@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&family=Sora:wght@500;600;700&display=swap');

:root {
  --bg: #14161b;
  --surface: #1c1f25;
  --surface-2: #24272e;
  --surface-3: #2c3038;
  --border: #30333b;
  --border-strong: #3d414a;
  --text: #eceef0;
  --text-dim: #a3a7ae;
  --text-muted: #6c7078;
  --accent: #5fc9a8;
  --accent-dim: #3f8f74;
  --accent-glow: rgba(95, 201, 168, 0.15);
  --danger: #e07a68;
  --success: #6bc27f;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-heading: 'Sora', 'Inter', sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', Consolas, Menlo, monospace;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  background-image: radial-gradient(circle at 15% 0%, rgba(95, 201, 168, 0.06), transparent 40%);
  color: var(--text);
  font-family: var(--font-sans);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(20, 22, 27, 0.85);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  max-width: 980px;
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
}

header .brand {
  font-family: var(--font-heading);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.01em;
  display: flex;
  align-items: center;
  gap: 8px;
}

header .brand::before {
  content: '';
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 8px var(--accent-glow);
}

nav {
  display: flex;
  gap: 2px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 3px;
  flex-wrap: wrap;
}

nav a {
  color: var(--text-dim);
  text-decoration: none;
  font-size: 13px;
  font-weight: 500;
  padding: 7px 14px;
  border-radius: 7px;
  transition: color 0.15s, background 0.15s;
  white-space: nowrap;
}

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

nav a.active {
  background: var(--surface-3);
  color: var(--accent);
}

main {
  max-width: 720px;
  margin: 0 auto;
  padding: 48px 24px 100px;
}

h1 {
  font-family: var(--font-heading);
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.01em;
  margin: 0 0 10px;
}

h2 {
  font-family: var(--font-heading);
  font-size: 16px;
  font-weight: 600;
  margin: 32px 0 14px;
}

h3 {
  font-family: var(--font-heading);
  font-size: 13px;
  font-weight: 600;
  color: var(--text-dim);
  margin: 20px 0 10px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

p.subtitle {
  color: var(--text-dim);
  font-size: 15px;
  margin: 0 0 36px;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 24px 26px;
  margin-bottom: 22px;
}

label {
  display: block;
  font-size: 13px;
  color: var(--text-dim);
  margin-bottom: 7px;
  font-weight: 500;
}

textarea, input[type="text"], select {
  width: 100%;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 13px;
  padding: 10px 13px;
  margin-bottom: 18px;
  transition: border-color 0.15s;
}

textarea { min-height: 90px; resize: vertical; }

textarea:focus, input:focus, select:focus {
  outline: none;
  border-color: var(--accent-dim);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

button {
  background: var(--accent);
  color: #0d1210;
  border: none;
  border-radius: 8px;
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 600;
  padding: 10px 20px;
  cursor: pointer;
  transition: background 0.15s, transform 0.1s;
  margin-right: 8px;
  margin-bottom: 8px;
}

button:hover { background: #74d6b6; }
button:active { transform: scale(0.98); }

button.secondary {
  background: transparent;
  border: 1px solid var(--border-strong);
  color: var(--text-dim);
}

button.secondary:hover {
  border-color: var(--text-dim);
  color: var(--text);
  background: var(--surface-2);
}

.result {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-radius: 10px;
  padding: 15px 20px;
  margin: 18px 0;
  font-size: 14px;
  font-weight: 600;
  border: 1px solid transparent;
  flex-wrap: wrap;
  gap: 6px;
}

.result.accepted {
  background: rgba(107, 194, 127, 0.1);
  color: var(--success);
  border-color: rgba(107, 194, 127, 0.25);
}

.result.rejected {
  background: rgba(224, 122, 104, 0.1);
  color: var(--danger);
  border-color: rgba(224, 122, 104, 0.25);
}

.result.error {
  background: var(--surface-2);
  color: var(--text-dim);
  border-color: var(--border);
}

.trace, .chain {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 12px;
}

.trace .state, .chain .step {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 10px;
}

.trace .state.fail, .chain .step.dead { border-color: var(--danger); color: var(--danger); }
.trace .symbol, .chain .arrow { color: var(--text-muted); }

.hint {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: -10px;
  margin-bottom: 18px;
}

footer {
  text-align: center;
  color: var(--text-muted);
  font-size: 12px;
  padding: 32px 24px;
  border-top: 1px solid var(--border);
  margin-top: 40px;
}

