@import url('https://fonts.googleapis.com/css2?family=Jua&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Zain:ital,wght@0,200;0,300;0,400;0,700;0,800;0,900;1,300;1,400&display=swap');
:root {
  /* Backgrounds — dark navy blues */
  --bg:          #0a0d14;
  --bg2:         #0f1520;
  --bg3:         #16202e;
  --bg4:         #1c2a3a;

  /* Borders */
  --border:      #1e2d42;
  --border2:     #253648;
  --border3:     #2e4260;

  /* Text */
  --text:        #d8e4f0;
  --text-muted:  #6a8299;
  --text-dim:    #3d5470;

  /* Accents — silver */
  --accent:      #a8c0d8;      /* silver-blue — main accent */
  --accent-glow: rgba(168,192,216,0.18);
  --accent-alt:  #7b9fc4;      /* mid steel blue */
  --accent3:     #e0c97a;      /* gold for start arrow */
  --accent-soft: rgba(168,192,216,0.08);

  /* Danger / Success */
  --danger:      #e87070;
  --success:     #5ecfaa;

  /* Graph node colours */
  --node-fill:   #111c2c;
  --node-stroke: #a8c0d8;
  --node-accept: #7b9fc4;

  /* Fonts */
  --font-mono:   'Jet Brains Mono', monospace;
  --font-ui:     'Zain', sans-serif;

  /* Misc */
  --radius:      8px;
  --radius-lg:   14px;
  --shadow:      0 4px 28px rgba(0,0,0,0.6);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 15px; }

body {
  font-family: var(--font-ui);
  background: #0a0d14;
    background-image: radial-gradient(circle, rgba(255, 255, 255, 0.2) 1.5px, transparent 1.5px);
    background-size: 30px 30px;
    background-position: 0 0;
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
  overflow-x: hidden;
}


   /* HEADER */

.site-header {
  background: var(--bg2);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(8px);
}
.header-inner {
  max-width: 1600px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  gap: 32px;
  height: 64px;
}
.logo {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}
.logo-icon {
  font-family: var(--font-mono);
  font-size: 1.3rem;
  color: var(--accent);
  background: var(--accent-soft);
  border: 1px solid rgba(168,192,216,0.2);
  width: 42px; height: 42px;
  display: flex; align-items: center; justify-content: center;
  border-radius: var(--radius);
}
.logo-title {
  font-size: 1.1rem;
  font-weight: 800;
  letter-spacing: 0.05em;
  color: var(--accent);
}
.logo-sub {
  font-size: 0.7rem;
  color: var(--text-muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

/*TAB NAV*/
.tab-nav {
  display: flex;
  gap: 4px;
  margin-left: auto;
}
.tab-btn {
  background: none;
  border: 1px solid transparent;
  color: var(--text-muted);
  font-family: var(--font-ui);
  font-size: 0.88rem;
  font-weight: 600;
  padding: 7px 18px;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all 0.18s;
  letter-spacing: 0.02em;
}
.tab-btn:hover {
  color: var(--text);
  background: var(--bg3);
  border-color: var(--border2);
}
.tab-btn.active {
  color: var(--accent);
  background: var(--accent-soft);
  border-color: rgba(168,192,216,0.25);
}

/*LAYOUT*/
.app-main {
  max-width: 1600px;
  margin: 0 auto;
  padding: 24px;
}
.tab-panel { display: none; }
.tab-panel.active { display: block; }

.panel-layout {
  display: grid;
  grid-template-columns: 410px 1fr;
  gap: 20px;
  align-items: start;
}
@media (max-width: 900px) {
  .panel-layout { grid-template-columns: 1fr; }
}
.panel-left { display: flex; flex-direction: column; gap: 16px; }

/* CARD*/
.card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow);
}
.card-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 18px;
  border-bottom: 1px solid var(--border);
  background: linear-gradient(to right, rgba(168,192,216,0.04), transparent);
}
.card-icon {
  font-size: 1.1rem;
  color: var(--accent);
  width: 26px;
  text-align: center;
}
.card-header h2 {
  font-size: 0.93rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--text);
}
.card-body { padding: 18px; }

