:root {
  /* Moodboard: Deep Navy / Cyan signal / Amber highlight */
  --bg: #0a1628;
  --bg-elev: #0f1d33;
  --panel: #12233c;
  --text: #f4f7fb;
  --muted: #9aabc0;
  --faint: #6b7f96;
  --line: #243652;
  --accent: #ffb800;
  --accent-dim: rgba(255, 184, 0, 0.14);
  --signal: #00d4ff;
  --signal-dim: rgba(0, 212, 255, 0.14);
  --ok: #3ecf8e;
  --bad: #e85d5d;
  --focus: #00d4ff;
  --radius: 10px;
  --font-display: "Space Grotesk", "Avenir Next", sans-serif;
  --font-body: "Manrope", "Avenir Next", sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, monospace;
  --shadow: 0 18px 50px rgba(0, 10, 28, 0.45);
  color-scheme: dark;
}

[data-theme="light"] {
  --bg: #eef3f8;
  --bg-elev: #ffffff;
  --panel: #ffffff;
  --text: #0a1628;
  --muted: #4a5d73;
  --faint: #7a8ea3;
  --line: #d0dae6;
  --accent: #c48a00;
  --accent-dim: rgba(196, 138, 0, 0.12);
  --signal: #008fb3;
  --signal-dim: rgba(0, 143, 179, 0.1);
  --ok: #1f9d62;
  --bad: #c53d3d;
  --focus: #008fb3;
  --shadow: 0 14px 40px rgba(10, 22, 40, 0.08);
  color-scheme: light;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: var(--font-body);
  background:
    radial-gradient(1200px 600px at 10% -10%, rgba(255, 184, 0, 0.09), transparent 55%),
    radial-gradient(900px 500px at 100% 0%, rgba(0, 212, 255, 0.08), transparent 50%),
    linear-gradient(180deg, #0d1c34 0%, var(--bg) 42%);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.55;
}

[data-theme="light"] body {
  background:
    radial-gradient(1000px 500px at 0% 0%, rgba(0, 212, 255, 0.08), transparent 50%),
    linear-gradient(180deg, #e8eef5, var(--bg));
}

a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--text); }

.app-shell {
  max-width: 1080px;
  margin: 0 auto;
  padding: 1.25rem 1.25rem 4rem;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.75rem 0 1.25rem;
  border-bottom: 1px solid var(--line);
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
  cursor: pointer;
}
.brand strong {
  font-family: var(--font-display);
  font-size: 1.35rem;
  letter-spacing: 0.02em;
  font-weight: 700;
}
.brand span {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.top-actions { display: flex; gap: 0.5rem; flex-wrap: wrap; align-items: center; }

.btn, button.btn {
  appearance: none;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--text);
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.9rem;
  padding: 0.55rem 0.9rem;
  border-radius: 999px;
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s, transform 0.15s;
}
.btn:hover { border-color: var(--accent); }
.btn:active { transform: translateY(1px); }
.btn-primary {
  background: var(--signal);
  border-color: var(--signal);
  color: #041018;
}
.btn-primary:hover { filter: brightness(1.06); color: #041018; }
.btn-ghost { background: transparent; }
.btn-small { font-size: 0.8rem; padding: 0.4rem 0.75rem; }

.hero {
  display: grid;
  grid-template-columns: 1.3fr 1fr;
  gap: 1.5rem;
  align-items: stretch;
  margin-bottom: 2rem;
}
@media (max-width: 820px) {
  .hero { grid-template-columns: 1fr; }
}

.hero-copy h1 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3rem);
  line-height: 1.05;
  margin: 0 0 0.75rem;
  letter-spacing: -0.02em;
}
.hero-copy p {
  color: var(--muted);
  font-size: 1.05rem;
  max-width: 36rem;
  margin: 0 0 1.25rem;
}
.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}
.chip {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  border: 1px solid var(--line);
  background: var(--accent-dim);
  color: var(--text);
  padding: 0.35rem 0.6rem;
  border-radius: 999px;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.1rem 1.2rem;
  box-shadow: var(--shadow);
}

.path-rail {
  display: grid;
  gap: 0.65rem;
}
.path-step {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.75rem;
  align-items: start;
  padding: 0.55rem 0;
  border-bottom: 1px solid var(--line);
}
.path-step:last-child { border-bottom: 0; }
.path-num {
  font-family: var(--font-mono);
  color: var(--accent);
  font-size: 0.8rem;
  padding-top: 0.15rem;
}
.path-step strong { display: block; font-size: 0.95rem; }
.path-step span { color: var(--muted); font-size: 0.85rem; }

.section-title {
  font-family: var(--font-display);
  font-size: 1.35rem;
  margin: 0 0 0.85rem;
}

