:root {
  --primary: #0077b6;
  --primary-dark: #023e8a;
  --accent: #00b4d8;
  --bg: #f4f9fc;
  --surface: #ffffff;
  --text: #1d2d3a;
  --muted: #5b6b78;
  --border: #dbe7ef;
  --warning-bg: #fff6e5;
  --warning-border: #f4a261;
  --success: #2a9d8f;
  --radius: 10px;
  --header-h: 64px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 16px);
}

body {
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

main {
  flex: 1;
}

a {
  color: var(--primary);
}

.container {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 16px;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  height: var(--header-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  font-size: 1.3rem;
  font-weight: 700;
  text-decoration: none;
  color: var(--primary-dark);
}

.logo img {
  display: block;
  height: 52px;
  width: auto;
}

.site-nav {
  display: flex;
  gap: 24px;
}

.site-nav a {
  text-decoration: none;
  color: var(--muted);
  font-weight: 500;
}

.site-nav a:hover,
.site-nav a.active {
  color: var(--primary);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text);
}

.hero {
  background: linear-gradient(135deg, var(--primary-dark), var(--accent));
  color: #fff;
  padding: 72px 0;
}

.hero-inner {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 48px;
  align-items: center;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  line-height: 1.15;
  margin-bottom: 16px;
}

.hero p {
  font-size: 1.1rem;
  opacity: 0.92;
  margin-bottom: 28px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.btn {
  display: inline-block;
  background: #fff;
  color: var(--primary-dark);
  border: 2px solid #fff;
  padding: 10px 26px;
  border-radius: 999px;
  font-weight: 600;
  text-decoration: none;
  transition: transform 0.15s ease;
}

.btn:hover {
  transform: translateY(-2px);
}

.btn-outline {
  background: transparent;
  color: #fff;
}

.feeder-diagram {
  display: block;
  width: 100%;
  height: auto;
  overflow: visible;
}

.feeder-diagram .outline {
  fill: none;
  stroke: rgba(255, 255, 255, 0.9);
  stroke-width: 2;
  stroke-linejoin: round;
}

.feeder-diagram .outline .food {
  fill: rgba(233, 196, 106, 0.85);
  stroke: none;
}

.feeder-diagram .wire {
  stroke-width: 1.5;
  stroke-dasharray: 4 3;
}

.feeder-diagram .water {
  fill: rgba(255, 255, 255, 0.12);
}

.feeder-diagram .wave {
  fill: none;
  stroke: rgba(255, 255, 255, 0.55);
  stroke-width: 1.5;
}

.feeder-diagram .callouts {
  fill: none;
  stroke: rgba(255, 255, 255, 0.55);
  stroke-width: 1;
  stroke-dasharray: 3 3;
}

.feeder-diagram .labels {
  font-size: 13px;
  fill: rgba(255, 255, 255, 0.85);
}

.feeder-diagram .label-strong {
  font-weight: 600;
  fill: #fff;
}

.feeder-diagram .gate,
.feeder-diagram .servo-arm {
  stroke: #fff;
  stroke-width: 3;
  stroke-linecap: round;
  transform-box: view-box;
  animation: gate 5s ease-in-out infinite;
}

.feeder-diagram .gate {
  transform-origin: 190px 132px;
}

.feeder-diagram .servo-arm {
  transform-origin: 276px 96px;
}

.feeder-diagram .led {
  fill: rgba(255, 255, 255, 0.3);
  animation: led 5s step-end infinite;
}

.feeder-diagram .pellets circle {
  fill: #e9c46a;
  opacity: 0;
  animation: pellet 5s ease-in infinite;
}

.feeder-diagram .pellets circle:nth-child(2) { --dx: -10px; animation-delay: 0.15s; }
.feeder-diagram .pellets circle:nth-child(3) { --dx: 9px; animation-delay: 0.3s; }
.feeder-diagram .pellets circle:nth-child(4) { --dx: -3px; animation-delay: 0.45s; }

.fish-yellow { fill: #ffd166; }
.fish-orange { fill: #ff9f68; }

.fish-flip .eye {
  fill: var(--primary-dark);
}

.fish-swim {
  animation: swim 12s ease-in-out infinite;
}

.fish-swim-2 {
  animation-duration: 15s;
  animation-delay: -7s;
}

.fish-flip {
  transform-box: fill-box;
  transform-origin: center;
  animation: flip 12s ease-in-out infinite;
}

.fish-swim-2 .fish-flip {
  animation-duration: 15s;
  animation-delay: -7s;
}

@keyframes gate {
  0%, 8% { transform: rotate(0deg); }
  14%, 38% { transform: rotate(65deg); }
  46%, 100% { transform: rotate(0deg); }
}

