:root {
  --bg: #f5f1e8;
  --panel: #fffdf8;
  --line: #ded8cb;
  --text: #1f231e;
  --muted: #646b61;
  --accent: #1f231e;
  --success: #2c6a55;
  --warning: #8d5e14;
  --error: #a0352f;
  --radius: 20px;
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.5 system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

button,
input {
  font: inherit;
}

.shell {
  width: min(calc(100% - 32px), 760px);
  margin: 0 auto;
  padding: 40px 0 64px;
}

.title,
.receipt-title {
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
  letter-spacing: -0.04em;
}

.title {
  margin-bottom: 20px;
  font-size: clamp(2.4rem, 5vw, 4rem);
}

.receipt-title {
  font-size: clamp(1.5rem, 3vw, 2rem);
}

.panel {
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: 0 18px 40px rgba(31, 35, 30, 0.08);
}

.step {
  display: grid;
  gap: 16px;
}

.amount-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.amount-option,
.primary-button,
.ghost-button {
  min-height: 50px;
  border: 1px solid var(--line);
  border-radius: 14px;
}

.amount-option {
  background: #fff;
  color: var(--text);
  cursor: pointer;
}

.amount-option.is-selected {
  border-color: var(--text);
  background: #f1ece2;
}

.field {
  display: grid;
  gap: 8px;
}

.field span,
.summary span,
.receipt-row span {
  color: var(--muted);
}

input {
  min-height: 50px;
  padding: 0 14px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: #fff;
  color: var(--text);
}

input:disabled {
  background: #f2eee5;
}

.summary,
.receipt {
  display: grid;
  gap: 12px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: #faf7f1;
}

.summary,
.receipt-row,
.toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.message {
  margin: 0;
  color: var(--error);
}

.message[hidden] {
  display: none !important;
}

.message[data-tone="neutral"] {
  color: var(--muted);
}

.message[data-tone="success"] {
  color: var(--success);
}

.message[data-tone="warning"] {
  color: var(--warning);
}

.message[data-tone="error"] {
  color: var(--error);
}

.message.is-muted {
  color: var(--muted);
}

.primary-button,
.ghost-button {
  padding: 0 18px;
  cursor: pointer;
}

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

.primary-button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.ghost-button {
  background: #fff;
  color: var(--text);
}

.checkout-container {
  min-height: 440px;
  padding: 8px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: #fff;
  overflow: hidden;
}

@media (max-width: 640px) {
  .shell {
    width: min(calc(100% - 20px), 760px);
    padding-top: 24px;
  }

  .panel {
    padding: 18px;
  }

  .amount-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 460px) {
  .amount-grid {
    grid-template-columns: 1fr;
  }

  .summary,
  .receipt-row,
  .toolbar {
    flex-direction: column;
    align-items: flex-start;
  }
}