/* SYMBOL INSERT BAR*/
.sym-bar {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 8px;
  flex-wrap: wrap;
}
.sym-bar-label {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-dim);
  margin-right: 2px;
}
.sym-btn {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  font-weight: 600;
  padding: 4px 12px;
  background: var(--bg3);
  border: 1px solid var(--border3);
  color: var(--accent);
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.15s;
  line-height: 1.4;
  user-select: none;
}
.sym-btn:hover {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
  box-shadow: 0 0 10px var(--accent-glow);
  transform: translateY(-1px);
}
.sym-btn:active { transform: translateY(0); }

/* GRAPH CARD*/
.graph-card {
  position: sticky;
  top: 80px;
}
.graph-viewport {
  position: relative;
  width: 100%;
  height: calc(100vh - 200px);
  min-height: 500px;
  background: var(--bg);
  background-image: radial-gradient(circle, var(--border) 1px, transparent 1px);
  background-size: 28px 28px;
  overflow: hidden;
  cursor: grab;
}
.graph-viewport:active { cursor: grabbing; }
#pda-svg, #p2c-svg {
  width: 100%; height: 100%;
  display: block;
  position: absolute;
  top: 0; left: 0;
}

/*GRAPH CONTROLS — bottom-right d-pad overlay*/
.graph-controls-overlay {
  position: absolute;
  bottom: 18px;
  right: 18px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  z-index: 10;
  user-select: none;
}

/* D-pad cluster */
.gc-dpad {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 3px;
  background: rgba(10,13,20,0.75);
  border: 1px solid var(--border3);
  border-radius: 12px;
  padding: 8px;
  backdrop-filter: blur(6px);
}
.gc-row {
  display: flex;
  gap: 3px;
  align-items: center;
  justify-content: center;
}

/* Zoom +/- strip below d-pad */
.gc-zoom {
  display: flex;
  gap: 4px;
  background: rgba(10,13,20,0.75);
  border: 1px solid var(--border3);
  border-radius: 8px;
  padding: 5px 8px;
  backdrop-filter: blur(6px);
}

.ctrl-btn {
  width: 32px; height: 32px;
  background: var(--bg3);
  border: 1px solid var(--border2);
  color: var(--text-muted);
  border-radius: 7px;
  cursor: pointer;
  font-size: 0.95rem;
  font-family: var(--font-mono);
  display: flex; align-items: center; justify-content: center;
  transition: all 0.14s;
  flex-shrink: 0;
  line-height: 1;
}
.ctrl-btn:hover {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
  box-shadow: 0 0 10px var(--accent-glow);
  color: #0a0d14;
}
.ctrl-btn:active { transform: scale(0.9); }
.ctrl-fit {
  background: var(--bg4);
  color: var(--accent);
  border-color: var(--border3);
}

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   GRAPH EMPTY STATE
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
.graph-empty {
  position: absolute; inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center; justify-content: center;
  gap: 12px;
  color: var(--text-muted);
  font-size: 0.9rem;
  pointer-events: none;
}
.empty-icon {
  font-size: 3rem;
  color: var(--border2);
  font-family: var(--font-mono);
}
.graph-empty.hidden { display: none; }

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   FORM ELEMENTS
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
.field-label {
  display: block;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 7px;
}
.field-label .hint {
  font-weight: 400;
  text-transform: none;
  letter-spacing: 0;
  font-size: 0.73rem;
  color: var(--text-dim);
}
.mt { margin-top: 14px; }

.code-textarea, .code-input {
  width: 100%;
  background: var(--bg);
  border: 1px solid var(--border2);
  border-radius: var(--radius);
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 0.84rem;
  padding: 10px 12px;
  resize: vertical;
  line-height: 1.65;
  transition: border-color 0.18s, box-shadow 0.18s;
  outline: none;
}
.code-textarea:focus, .code-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(168,192,216,0.1);
}
.code-input { resize: none; height: 40px; padding: 9px 12px; }

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   ACTION BUTTONS
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
.btn-row {
  display: flex;
  gap: 10px;
  margin-top: 16px;
}
.btn {
  font-family: var(--font-ui);
  font-size: 0.88rem;
  font-weight: 700;
  padding: 10px 22px;
  border-radius: var(--radius);
  border: none;
  cursor: pointer;
  transition: all 0.18s;
  letter-spacing: 0.03em;
}
.btn-primary {
  background: var(--accent);
  color: #0a0d14;
  box-shadow: 0 0 18px rgba(168,192,216,0.2);
}
.btn-primary:hover {
  background: #c0d4e8;
  box-shadow: 0 0 28px rgba(168,192,216,0.38);
  transform: translateY(-1px);
}
.btn-primary:active { transform: translateY(0); }
.btn-ghost {
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border2);
}
.btn-ghost:hover {
  color: var(--text);
  border-color: var(--accent-alt);
  background: var(--bg3);
}

