:root {
  --purple: #5b2af5;
  --purple-dark: #4520c9;
  --ink: #0a0a0a;
  --muted: #6b6b74;
  --bg: #f5f5f7;
  --card-bg: #ffffff;
  --border: #e5e5ea;
  --danger: #d43f3f;
  --success: #1c8a4b;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 32px 16px;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

.card {
  width: 100%;
  max-width: 420px;
  background: var(--card-bg);
  border-radius: 16px;
  box-shadow: 0 4px 24px rgba(10, 10, 10, 0.08);
  padding: 40px 32px;
  text-align: center;
}

.logo {
  height: 32px;
  width: auto;
  margin-bottom: 24px;
}

h1 {
  font-size: 22px;
  font-weight: 700;
  margin: 0 0 4px;
  color: var(--ink);
}

.subtitle {
  margin: 0 0 28px;
  color: var(--muted);
  font-size: 14px;
}

.field {
  text-align: left;
  margin-bottom: 18px;
}

.field label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--muted);
  margin-bottom: 6px;
}

#invoice-number {
  width: 100%;
  padding: 12px 14px;
  font-size: 15px;
  font-weight: 600;
  color: var(--purple);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  letter-spacing: 0.5px;
}

.amount-input {
  display: flex;
  align-items: center;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0 14px;
  background: var(--card-bg);
  transition: border-color 0.15s ease;
}

.amount-input:focus-within {
  border-color: var(--purple);
}

.amount-input .prefix,
.amount-input .suffix {
  color: var(--muted);
  font-size: 15px;
}

.amount-input .suffix {
  font-weight: 600;
}

#amount {
  flex: 1;
  border: none;
  outline: none;
  padding: 12px 8px;
  font-size: 17px;
  font-weight: 600;
  color: var(--ink);
  background: transparent;
}

.hint {
  margin: 6px 2px 0;
  font-size: 12px;
  color: var(--danger);
}

.message {
  margin-bottom: 16px;
  padding: 10px 12px;
  border-radius: 8px;
  font-size: 13px;
  background: #fdecec;
  color: var(--danger);
  text-align: left;
}

#paypal-button-container {
  margin-top: 8px;
  min-height: 45px;
}

#paypal-button-container.disabled {
  opacity: 0.4;
  pointer-events: none;
}

.success-panel {
  text-align: center;
  padding-top: 8px;
}

.success-icon {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: #e6f6ed;
  color: var(--success);
  font-size: 28px;
  line-height: 56px;
  margin: 0 auto 16px;
}

.success-panel h2 {
  font-size: 20px;
  margin: 0 0 20px;
  color: var(--ink);
}

.success-details {
  text-align: left;
  margin: 0;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 8px 16px;
}

.success-details dt {
  font-size: 13px;
  color: var(--muted);
  font-weight: 600;
}

.success-details dd {
  margin: 0;
  font-size: 13px;
  color: var(--ink);
  word-break: break-all;
  text-align: right;
}

@media (max-width: 480px) {
  .card {
    padding: 32px 20px;
    border-radius: 12px;
  }
}