@keyframes led {
  0% { fill: rgba(255, 255, 255, 0.3); }
  10% { fill: #7cfc9a; }
  42% { fill: rgba(255, 255, 255, 0.3); }
}

@keyframes pellet {
  0%, 12% { opacity: 0; transform: translate(0, 0); }
  14% { opacity: 1; transform: translate(0, 0); }
  26% { opacity: 1; transform: translate(calc(var(--dx, 4px) * 0.5), 44px); }
  70% { opacity: 1; transform: translate(var(--dx, 4px), 100px); }
  85%, 100% { opacity: 0; transform: translate(var(--dx, 4px), 120px); }
}

@keyframes swim {
  0% { transform: translateX(0); }
  47%, 50% { transform: translateX(210px); }
  97%, 100% { transform: translateX(0); }
}

@keyframes flip {
  0%, 47% { transform: scaleX(1); }
  50%, 97% { transform: scaleX(-1); }
  100% { transform: scaleX(1); }
}

@media (prefers-reduced-motion: reduce) {
  .feeder-diagram *,
  .fish-swim,
  .fish-flip {
    animation: none !important;
  }
}

.features {
  padding: 64px 0;
}

.features h2 {
  text-align: center;
  margin-bottom: 32px;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 24px;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-top: 3px solid var(--primary);
  border-radius: var(--radius);
  padding: 24px;
}

.card h3 {
  color: var(--primary-dark);
  margin-bottom: 8px;
}

.card p {
  color: var(--muted);
}

.manual {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 40px;
  padding-top: 40px;
  padding-bottom: 64px;
}

.toc {
  position: sticky;
  top: calc(var(--header-h) + 24px);
  align-self: start;
}

.toc h2 {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
  margin-bottom: 12px;
}

.toc ul {
  list-style: none;
  border-left: 2px solid var(--border);
}

.toc li a {
  display: block;
  padding: 6px 14px;
  margin-left: -2px;
  border-left: 2px solid transparent;
  text-decoration: none;
  color: var(--muted);
}

.toc li a:hover,
.toc li a.active {
  color: var(--primary);
  border-left-color: var(--primary);
}

.toc-download {
  display: inline-block;
  margin-top: 20px;
  font-size: 0.9rem;
  font-weight: 600;
}

.info-section {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  margin-bottom: 24px;
}

.info-section h2 {
  color: var(--primary-dark);
  margin-bottom: 16px;
}

.info-section h3 {
  font-size: 1rem;
  margin: 16px 0 8px;
}

.info-section ul {
  padding-left: 22px;
}

.info-section li + li {
  margin-top: 6px;
}

.info-section.warning {
  background: var(--warning-bg);
  border-color: var(--warning-border);
  border-left-width: 5px;
}

.note {
  margin-top: 16px;
  font-style: italic;
  color: var(--muted);
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  list-style: none;
  padding-left: 0 !important;
}

.tags li {
  margin: 0 !important;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 6px 14px;
  font-size: 0.95rem;
}

.accordion-item {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.accordion-item + .accordion-item {
  margin-top: 10px;
}

.accordion-trigger {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 14px 18px;
  background: var(--bg);
  border: none;
  font: inherit;
  font-weight: 600;
  text-align: left;
  color: var(--text);
  cursor: pointer;
}

.accordion-trigger::before {
  content: "Problem:";
  color: var(--primary);
  flex-shrink: 0;
}

.accordion-trigger::after {
  content: "+";
  margin-left: auto;
  font-size: 1.3rem;
  line-height: 1;
  flex-shrink: 0;
}

.accordion-trigger[aria-expanded="true"]::after {
  content: "−";
}

.accordion-panel {
  display: none;
  padding: 14px 18px;
}

.accordion-panel::before {
  content: "Solution: ";
  font-weight: 600;
  color: var(--success);
}

.accordion-panel p {
  display: inline;
}

.accordion-item.open .accordion-panel {
  display: block;
}

.site-footer {
  background: var(--primary-dark);
  color: rgba(255, 255, 255, 0.85);
  padding: 24px 0;
  text-align: center;
  font-size: 0.9rem;
}

@media (max-width: 768px) {
  .nav-toggle {
    display: block;
  }

  .site-nav {
    display: none;
    position: absolute;
    top: var(--header-h);
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background: var(--surface);
    border-bottom: 1px solid var(--border);
  }

  .site-nav.open {
    display: flex;
  }

  .site-nav a {
    padding: 14px 16px;
  }

  .hero {
    padding: 48px 0;
  }

  .hero-inner,
  .manual {
    grid-template-columns: 1fr;
  }

  .toc {
    position: static;
  }

  .info-section {
    padding: 20px;
  }
}