:root {
  --bg: #ffffff;
  --surface: #fafafa;
  --border: #e5e7eb;
  --text: #24292f;
  --text-secondary: #656d76;
  --text-muted: #9ca3af;
  --accent: #007d9c;
  --accent-hover: #006a85;
  --accent-light: #e6f6fa;
  --accent-text: #ffffff;
  --green: #1a7f37;
  --radius: 12px;
  --radius-sm: 8px;
  --radius-pill: 999px;
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --font: system-ui, -apple-system, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --font-mono: 'SF Mono', SFMono-Regular, ui-monospace, Menlo, Consolas, monospace;
}

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

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 1.5rem;
  width: 100%;
}

/* ── Navbar ── */
.navbar {
  border-bottom: 1px solid var(--border);
  padding: 0.75rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
  background: rgba(255,255,255,0.92);
}

.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text);
  text-decoration: none;
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: -0.02em;
}

.logo-gopher {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  object-fit: cover;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 1.75rem;
  align-items: center;
}

.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  transition: color 0.15s;
}

.nav-links a:hover { color: var(--text); }

.nav-links .github-link {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  background: var(--accent);
  color: var(--accent-text);
  border: 1.5px solid var(--accent);
  padding: 0.425rem 1rem;
  border-radius: var(--radius-pill);
  font-size: 0.8125rem;
  font-weight: 600;
  transition: background 0.15s, transform 0.15s;
}

.nav-links .github-link:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
  color: var(--accent-text);
  transform: translateY(-1px);
}

/* ── Hero ── */
.hero {
  text-align: center;
  padding: 3.5rem 0 2.5rem;
}

.hero-gopher {
  margin-bottom: 1.25rem;
}

.gopher-img {
  width: 120px;
  height: auto;
  animation: float 3s ease-in-out infinite;
  filter: drop-shadow(0 8px 16px rgba(0,125,156,0.15));
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

.hero h1 {
  font-size: 2.75rem;
  font-weight: 800;
  letter-spacing: -0.035em;
  line-height: 1.1;
  margin-bottom: 0.75rem;
}

.hero h1 .highlight {
  color: var(--accent-text);
  background: var(--accent);
  padding: 0 0.3em;
  border-radius: 6px;
  display: inline-block;
}

.hero p {
  color: var(--text-secondary);
  font-size: 1.1rem;
  max-width: 520px;
  margin: 0 auto;
  line-height: 1.7;
}

.hero a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

.hero a:hover { text-decoration: underline; }

/* ── Packages section ── */
.packages { padding: 0.5rem 0 3rem; }

.packages h2 {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

/* ── Home cards ── */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
}

.card {
  background: var(--bg);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  text-decoration: none;
  color: var(--text);
  transition: border-color 0.2s, box-shadow 0.2s, transform 0.2s;
}

.card:hover {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent), var(--shadow-md);
  transform: translateY(-2px);
}

.card h3 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.375rem;
}

.card p {
  color: var(--text-secondary);
  font-size: 0.875rem;
  line-height: 1.6;
}

/* ── Utility cards (collapsible) ── */
.util-card {
  border: 2px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 0.75rem;
  overflow: hidden;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.util-card:hover {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent);
}

.util-card.active {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent);
}

.util-card.active .util-card-header {
  background: var(--accent);
}

.util-card.active .util-card-header-left h3,
.util-card.active .util-card-header-left p,
.util-card.active .util-card-chevron {
  color: var(--accent-text);
}

.util-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.25rem;
  cursor: pointer;
  user-select: none;
  transition: background 0.2s;
}

.util-card-header:hover {
  background: var(--accent-light);
}

.util-card.active .util-card-header:hover {
  background: var(--accent-hover);
}

.util-card-header-left h3 {
  font-size: 0.9375rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  margin-bottom: 0.125rem;
}

.util-card-header-left p {
  color: var(--text-secondary);
  font-size: 0.8125rem;
  line-height: 1.4;
}

.util-card-chevron {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  color: var(--text-muted);
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.util-card.active .util-card-chevron {
  transform: rotate(180deg);
}

/* Card body: animated via JS height/opacity, display managed by .active */
.util-card-body {
  padding: 0 1.25rem 1.25rem;
  border-top: 1px solid var(--border);
  overflow: hidden;
  transition: height 0.3s cubic-bezier(0.4, 0, 0.2, 1),
              opacity 0.25s ease;
}

/* Hidden by default, shown when .active is added by JS */
.util-card:not(.active) .util-card-body {
  display: none;
}

.go-signature {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.5rem 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.775rem;
  color: var(--green);
  margin: 0.875rem 0;
  overflow-x: auto;
}

