:root {
  --color-red-dark: #780000;
  --color-red-bright: #c1121f;
  --color-beige: #fdf0d5;
  --color-blue-deep: #003049;
  --color-blue-gray: #669bbc;
  --color-white: #ffffff;
  --color-text: #1f2933;
  --border: rgba(0, 48, 73, 0.12);
  --shadow: 0 8px 24px rgba(0, 48, 73, 0.08);
  --radius: 14px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Inter", "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: var(--color-text);
  background: linear-gradient(180deg, var(--color-beige) 0%, #ffffff 72%);
  line-height: 1.6;
}

.app-shell {
  width: min(94%, 1120px);
  margin: 0 auto;
  padding: 2rem 0 3rem;
}

.app-header {
  padding: 2rem 0 1rem;
}

.back-link {
  display: inline-block;
  margin-bottom: 1rem;
  color: var(--color-blue-deep);
  text-decoration-thickness: 2px;
  font-weight: 600;
}

.kicker {
  margin: 0 0 0.25rem;
  color: var(--color-red-bright);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  font-weight: 700;
  font-size: 0.82rem;
}

h1,
h2,
h3 {
  color: var(--color-blue-deep);
  line-height: 1.2;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 5vw, 3.35rem);
}

h2 {
  margin: 0 0 0.8rem;
}

h3 {
  margin: 0.2rem 0 0.55rem;
}

.subtitle {
  max-width: 820px;
  margin-top: 0.75rem;
  color: var(--color-red-dark);
  font-weight: 600;
  font-size: 1.05rem;
}

.panel {
  background: var(--color-white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.15rem;
  box-shadow: var(--shadow);
  margin-top: 1rem;
}

.section-heading p,
.note,
.method-note p {
  color: #52616f;
}

.canvas-wrap {
  width: min(100%, 920px);
  margin: 0 auto;
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: #fff;
}

#gameCanvas {
  display: block;
  width: 100%;
  height: auto;
  background: #fff;
  touch-action: manipulation;
}

.controls {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 1rem;
  align-items: end;
  margin-top: 1rem;
}

.controls label {
  grid-column: span 7;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  font-weight: 700;
  color: var(--color-blue-deep);
}

input {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.72rem 0.8rem;
  font: inherit;
  background: #fff;
  color: var(--color-text);
}

input:focus {
  outline: 3px solid rgba(102, 155, 188, 0.28);
  border-color: var(--color-blue-gray);
}

.button-row {
  grid-column: span 5;
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
}

.btn {
  border: 0;
  cursor: pointer;
  text-decoration: none;
  padding: 0.72rem 1.05rem;
  border-radius: 10px;
  font-weight: 700;
  transition: transform 160ms ease, box-shadow 160ms ease, background-color 160ms ease;
}

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

.btn-outline {
  background: transparent;
  color: var(--color-blue-deep);
  border: 1px solid var(--color-blue-deep);
}

.btn-soft {
  background: var(--color-beige);
  color: var(--color-blue-deep);
  border: 1px solid rgba(0, 48, 73, 0.15);
}

.btn:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.btn:not(:disabled):hover,
.btn:not(:disabled):focus-visible {
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.status-message {
  margin: 1rem 0 0;
  color: #52616f;
  font-weight: 700;
}

.status-message.success {
  color: #0f766e;
}

.status-message.error {
  color: var(--color-red-bright);
}

.status-message code,
.education-card code {
  color: var(--color-red-dark);
  font-weight: 700;
}

.education-grid {
  display: grid;
  gap: 0.85rem;
  margin-top: 1rem;
}

.function-section {
  border: 1px solid var(--border);
  border-radius: 12px;
  background: #fff;
  overflow: hidden;
  box-shadow: 0 5px 18px rgba(0, 48, 73, 0.05);
}

.function-section summary {
  cursor: pointer;
  list-style: none;
  padding: 0.95rem 1rem;
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  align-items: center;
  color: var(--color-blue-deep);
  background: rgba(253, 240, 213, 0.42);
  transition: background-color 160ms ease;
}

.function-section summary::-webkit-details-marker {
  display: none;
}

.function-section summary:hover,
.function-section summary:focus-visible {
  background: rgba(102, 155, 188, 0.16);
  outline: none;
}

.function-section summary strong {
  display: block;
  font-size: 1.05rem;
}

.function-section summary small {
  display: block;
  margin-top: 0.2rem;
  color: #52616f;
  font-weight: 500;
  line-height: 1.4;
}

.summary-indicator {
  flex: 0 0 auto;
  border: 1px solid rgba(0, 48, 73, 0.16);
  border-radius: 999px;
  padding: 0.18rem 0.6rem;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--color-blue-deep);
  background: #fff;
}

.function-section[open] .summary-indicator {
  color: #fff;
  background: var(--color-blue-deep);
}

.function-section[open] .summary-indicator {
  font-size: 0;
}

.function-section[open] .summary-indicator::after {
  content: "Close";
  font-size: 0.82rem;
}

.section-card-grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 1rem;
  padding: 1rem;
  border-top: 1px solid var(--border);
}

.education-card {
  grid-column: span 4;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem;
  background: #fff;
  box-shadow: 0 5px 18px rgba(0, 48, 73, 0.05);
}

.education-card p {
  color: #52616f;
}

.parameter-box {
  margin: 0.8rem 0 0.9rem;
  padding: 0.75rem;
  border: 1px solid rgba(0, 48, 73, 0.1);
  border-radius: 10px;
  background: rgba(253, 240, 213, 0.28);
}

.parameter-box h4 {
  margin: 0 0 0.45rem;
  color: var(--color-blue-deep);
  font-size: 0.95rem;
}

.parameter-box ul {
  margin: 0;
  padding-left: 1.15rem;
}

.parameter-box li {
  margin-bottom: 0.35rem;
  color: #52616f;
  font-size: 0.94rem;
}

.parameter-box li:last-child {
  margin-bottom: 0;
}

.card-canvas {
  width: 100%;
  height: 120px;
  border: 1px solid rgba(0, 48, 73, 0.08);
  border-radius: 10px;
  background: #fff;
}

.copy-row {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  align-items: center;
  margin-top: 0.75rem;
}

.formula {
  display: inline-block;
  margin: 0.4rem 0 0.75rem;
  padding: 0.45rem 0.7rem;
  border-radius: 10px;
  background: rgba(102, 155, 188, 0.12);
  color: var(--color-blue-deep);
  font-family: "Cambria Math", "Times New Roman", serif;
  font-size: 1.05rem;
  font-weight: 700;
}

@media (max-width: 900px) {
  .controls label,
  .button-row,
  .education-card {
    grid-column: span 12;
  }

  .panel {
    padding: 1rem;
  }
}