/* ==========================================================================
   PyTutor SG — design tokens
   Palette drawn from the Python logo (blue + yellow), set against a cool,
   neutral base so the accents stay legible and don't fight each other.
   ========================================================================== */
:root {
  /* Color */
  --bg: #f7f9fc;
  --surface: #ffffff;
  --surface-2: #eef2f7;
  --ink: #12232e;
  --ink-soft: #4a5d6b;
  --ink-faint: #7c8b96;
  --line: #dbe3ea;

  --py-blue: #306998;
  --py-blue-deep: #1e4c6e;
  --py-blue-soft: #e7f0f7;
  --py-yellow: #ffd43b;
  --py-yellow-deep: #b8860b;

  --success: #1c7a4d;
  --error: #c23a3a;

  /* Type */
  --font-display: "Space Grotesk", "Inter", sans-serif;
  --font-body: "Inter", -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;

  /* Layout */
  --wrap: 1180px;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 22px;
  --shadow-sm: 0 1px 2px rgba(18, 35, 46, 0.06);
  --shadow-md: 0 8px 24px rgba(18, 35, 46, 0.08);
  --shadow-lg: 0 24px 60px rgba(18, 35, 46, 0.14);

  --header-h: 76px;
}

/* ==========================================================================
   Reset
   ========================================================================== */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: var(--header-h); }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; display: block; }
a { color: inherit; }
button { font: inherit; }
ul, ol { padding: 0; margin: 0; list-style: none; }
h1, h2, h3, p { margin: 0; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--py-blue-deep);
  color: #fff;
  padding: 12px 18px;
  z-index: 200;
  border-radius: 0 0 8px 0;
}
.skip-link:focus {
  left: 0;
}

:focus-visible {
  outline: 3px solid var(--py-blue);
  outline-offset: 2px;
  border-radius: 4px;
}

.wrap {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 24px;
}

/* ==========================================================================
   Header / nav
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-h);
  display: flex;
  align-items: center;
  background: rgba(247, 249, 252, 0.85);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--line);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.15rem;
  color: var(--ink);
}
.brand-mark {
  font-family: var(--font-mono);
  background: var(--py-blue-deep);
  color: var(--py-yellow);
  border-radius: 8px;
  padding: 5px 8px;
  font-size: 0.85rem;
  font-weight: 600;
  line-height: 1;
}
.brand-dot { color: var(--py-blue); }

.main-nav {
  display: flex;
  align-items: center;
  gap: 28px;
  font-size: 0.95rem;
  font-weight: 500;
}
.main-nav a {
  text-decoration: none;
  color: var(--ink-soft);
  position: relative;
  padding: 6px 0;
  transition: color 0.15s ease;
}
.main-nav a:not(.nav-cta):hover { color: var(--ink); }
.main-nav a:not(.nav-cta)::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -2px;
  height: 2px;
  background: var(--py-yellow);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.2s ease;
}
.main-nav a:not(.nav-cta):hover::after { transform: scaleX(1); }

.nav-cta {
  background: var(--py-blue-deep);
  color: #fff !important;
  padding: 9px 18px;
  border-radius: 999px;
  font-weight: 600;
  transition: background 0.15s ease, transform 0.15s ease;
}
.nav-cta:hover { background: var(--py-blue); transform: translateY(-1px); }

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  background: none;
  border: none;
  cursor: pointer;
  border-radius: 8px;
}
.nav-toggle span {
  display: block;
  height: 2px;
  width: 22px;
  margin: 0 auto;
  background: var(--ink);
  transition: transform 0.2s ease, opacity 0.2s ease;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ==========================================================================
   Buttons
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 24px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  border: 1.5px solid transparent;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease, color 0.15s ease;
}
.btn-primary {
  background: var(--py-yellow);
  color: var(--py-blue-deep);
  box-shadow: var(--shadow-sm);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }
.btn-ghost {
  background: transparent;
  color: var(--ink);
  border-color: var(--line);
}
.btn-ghost:hover { border-color: var(--py-blue); color: var(--py-blue-deep); }
.btn-outline {
  background: transparent;
  color: var(--py-blue-deep);
  border-color: var(--py-blue-deep);
}
.btn-outline:hover { background: var(--py-blue-deep); color: #fff; }
.btn-block { width: 100%; }
.btn:disabled { opacity: 0.6; cursor: not-allowed; transform: none !important; }