.formal-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin: 18px 0;
}

.formal-card {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px;
}

.formal-card .label {
  font-size: 11px;
  color: var(--text-muted);
  margin-bottom: 5px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.formal-card .value {
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--accent);
  word-break: break-word;
}

table.transition-table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 18px;
  font-size: 13px;
  border-radius: 10px;
  overflow: hidden;
}

table.transition-table th, table.transition-table td {
  border: 1px solid var(--border);
  padding: 9px;
  text-align: center;
}

table.transition-table th {
  background: var(--surface-2);
  color: var(--text-dim);
  font-weight: 600;
  font-size: 12px;
}

table.transition-table td input {
  width: 100%;
  background: var(--surface-3);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 12px;
  padding: 6px 7px;
  text-align: center;
  margin: 0;
}

table.transition-table.readonly td {
  font-family: var(--font-mono);
  color: var(--text-dim);
}

.final-checks {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 18px;
}

.final-checks label {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--text);
  margin-bottom: 0;
  font-weight: 400;
}

.diagram-box {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
  overflow-x: auto;
}

.grammar-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 13px;
}

.grammar-list .rule {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 8px 12px;
}

.grammar-list .rule .nt { color: var(--accent); }

/* pohon penurunan, modul PDA/CFG */
.tree-view { font-family: var(--font-mono); font-size: 13px; }
.tree-node { margin: 4px 0; }
.tree-label {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 5px;
  padding: 3px 8px;
  color: var(--accent);
}
.tree-leaf { background: transparent; color: var(--text-dim); padding: 3px 8px; }
.tree-children {
  margin-left: 24px;
  padding-left: 12px;
  border-left: 1px solid var(--border);
  margin-top: 4px;
}

/* visualisasi stack PDA */
.stack-view {
  display: flex;
  flex-direction: column-reverse;
  gap: 4px;
  width: 80px;
  font-family: var(--font-mono);
  font-size: 13px;
}

.stack-view .cell {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 8px;
  text-align: center;
}

.stack-view .cell.bottom { border-color: var(--accent-dim); color: var(--accent); }

/* kontrol zoom untuk diagram dan pohon penurunan */
.zoom-controls {
  display: flex;
  gap: 8px;
  margin-bottom: 12px;
}

.zoom-btn {
  padding: 6px 12px;
  font-size: 12px;
  margin: 0;
}

.zoom-scroll {
  overflow: auto;
  max-height: 440px;
  border-radius: 8px;
  background: var(--surface-2);
  border: 1px solid var(--border);
}

.zoom-inner {
  transform-origin: 0 0;
  transition: transform 0.12s ease;
}

/* label kecil di atas judul halaman */
.eyebrow {
  display: inline-block;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--accent-glow);
  padding: 4px 10px;
  border-radius: 20px;
  margin-bottom: 12px;
}

/* panel teori/cara pakai yang bisa dibuka-tutup */
details.info-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  margin-bottom: 14px;
  overflow: hidden;
}

details.info-panel summary {
  cursor: pointer;
  list-style: none;
  padding: 14px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-weight: 600;
  font-size: 14px;
  color: var(--text);
}

details.info-panel summary::-webkit-details-marker { display: none; }

details.info-panel summary::after {
  content: '+';
  color: var(--text-muted);
  font-size: 18px;
  font-weight: 400;
}

details.info-panel[open] summary::after { content: '−'; }

details.info-panel summary:hover { color: var(--accent); }

details.info-panel .info-body {
  padding: 0 20px 18px;
  font-size: 13.5px;
  color: var(--text-dim);
  line-height: 1.75;
  border-top: 1px solid var(--border);
  padding-top: 14px;
}

details.info-panel .info-body p { margin: 0 0 10px; }
details.info-panel .info-body ol,
details.info-panel .info-body ul { margin: 0 0 10px; padding-left: 20px; }
details.info-panel .info-body li { margin-bottom: 6px; }
details.info-panel .info-body strong { color: var(--text); }

/* kotak catatan penting, versi lebih menonjol dari .hint biasa */
.note {
  background: var(--surface-2);
  border-left: 3px solid var(--accent-dim);
  border-radius: 6px;
  padding: 10px 14px;
  font-size: 12.5px;
  color: var(--text-dim);
  margin-bottom: 18px;
}

/* animasi halus saat hasil muncul */
@keyframes fadeSlideIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

.result { animation: fadeSlideIn 0.25s ease; }

/* rapikan tampilan di layar kecil */
@media (max-width: 600px) {
  .formal-grid { grid-template-columns: repeat(2, 1fr); }
  .header-inner { padding: 14px 16px; }
  nav a { padding: 6px 10px; font-size: 12px; }
  main { padding: 32px 16px 80px; }
  h1 { font-size: 23px; }
}