/* ── Forms ── */
label {
  display: block;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 0.25rem;
}

input[type="text"],
input[type="number"],
textarea {
  width: 100%;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.5rem 0.75rem;
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  margin-bottom: 0.625rem;
  outline: none;
  transition: border-color 0.15s, box-shadow 0.15s;
}

input:focus, textarea:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(0,125,156,0.12);
}

input::placeholder { color: var(--text-muted); }

/* ── Buttons ── */
.btn-row {
  display: flex;
  gap: 0.5rem;
  margin-top: 0.25rem;
  margin-bottom: 0.5rem;
}

button, .btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.375rem;
  border: none;
  border-radius: var(--radius-pill);
  padding: 0.5rem 1.25rem;
  font-family: var(--font);
  font-size: 0.8125rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, box-shadow 0.15s, transform 0.15s;
}

button {
  background: var(--accent);
  color: var(--accent-text);
  border: 1.5px solid var(--accent);
}

button:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
  transform: translateY(-1px);
}

button:active {
  transform: translateY(0);
}

button.btn-secondary {
  background: var(--bg);
  color: var(--text);
  border: 1.5px solid var(--border);
}

button.btn-secondary:hover {
  background: var(--surface);
  border-color: var(--accent);
  transform: translateY(-1px);
}

/* ── Output ── */
.output {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.625rem 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--green);
  margin-top: 0.5rem;
  min-height: 2.25rem;
  white-space: pre-wrap;
  word-break: break-all;
  line-height: 1.5;
}

.output:empty::before {
  content: 'Output will appear here...';
  color: var(--text-muted);
  font-style: italic;
}

/* ── Terminal ── */
.terminal-section {
  padding: 0 0 2rem;
  max-width: 640px;
  margin: 0 auto;
}

.terminal {
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 8px 30px rgba(0,0,0,0.12);
  border: 1px solid #2d333b;
}

.terminal-header {
  background: #2d333b;
  padding: 0.625rem 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.terminal-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
}

.terminal-dot.red { background: #ff5f57; }
.terminal-dot.yellow { background: #febc2e; }
.terminal-dot.green { background: #28c840; }

.terminal-title {
  color: #768390;
  font-size: 0.75rem;
  font-family: var(--font-mono);
  margin-left: 0.5rem;
}

.terminal-body {
  background: #1c2128;
  padding: 1rem 1.25rem;
  min-height: 100px;
}

.terminal-line {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  line-height: 1.7;
  color: #adbac7;
}

.terminal-prompt {
  color: #57ab5a;
  margin-right: 0.5rem;
  font-weight: 700;
}

.terminal-typed {
  color: #adbac7;
}

.terminal-cursor {
  color: #57ab5a;
  animation: blink 0.8s step-end infinite;
  font-weight: 300;
}

@keyframes blink {
  50% { opacity: 0; }
}

.terminal-output {
  color: #768390;
  white-space: pre-wrap;
  margin-top: 0.25rem;
  transition: opacity 0.3s ease;
}

/* ── Gophers Banner (Home) ── */
.gophers-banner {
  padding: 0.5rem 0 2rem;
}

.gophers-banner-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.5rem 2rem;
  background: var(--accent-light);
  border: 2px solid var(--accent);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--text);
  transition: box-shadow 0.2s, transform 0.2s;
}

.gophers-banner-inner:hover {
  box-shadow: 0 0 0 2px var(--accent), var(--shadow-md);
  transform: translateY(-2px);
}

.gophers-banner-text h2 {
  font-size: 1.125rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.125rem;
}

.gophers-banner-text p {
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.gophers-banner-arrow {
  font-size: 1.5rem;
  color: var(--accent);
  transition: transform 0.2s;
}

.gophers-banner-inner:hover .gophers-banner-arrow {
  transform: translateX(4px);
}

/* ── Animations ── */

/* Animation-ready: JS adds .animate-ready to <html>, then IntersectionObserver adds .visible */
.animate-ready .fade-in {
  opacity: 0;
  transition: opacity 0.6s ease;
}

.animate-ready .fade-in.visible {
  opacity: 1;
}

.animate-ready .fade-in-up {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.animate-ready .fade-in-up.visible {
  opacity: 1;
  transform: translateY(0);
}

.animate-ready .stagger {
  opacity: 0;
  transform: translateY(16px);
  animation: none;
}

.animate-ready .stagger.visible {
  animation: staggerIn 0.4s ease forwards;
}

@keyframes staggerIn {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Output flash when value changes */
.output-flash {
  animation: flashGreen 0.4s ease;
}

@keyframes flashGreen {
  0% { background: var(--accent-light); }
  100% { background: var(--surface); }
}

/* ── Footer ── */
.footer {
  margin-top: auto;
  border-top: 1px solid var(--border);
  padding: 1.5rem 0;
  text-align: center;
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.footer a {
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 500;
}

.footer a:hover { color: var(--text); }

/* ── Main ── */
main {
  flex: 1;
  padding: 2rem 0;
}

main > h1 {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 1.25rem;
}

/* ── Responsive ── */
@media (max-width: 640px) {
  .hero h1 { font-size: 2rem; }
  .hero p { font-size: 0.95rem; }
  .hero { padding: 3rem 0 2rem; }
  .gopher-img { width: 90px; }
  .nav-links { gap: 1rem; }
  .container { padding: 0 1rem; }
  .util-card-header { padding: 0.875rem 1rem; }
  .util-card-body { padding: 0 1rem 1rem; }
  .terminal-body { font-size: 0.7rem; }
  .gophers-banner-inner { padding: 1.25rem 1.5rem; }
}

/* Reduce motion for accessibility */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
  .gopher-img { animation: none; }
}