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   ERROR BOX
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
.error-box {
  margin-top: 12px;
  padding: 10px 14px;
  background: rgba(232,112,112,0.07);
  border: 1px solid rgba(232,112,112,0.28);
  border-radius: var(--radius);
  color: var(--danger);
  font-size: 0.82rem;
  font-family: var(--font-mono);
}
.error-box.hidden { display: none; }

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   CONVERSION STEPS
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
.steps-list { display: flex; flex-direction: column; gap: 9px; }
.step-item {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 10px 14px;
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  border-left: 3px solid var(--accent);
  font-size: 0.83rem;
  line-height: 1.55;
  animation: fadeInUp 0.25s ease forwards;
}
.step-num {
  flex-shrink: 0;
  width: 22px; height: 22px;
  background: var(--accent);
  color: #0a0d14;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.7rem;
  font-weight: 700;
}
.step-item code {
  font-family: var(--font-mono);
  font-size: 0.79rem;
  background: rgba(168,192,216,0.07);
  padding: 1px 5px;
  border-radius: 4px;
  color: var(--accent);
}

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   TRANSITION TABLE
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
.table-scroll { overflow-x: auto; }
.trans-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.8rem;
  font-family: var(--font-mono);
}
.trans-table th {
  padding: 8px 12px;
  text-align: left;
  color: var(--text-muted);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  border-bottom: 1px solid var(--border2);
  font-family: var(--font-ui);
  font-weight: 700;
  white-space: nowrap;
}
.trans-table td {
  padding: 7px 12px;
  border-bottom: 1px solid var(--border);
  color: var(--text);
  white-space: nowrap;
}
.trans-table tr:last-child td { border-bottom: none; }
.trans-table tr:hover td { background: var(--bg3); }
.trans-table td:first-child { color: var(--accent); }
.trans-table td:nth-child(6) { color: var(--text-muted); font-size: 0.74rem; }

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   CFG OUTPUT
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
.cfg-output-box {
  background: var(--bg);
  border: 1px solid var(--border2);
  border-radius: var(--radius);
  padding: 14px;
  font-family: var(--font-mono);
  font-size: 0.83rem;
  line-height: 2;
  max-height: 320px;
  overflow-y: auto;
}
.cfg-rule {
  display: flex;
  gap: 8px;
  align-items: baseline;
  padding: 1px 0;
}
.cfg-lhs { color: var(--accent-alt); font-weight: 600; min-width: 90px; }
.cfg-arrow { color: var(--text-muted); }
.cfg-rhs { color: var(--text); }

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   EXAMPLES GRID
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
.examples-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 18px;
  padding: 4px;
}
.example-card {
  display: flex;
  flex-direction: column;
  gap: 11px;
  padding: 22px;
  transition: transform 0.18s, box-shadow 0.18s;
}
.example-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 10px 36px rgba(0,0,0,0.55);
}
.ex-badge {
  display: inline-block;
  padding: 3px 11px;
  border-radius: 20px;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: rgba(168,192,216,0.09);
  color: var(--accent);
  border: 1px solid rgba(168,192,216,0.22);
  width: fit-content;
}
.ex-badge.p2c {
  background: rgba(123,159,196,0.09);
  color: var(--accent-alt);
  border-color: rgba(123,159,196,0.22);
}
.example-card h3 { font-size: 1.05rem; font-weight: 700; }
.example-card p  { font-size: 0.83rem; color: var(--text-muted); flex: 1; }
.example-card code {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.79rem;
  background: var(--bg);
  border: 1px solid var(--border2);
  border-radius: var(--radius);
  padding: 9px 12px;
  color: var(--accent);
  line-height: 1.75;
}

