padding: 2rem 1rem;
  color: var(--text-muted);
  font-size: 0.75rem;
}

footer a {
  color: var(--accent);
  text-decoration: none;
}

footer a:hover {
  text-decoration: underline;
}

.countdown {
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 0.8rem;
}

.countdown.expired {
  color: var(--error);
}

.countdown.active {
  color: var(--accent);
}

@media (max-width: 500px) {
  main {
    padding: 0.5rem;
  }
  .card {
    padding: 1rem;
  }
  header h1 {
    font-size: 1.5rem;
  }
}