/* ==========================================================================
   Hero
   ========================================================================== */
.hero {
  padding: 72px 0 96px;
  background:
    radial-gradient(700px 380px at 85% -10%, rgba(255, 212, 59, 0.25), transparent 60%),
    radial-gradient(900px 500px at -10% 20%, rgba(48, 105, 152, 0.10), transparent 60%);
}
.hero-grid {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 56px;
  align-items: center;
}
.eyebrow {
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 0.78rem;
  color: var(--py-blue-deep);
  font-weight: 600;
  margin-bottom: 14px;
}
.hero-copy h1 {
  font-family: var(--font-display);
  font-size: clamp(2.2rem, 4.4vw, 3.4rem);
  line-height: 1.12;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--ink);
}
.hero-copy h1 .hl {
  color: var(--py-blue-deep);
  position: relative;
  white-space: nowrap;
}
.hero-copy h1 .hl::after {
  content: "";
  position: absolute;
  left: -2%;
  right: -2%;
  bottom: 4px;
  height: 0.32em;
  background: var(--py-yellow);
  z-index: -1;
  border-radius: 2px;
}
.hero-lede {
  margin-top: 20px;
  font-size: 1.08rem;
  color: var(--ink-soft);
  max-width: 46ch;
}
.hero-actions {
  margin-top: 32px;
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
}
.hero-stats {
  display: flex;
  gap: 32px;
  margin-top: 44px;
  padding-top: 28px;
  border-top: 1px solid var(--line);
}
.hero-stats li { display: flex; flex-direction: column; gap: 2px; }
.hero-stats strong {
  font-family: var(--font-display);
  font-size: 1.4rem;
  color: var(--py-blue-deep);
}
.hero-stats span { font-size: 0.82rem; color: var(--ink-faint); }

/* Terminal (signature element) */
.hero-terminal {
  background: #0f2233;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
  transform: rotate(0.4deg);
}
.terminal-chrome {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 14px 16px;
  background: #0a1a28;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}
.dot { width: 11px; height: 11px; border-radius: 50%; display: inline-block; }
.dot-red { background: #ff5f56; }
.dot-yellow { background: #ffbd2e; }
.dot-green { background: #27c93f; }
.terminal-title {
  margin-left: 8px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: rgba(255, 255, 255, 0.5);
}
.terminal-body {
  margin: 0;
  padding: 24px 22px 30px;
  min-height: 300px;
  font-family: var(--font-mono);
  font-size: 0.92rem;
  line-height: 1.7;
  color: #dce8f0;
  white-space: pre-wrap;
  word-break: break-word;
}
.terminal-body .c-prompt { color: var(--py-yellow); }
.terminal-body .c-out { color: #7fd1a3; }
.terminal-body .c-comment { color: #6f8ba0; }
.terminal-cursor {
  display: inline-block;
  width: 8px;
  height: 1.1em;
  background: var(--py-yellow);
  margin-left: 2px;
  vertical-align: text-bottom;
  animation: blink 1s steps(1) infinite;
}
@keyframes blink { 50% { opacity: 0; } }

/* ==========================================================================
   Sections (shared)
   ========================================================================== */
.section { padding: 88px 0; }
.section-alt { background: var(--surface); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.section h2 {
  font-family: var(--font-display);
  font-size: clamp(1.7rem, 2.8vw, 2.3rem);
  font-weight: 700;
  letter-spacing: -0.01em;
  margin-top: 4px;
  max-width: 20ch;
}
.section-lede {
  margin-top: 16px;
  color: var(--ink-soft);
  max-width: 62ch;
  font-size: 1.02rem;
}

/* Reveal-on-scroll */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity 0.6s ease, transform 0.6s ease; }
.reveal.is-visible { opacity: 1; transform: translateY(0); }

/* ==========================================================================
   Lessons — cards
   ========================================================================== */
.grid-3 {
  margin-top: 44px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 22px;
}
.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 26px 24px;
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: rgba(48,105,152,0.35); }
.card-tag {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--py-blue);
  margin-bottom: 10px;
  font-weight: 600;
}
.card h3 { font-family: var(--font-display); font-size: 1.15rem; margin-bottom: 8px; }
.card p { color: var(--ink-soft); font-size: 0.95rem; }

.callout {
  margin-top: 32px;
  background: var(--py-blue-soft);
  border: 1px solid rgba(48, 105, 152, 0.18);
  border-radius: var(--radius-md);
  padding: 22px 26px;
}
.callout p { color: var(--py-blue-deep); font-size: 0.98rem; }