.module-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 0.85rem;
}

.module-card {
  text-align: left;
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1rem;
  cursor: pointer;
  color: inherit;
  font: inherit;
  transition: border-color 0.15s, transform 0.15s;
}
.module-card:hover { border-color: var(--accent); transform: translateY(-1px); }
.module-card.done { border-color: rgba(62, 207, 142, 0.45); }
.module-card .num {
  font-family: var(--font-mono);
  color: var(--accent);
  font-size: 0.75rem;
  letter-spacing: 0.06em;
}
.module-card h3 {
  font-family: var(--font-display);
  font-size: 1.05rem;
  margin: 0.35rem 0 0.4rem;
}
.module-card p { margin: 0; color: var(--muted); font-size: 0.88rem; }
.module-card .meta {
  margin-top: 0.75rem;
  display: flex;
  justify-content: space-between;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--faint);
}

.progress-bar {
  height: 6px;
  background: var(--line);
  border-radius: 999px;
  overflow: hidden;
  margin: 0.75rem 0 1.5rem;
}
.progress-bar > span {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--signal), var(--accent));
  width: 0%;
  transition: width 0.35s ease;
}

.lesson-layout {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 1.25rem;
}
@media (max-width: 800px) {
  .lesson-layout { grid-template-columns: 1fr; }
}

.side-nav a, .side-nav button {
  display: block;
  width: 100%;
  text-align: left;
  background: transparent;
  border: 0;
  color: var(--muted);
  padding: 0.45rem 0.5rem;
  border-radius: 8px;
  cursor: pointer;
  font: inherit;
}
.side-nav a:hover, .side-nav button:hover,
.side-nav .active { background: var(--accent-dim); color: var(--text); }
.side-nav .done::after {
  content: " ✓";
  color: var(--ok);
  font-family: var(--font-mono);
}

.lesson-panel h1 {
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 3vw, 2.1rem);
  margin: 0 0 0.5rem;
}
.lesson-panel .eyebrow {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.35rem;
}
.lesson-body p {
  font-size: 1.05rem;
  max-width: 42rem;
  margin: 0 0 1rem;
}
.visual-slot {
  margin: 1rem 0 1.25rem;
  border: 1px dashed var(--line);
  border-radius: var(--radius);
  background: var(--bg-elev);
  min-height: 160px;
  display: grid;
  place-items: center;
  overflow: hidden;
  position: relative;
}
.visual-slot img {
  width: 100%;
  height: auto;
  display: block;
  max-height: 360px;
  object-fit: cover;
}
.visual-slot .placeholder {
  color: var(--faint);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  text-align: center;
  padding: 1.5rem;
  letter-spacing: 0.04em;
}

.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 0.75rem;
  margin-top: 1.5rem;
  flex-wrap: wrap;
}

.quiz-card { margin-top: 0.5rem; }
.quiz-q {
  font-family: var(--font-display);
  font-size: 1.2rem;
  margin: 0 0 1rem;
}
.choice {
  display: block;
  width: 100%;
  text-align: left;
  margin: 0 0 0.55rem;
  padding: 0.85rem 1rem;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: var(--bg-elev);
  color: var(--text);
  font: inherit;
  cursor: pointer;
}
.choice:hover { border-color: var(--accent); }
.choice.correct { border-color: var(--ok); background: rgba(62, 207, 142, 0.1); }
.choice.wrong { border-color: var(--bad); background: rgba(232, 93, 93, 0.1); }
.feedback {
  margin-top: 1rem;
  padding: 0.9rem 1rem;
  border-left: 3px solid var(--accent);
  background: var(--accent-dim);
  border-radius: 0 var(--radius) var(--radius) 0;
}
.feedback strong { display: block; margin-bottom: 0.25rem; }

.setup-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}
@media (max-width: 700px) { .setup-grid { grid-template-columns: 1fr; } }
label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 0.35rem;
}
input, select {
  width: 100%;
  padding: 0.7rem 0.8rem;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--bg-elev);
  color: var(--text);
  font: inherit;
  margin-bottom: 0.85rem;
}
input:focus, select:focus, .btn:focus-visible, .choice:focus-visible, .module-card:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

.stat-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.75rem;
  margin: 1rem 0 1.5rem;
}
@media (max-width: 600px) { .stat-row { grid-template-columns: 1fr; } }
.stat {
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 0.85rem 1rem;
}
.stat b {
  display: block;
  font-family: var(--font-display);
  font-size: 1.4rem;
}
.stat span { color: var(--muted); font-size: 0.85rem; }

.hidden { display: none !important; }
.footer-note {
  margin-top: 2.5rem;
  padding-top: 1rem;
  border-top: 1px solid var(--line);
  color: var(--faint);
  font-size: 0.85rem;
}

.actions-row { display: flex; flex-wrap: wrap; gap: 0.5rem; margin: 1rem 0; }

.practice-log table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}
.practice-log th, .practice-log td {
  border-bottom: 1px solid var(--line);
  padding: 0.55rem 0.35rem;
  text-align: left;
}
.practice-log th {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--muted);
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
}