:root {
  --bg: #111315;
  --surface: #181c20;
  --surface-alt: #1f2429;
  --border: #2c333a;
  --border-strong: #3b444d;
  --text: #f1f3f5;
  --muted: #a7b0b8;
  --primary: #3dd6a6;
  --primary-soft: rgba(61, 214, 166, 0.14);
  --warning: #f0b35b;
  --warning-soft: rgba(240, 179, 91, 0.14);
  --danger: #e67d7d;
  --danger-soft: rgba(230, 125, 125, 0.14);
  --radius: 10px;
  --shadow: 0 4px 16px rgba(0, 0, 0, 0.18);
  --container: 1200px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: "IBM Plex Sans", sans-serif;
  line-height: 1.5;
}

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

img {
  display: block;
  max-width: 100%;
}

button,
input,
textarea {
  font: inherit;
}

button {
  color: inherit;
}

.theme-home {
  min-height: 100vh;
}

.container {
  width: min(var(--container), calc(100% - 32px));
  margin: 0 auto;
}

.site-header {
  border-bottom: 1px solid var(--border);
  background: rgba(17, 19, 21, 0.92);
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(10px);
}

.topbar {
  min-height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.01em;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 20px;
}

.main-nav a {
  color: var(--muted);
  font-size: 0.95rem;
}

.main-nav a:hover,
.main-nav a:focus-visible {
  color: var(--text);
}

.intro-section,
.section {
  padding: 32px 0;
}

.intro-grid,
.split-section,
.validation-grid,
.api-grid,
.contact-grid {
  display: grid;
  gap: 24px;
}

.intro-grid {
  grid-template-columns: minmax(0, 1.3fr) minmax(280px, 0.7fr);
  align-items: start;
  padding-top: 12px;
}

.intro-copy h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3.5rem);
  line-height: 1.08;
  letter-spacing: -0.03em;
}

.lead,
.section-copy,
.contact-status,
.empty-state {
  color: var(--muted);
}

.lead {
  max-width: 66ch;
  margin-top: 16px;
  font-size: 1.05rem;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  padding: 0 16px;
  border: 1px solid transparent;
  border-radius: 8px;
  font-weight: 600;
  cursor: pointer;
  transition: background-color 140ms ease, border-color 140ms ease, color 140ms ease;
}

.button:disabled {
  cursor: wait;
  opacity: 0.7;
}

.button-primary {
  background: var(--primary);
  border-color: var(--primary);
  color: #0b1512;
}

.button-primary:hover,
.button-primary:focus-visible {
  background: #4adfb0;
  border-color: #4adfb0;
}

.button-secondary {
  background: var(--surface);
  border-color: var(--border-strong);
  color: var(--text);
}

.button-secondary:hover,
.button-secondary:focus-visible {
  background: var(--surface-alt);
}

.button-small {
  min-height: 34px;
  padding: 0 12px;
  font-size: 0.88rem;
}

.summary-panel,
.card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow);
}

.summary-panel,
.card {
  padding: 20px;
}

.summary-panel h2,
.section h2,
.card h2,
.card h3 {
  margin: 0;
  font-size: 1.25rem;
  line-height: 1.2;
}

.summary-list,
.details-list {
  display: grid;
  gap: 14px;
  margin: 16px 0 0;
}

.summary-list div,
.details-list div {
  display: grid;
  gap: 4px;
}

.summary-list dt,
.details-list dt,
.contact-form span,
.route-panel-label {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--muted);
}

.summary-list dd,
.details-list dd {
  margin: 0;
}

.mono {
  font-family: "IBM Plex Mono", monospace;
  font-size: 0.92rem;
}

.split-section {
  grid-template-columns: minmax(240px, 0.55fr) minmax(0, 1.45fr);
}

.route-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.route-card,
.layer-card {
  min-height: 100%;
}

.route-card p,
.layer-card p,
.tutorial-list p,
.flow-list,
.empty-state {
  margin-top: 10px;
  color: var(--muted);
}

.section-muted {
  background: #15181b;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.validation-grid {
  grid-template-columns: minmax(0, 1.05fr) minmax(300px, 0.95fr);
}

.chip-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin-top: 20px;
}

.chip {
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  padding: 12px 14px;
  font-size: 0.95rem;
}