/* ==========================================================================
   Pricing
   ========================================================================== */
.pricing-grid {
  margin-top: 44px;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
  align-items: stretch;
}
.price-card {
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 32px;
  display: flex;
  flex-direction: column;
}
.price-card-featured {
  background: var(--py-blue-deep);
  color: #fff;
  border-color: var(--py-blue-deep);
  box-shadow: var(--shadow-lg);
  position: relative;
}
.price-card-label {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--py-blue-deep);
}
.price-card-featured .price-card-label { color: var(--py-yellow); }
.badge {
  background: var(--py-yellow);
  color: var(--py-blue-deep);
  font-size: 0.7rem;
  font-weight: 700;
  padding: 3px 9px;
  border-radius: 999px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.price-amount {
  font-family: var(--font-display);
  font-size: 2.6rem;
  font-weight: 700;
  margin-top: 14px;
  letter-spacing: -0.01em;
}
.price-amount span {
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--ink-faint);
  margin-left: 6px;
}
.price-card-featured .price-amount span { color: rgba(255,255,255,0.65); }
.price-sub { margin-top: 6px; color: var(--ink-soft); font-size: 0.92rem; }
.price-card-featured .price-sub { color: rgba(255,255,255,0.8); }

.price-code {
  margin: 22px 0 0;
  background: #0f2233;
  color: #dce8f0;
  border-radius: var(--radius-sm);
  padding: 18px 20px;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.9;
  overflow-x: auto;
}
.price-code .c-comment { color: #7fa2b8; }

.price-features { margin-top: 24px; display: flex; flex-direction: column; gap: 10px; flex: 1; }
.price-features li {
  font-size: 0.92rem;
  padding-left: 22px;
  position: relative;
  color: var(--ink-soft);
}
.price-card-featured .price-features li { color: rgba(255,255,255,0.85); }
.price-features li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: var(--py-blue);
  font-weight: 700;
}
.price-card-featured .price-features li::before { color: var(--py-yellow); }
.price-card .btn { margin-top: 28px; }

/* ==========================================================================
   How it works — steps
   ========================================================================== */
.steps {
  margin-top: 48px;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px 40px;
}
.step { display: flex; gap: 18px; }
.step-num {
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--py-blue);
  background: var(--py-blue-soft);
  width: 42px;
  height: 42px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}
.step h3 { font-family: var(--font-display); font-size: 1.08rem; margin-bottom: 6px; }
.step p { color: var(--ink-soft); font-size: 0.95rem; }

/* ==========================================================================
   Assignment help
   ========================================================================== */
.assignments-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 48px;
  align-items: center;
}
.check-list { margin-top: 22px; display: flex; flex-direction: column; gap: 12px; }
.check-list li {
  padding-left: 26px;
  position: relative;
  color: var(--ink-soft);
  font-size: 0.96rem;
}
.check-list li::before {
  content: "";
  position: absolute;
  left: 0; top: 6px;
  width: 14px; height: 14px;
  border-radius: 4px;
  background: var(--py-yellow);
}
.assignments-grid .btn { margin-top: 28px; }

.mini-terminal {
  background: #0f2233;
  color: #dce8f0;
  border-radius: var(--radius-lg);
  padding: 28px 26px;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 2;
  box-shadow: var(--shadow-lg);
}
.mini-terminal .c-prompt { color: var(--py-yellow); }
.mini-terminal .c-str { color: #f0c674; }
.mini-terminal .c-out { color: #7fd1a3; }
.mini-terminal .c-comment { color: #6f8ba0; }

/* ==========================================================================
   FAQ / accordion
   ========================================================================== */
.accordion { margin-top: 40px; border-top: 1px solid var(--line); }
.accordion-item { border-bottom: 1px solid var(--line); }
.accordion-trigger {
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  padding: 22px 4px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  font-family: var(--font-display);
  font-size: 1.02rem;
  font-weight: 600;
  color: var(--ink);
  cursor: pointer;
}
.accordion-icon {
  flex-shrink: 0;
  width: 22px; height: 22px;
  border-radius: 50%;
  border: 1.5px solid var(--py-blue);
  position: relative;
}
.accordion-icon::before, .accordion-icon::after {
  content: "";
  position: absolute;
  background: var(--py-blue);
  top: 50%; left: 50%;
  transform: translate(-50%, -50%);
}
.accordion-icon::before { width: 10px; height: 1.5px; }
.accordion-icon::after { width: 1.5px; height: 10px; transition: transform 0.2s ease; }
.accordion-trigger[aria-expanded="true"] .accordion-icon::after { transform: translate(-50%, -50%) rotate(90deg) scale(0); }