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   SVG GRAPH ELEMENTS
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
.state-circle {
  fill: var(--node-fill);
  stroke: var(--accent);
  stroke-width: 2;
  filter: drop-shadow(0 0 7px rgba(168,192,216,0.22));
  transition: fill 0.2s;
  cursor: pointer;
}
.state-circle:hover { fill: rgba(168,192,216,0.1); }
.state-circle.accept {
  stroke: var(--node-accept);
  filter: drop-shadow(0 0 8px rgba(123,159,196,0.35));
}
.state-circle.start-state {
  stroke: var(--accent3);
  filter: drop-shadow(0 0 8px rgba(224,201,122,0.35));
}
.state-label {
  font-family: var(--font-mono);
  font-size: 13px;
  fill: var(--text);
  pointer-events: none;
  font-weight: 600;
}
.edge-path {
  fill: none;
  stroke: var(--accent);
  stroke-width: 1.8;
  marker-end: url(#arrow);
}
.edge-path.self { stroke: var(--accent-alt); }
.edge-label-text {
  font-family: var(--font-mono);
  font-size: 11px;
  fill: var(--text);
  pointer-events: none;
}

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   ANIMATION
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── LANDING PAGE ── */
.landing-hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - 64px);
  text-align: center;
  gap: 10px;
  padding: 40px 24px;
}
.landing-title {
  font-family: 'Jua', sans-serif;
  font-size: 6rem;
  font-weight: 400;
  color: var(--accent);
  letter-spacing: 0.04em;
  line-height: 1.1;
}
.landing-sub {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-muted);
  margin-bottom: 16px;
}
.landing-card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 36px 40px;
  width: 100%;
  max-width: 520px;
  box-shadow: var(--shadow);
  text-align: left;
}

/* ── RESULTS PAGE ── */
.results-layout {
  display: grid;
  grid-template-columns: 420px 1fr;
  gap: 20px;
  align-items: start;
}
@media (max-width: 900px) {
  .results-layout { grid-template-columns: 1fr; }
}
.results-left { display: flex; flex-direction: column; gap: 16px; }

/* ── PAGE TRANSITIONS ── */
.page { display: none; }
.page.active { display: block; }

.back-btn-row {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 20px;
}
.btn-back {
  background: var(--bg3);
  border: 1px solid var(--border2);
  color: var(--text-muted);
  font-family: var(--font-ui);
  font-size: 0.85rem;
  font-weight: 700;
  padding: 8px 16px;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all 0.15s;
  display: flex;
  align-items: center;
  gap: 6px;
}
.btn-back:hover {
  color: var(--text);
  border-color: var(--accent);
  background: var(--bg4);
}
.results-heading {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-muted);
  letter-spacing: 0.03em;
}

/* ── CFG FORMAL TUPLE ── */
.cfg-tuple {
  margin-bottom: 14px;
  padding: 12px 14px;
  background: var(--bg3);
  border: 1px solid var(--border2);
  border-radius: var(--radius);
}
.tuple-title {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 10px;
  letter-spacing: 0.05em;
}
.tuple-row {
  display: flex;
  gap: 10px;
  font-size: 0.8rem;
  font-family: var(--font-mono);
  padding: 3px 0;
  border-bottom: 1px solid var(--border);
}
.tuple-row:last-child { border-bottom: none; }
.tuple-label {
  color: var(--text-muted);
  min-width: 130px;
  flex-shrink: 0;
}
.tuple-val { color: var(--text); }

.cfg-divider {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-dim);
  padding: 8px 0 6px 0;
  border-bottom: 1px solid var(--border2);
  margin-bottom: 8px;
}


/* ─────────────────────────────────────────────
   EDGE LABEL — always visible, hover highlight
   ───────────────────────────────────────────── */

/* Default label appearance */
.edge-label-group {
  pointer-events: all;
  transition: filter 0.15s ease;
}

/* Label box stroke in normal state */
.edge-label-group .label-bg {
  stroke: var(--accent);
  stroke-width: 1.2;
  transition: stroke 0.15s ease, stroke-width 0.15s ease;
}

/* Label text colour in normal state */
.edge-label-group .label-text {
  fill: var(--accent);
  transition: fill 0.15s ease;
}

/* ── HOVERED state ── */
.edge-label-group.label-hovered .label-bg {
  stroke: #ffffff;
  stroke-width: 2;
  fill: #1a2540;
}

.edge-label-group.label-hovered .label-text {
  fill: #ffffff;
}

.edge-label-group.label-hovered {
  filter: drop-shadow(0 0 6px rgba(255, 255, 255, 0.35));
}