.flow-list {
  padding-left: 18px;
}

.flow-list li + li {
  margin-top: 8px;
}

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

.status-header,
.tutorial-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
}

.status-header {
  padding-bottom: 14px;
  border-bottom: 1px solid var(--border);
}

.tutorial-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.status-tag {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  padding: 0 10px;
  border-radius: 8px;
  border: 1px solid var(--border);
  font-size: 0.8rem;
  font-weight: 600;
  white-space: nowrap;
}

.status-info {
  background: var(--primary-soft);
  border-color: rgba(61, 214, 166, 0.26);
  color: var(--primary);
}

.status-ok {
  background: var(--primary-soft);
  border-color: rgba(61, 214, 166, 0.26);
  color: var(--primary);
}

.status-warn {
  background: var(--warning-soft);
  border-color: rgba(240, 179, 91, 0.28);
  color: var(--warning);
}

.status-error {
  background: var(--danger-soft);
  border-color: rgba(230, 125, 125, 0.28);
  color: var(--danger);
}

.tutorial-list {
  display: grid;
  gap: 12px;
  margin-top: 16px;
}

.inner-card {
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface-alt);
  padding: 16px;
}

.tutorial-head span {
  white-space: nowrap;
}

.contact-form {
  display: grid;
  gap: 14px;
}

.contact-form label {
  display: grid;
  gap: 6px;
}

.contact-form span {
  text-transform: none;
  letter-spacing: 0;
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  border: 1px solid var(--border-strong);
  border-radius: 8px;
  padding: 12px 14px;
  background: #121518;
  color: var(--text);
}

.contact-form input:focus,
.contact-form textarea:focus {
  outline: 2px solid rgba(61, 214, 166, 0.22);
  outline-offset: 0;
  border-color: var(--primary);
}

.architecture-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.not-found-shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
}

.not-found-card {
  width: min(520px, 100%);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  padding: 24px;
}

.not-found-card h1 {
  margin: 10px 0 8px;
  font-size: 2.5rem;
}

.not-found-card p {
  color: var(--muted);
}

@media (max-width: 1279px) {
  .route-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 1023px) {
  .intro-grid,
  .split-section,
  .validation-grid,
  .api-grid,
  .contact-grid,
  .architecture-grid {
    grid-template-columns: 1fr;
  }

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

@media (max-width: 767px) {
  .container {
    width: min(100% - 24px, var(--container));
  }

  .topbar,
  .status-header,
  .tutorial-head {
    flex-direction: column;
    align-items: flex-start;
  }

  .tutorial-actions {
    width: 100%;
    justify-content: flex-start;
  }

  .main-nav {
    flex-wrap: wrap;
    gap: 12px 16px;
  }

  .route-grid,
  .chip-grid {
    grid-template-columns: 1fr;
  }

  .button-row {
    flex-direction: column;
  }

  .button {
    width: 100%;
  }
}

/* Tutorial detail page (P0) */
.tutorial-detail {
  max-width: 860px;
  margin: 0 auto;
  padding: 32px 0 48px;
}

.tutorial-detail h1 {
  font-size: 2rem;
  line-height: 1.15;
  margin-bottom: 12px;
}

.tutorial-detail .lead {
  font-size: 1.1rem;
  max-width: 72ch;
}

.tutorial-detail .back-link {
  display: inline-block;
  margin-bottom: 24px;
  color: var(--muted);
  font-size: 0.95rem;
}

.tutorial-detail .tutorial-meta {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin: 16px 0 28px;
  color: var(--muted);
  font-size: 0.95rem;
}

.tutorial-detail .tutorial-meta .meta {
  background: var(--surface-alt);
  border: 1px solid var(--border);
  padding: 4px 10px;
  border-radius: 6px;
}

.tutorial-detail .tutorial-steps {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 20px;
}

.tutorial-detail .tutorial-steps > li {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  padding: 20px;
}

.tutorial-detail .step-header {
  font-size: 1.05rem;
  margin-bottom: 8px;
}

.tutorial-detail .expected-elements {
  margin-top: 12px;
}

.tutorial-detail .expected-elements .chip {
  display: inline-block;
  font-size: 0.8rem;
  padding: 2px 8px;
  margin-right: 6px;
  margin-bottom: 4px;
}

.tutorial-detail .tips {
  margin-top: 12px;
  padding-left: 18px;
  color: var(--muted);
  font-size: 0.92rem;
}