.accordion-panel {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.25s ease;
}
.accordion-panel p { padding: 0 4px 22px; color: var(--ink-soft); max-width: 62ch; }

/* ==========================================================================
   Contact
   ========================================================================== */
.section-contact { background: var(--surface); border-top: 1px solid var(--line); }
.contact-grid {
  display: grid;
  grid-template-columns: 0.85fr 1.15fr;
  gap: 56px;
}
.contact-form {
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 32px;
  display: flex;
  flex-direction: column;
  gap: 18px;
}
.form-row { display: flex; flex-direction: column; gap: 7px; }
.form-row label { font-size: 0.88rem; font-weight: 600; color: var(--ink); }
.form-row .optional { font-weight: 400; color: var(--ink-faint); }
.form-row input,
.form-row select,
.form-row textarea {
  font: inherit;
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  border: 1.5px solid var(--line);
  background: var(--surface);
  color: var(--ink);
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
  resize: vertical;
}
.form-row input:focus,
.form-row select:focus,
.form-row textarea:focus {
  outline: none;
  border-color: var(--py-blue);
  box-shadow: 0 0 0 4px rgba(48, 105, 152, 0.12);
}
.form-row input:invalid[data-touched="true"],
.form-row textarea:invalid[data-touched="true"] {
  border-color: var(--error);
}
.field-error {
  font-size: 0.82rem;
  color: var(--error);
  min-height: 1em;
}

/* Honeypot — visually hidden but present for real browsers/assistive tech to skip */
.hp-field {
  position: absolute;
  width: 1px; height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

.form-status {
  font-size: 0.92rem;
  min-height: 1.2em;
  font-weight: 500;
}
.form-status[data-state="success"] { color: var(--success); }
.form-status[data-state="error"] { color: var(--error); }

/* ==========================================================================
   Footer
   ========================================================================== */
.site-footer {
  padding: 44px 0;
  background: var(--py-blue-deep);
  color: rgba(255, 255, 255, 0.85);
}
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
}
.brand-footer { color: #fff; }
.brand-footer .brand-mark { background: var(--py-yellow); color: var(--py-blue-deep); }
.brand-footer .brand-dot { color: var(--py-yellow); }
.footer-note { font-size: 0.9rem; color: rgba(255,255,255,0.7); }
.footer-copy { font-size: 0.82rem; color: rgba(255,255,255,0.55); }

/* ==========================================================================
   Responsive
   ========================================================================== */
@media (max-width: 960px) {
  .hero-grid { grid-template-columns: 1fr; }
  .hero-terminal { order: -1; transform: none; }
  .assignments-grid { grid-template-columns: 1fr; }
  .assignments-grid .mini-terminal { order: -1; }
  .contact-grid { grid-template-columns: 1fr; }
  .grid-3 { grid-template-columns: 1fr 1fr; }
  .pricing-grid { grid-template-columns: 1fr; }
  .steps { grid-template-columns: 1fr; }
}

@media (max-width: 760px) {
  :root { --header-h: 64px; }
  .main-nav {
    position: fixed;
    top: var(--header-h);
    left: 0; right: 0;
    background: var(--surface);
    border-bottom: 1px solid var(--line);
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 8px 24px 20px;
    transform: translateY(-8px);
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.18s ease, transform 0.18s ease, visibility 0.18s;
  }
  .main-nav.is-open { opacity: 1; transform: translateY(0); visibility: visible; }
  .main-nav a { padding: 14px 0; border-bottom: 1px solid var(--line); }
  .main-nav a::after { display: none; }
  .nav-cta { margin-top: 12px; text-align: center; }
  .nav-toggle { display: flex; }

  .hero { padding: 44px 0 64px; }
  .hero-stats { gap: 22px; flex-wrap: wrap; }
  .section { padding: 64px 0; }
  .grid-3 { grid-template-columns: 1fr; }
}

@media (max-width: 420px) {
  .wrap { padding: 0 18px; }
  .price-amount { font-size: 2.1rem; }
}