:root {
  --bg: #0d1117;
  --surface: #161b22;
  --border: #30363d;
  --text: #e6edf3;
  --muted: #8b949e;
  --accent: #58a6ff;
  --green: #3fb950;
  --red: #f85149;
  --yellow: #d29922;
  --purple: #bc8cff;
  --ring-bg: #1c2333;
  --code-bg: #0d1117;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  padding: 2rem;
  max-width: 960px;
  margin: 0 auto;
}

h1 {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 0.25rem;
  background: linear-gradient(135deg, var(--accent), var(--purple));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.subtitle {
  color: var(--muted);
  font-size: 0.95rem;
  margin-bottom: 2.5rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 1.5rem;
}

h2 {
  font-size: 1.35rem;
  margin: 2.5rem 0 1rem;
  color: var(--accent);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

h2 .num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.6rem;
  height: 1.6rem;
  border-radius: 50%;
  background: var(--accent);
  color: var(--bg);
  font-size: 0.8rem;
  font-weight: 700;
  flex-shrink: 0;
}

h3 {
  font-size: 1.05rem;
  margin: 1.5rem 0 0.5rem;
  color: var(--purple);
}

p, li { color: var(--text); margin-bottom: 0.6rem; }
ul { padding-left: 1.5rem; margin-bottom: 1rem; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* Input Section */
.input-section {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  margin: 1.5rem 0;
}

.input-row {
  display: flex;
  gap: 0.75rem;
  align-items: end;
  flex-wrap: wrap;
}

.input-group {
  flex: 1;
  min-width: 200px;
}

.input-group label {
  display: block;
  font-size: 0.85rem;
  color: var(--muted);
  margin-bottom: 0.35rem;
  font-weight: 600;
}

.input-group input {
  width: 100%;
  padding: 0.6rem 0.9rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace;
  font-size: 1.1rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  outline: none;
  transition: border-color 0.2s;
}

.input-group input:focus {
  border-color: var(--accent);
}

.input-group input::placeholder {
  color: var(--muted);
  opacity: 0.5;
  letter-spacing: 0.05em;
  text-transform: none;
}

.input-group select {
  width: 100%;
  padding: 0.6rem 0.9rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-size: 0.9rem;
  outline: none;
  cursor: pointer;
}

.input-group select:focus {
  border-color: var(--accent);
}

.btn {
  padding: 0.6rem 1.5rem;
  border: none;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.2s, transform 0.1s;
  white-space: nowrap;
}

.btn:active { transform: scale(0.97); }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

.btn-primary {
  background: var(--accent);
  color: var(--bg);
}

.btn-primary:hover:not(:disabled) { opacity: 0.9; }

/* Ring Visual */
.ring-visual {
  background: var(--ring-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 2rem;
  margin: 1.5rem 0;
  text-align: center;
}

.ring-svg { max-width: 340px; margin: 0 auto; display: block; }

/* Results */
.results { margin: 1.5rem 0; }

.solution-box {
  background: var(--surface);
  border: 1px solid var(--green);
  border-left: 4px solid var(--green);
  border-radius: 8px;
  padding: 1.25rem 1.5rem;
  margin: 1rem 0;
}

.solution-box.no-solution {
  border-color: var(--yellow);
  border-left-color: var(--yellow);
}

.solution-box .label {
  color: var(--green);
  font-weight: 600;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.4rem;
}

.solution-box.no-solution .label { color: var(--yellow); }

.solution-box .words {
  font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace;
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text);
}

.solution-box .words .sep {
  color: var(--muted);
  font-weight: 400;
  margin: 0 0.5rem;
}

.solution-box .meta {
  color: var(--muted);
  font-size: 0.82rem;
  margin-top: 0.4rem;
}

/* Tracking Table */
.tracking-section {
  margin: 1rem 0;
}

.tracking-section summary {
  cursor: pointer;
  color: var(--muted);
  font-size: 0.88rem;
  padding: 0.3rem 0;
  user-select: none;
}

.tracking-section summary:hover { color: var(--text); }

.tracking {
  width: 100%;
  border-collapse: collapse;
  margin: 0.5rem 0;
  font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace;
  font-size: 0.85rem;
}

.tracking th {
  text-align: left;
  padding: 0.5rem 0.75rem;
  border-bottom: 2px solid var(--border);
  color: var(--muted);
  font-weight: 600;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.tracking td {
  padding: 0.4rem 0.75rem;
  border-bottom: 1px solid var(--border);
}

.tracking .ok { color: var(--green); }
.tracking .blocked { color: var(--red); opacity: 0.6; }

/* Stats */
.stats {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  margin: 1rem 0;
}

.stat {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.6rem 1rem;
  font-size: 0.85rem;
}

.stat .value {
  font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace;
  color: var(--accent);
  font-weight: 700;
}

/* Loading */
.loading {
  display: none;
  align-items: center;
  gap: 0.5rem;
  color: var(--muted);
  font-size: 0.9rem;
  margin: 1rem 0;
}

.loading.active { display: flex; }

.spinner {
  width: 18px;
  height: 18px;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin { to { transform: rotate(360deg); } }

/* Error */
.error {
  background: rgba(248, 81, 73, 0.08);
  border: 1px solid rgba(248, 81, 73, 0.25);
  border-radius: 8px;
  padding: 0.8rem 1rem;
  color: var(--red);
  font-size: 0.9rem;
  margin: 1rem 0;
  display: none;
}

.error.active { display: block; }

/* About Section */
.about {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
}

.about p {
  font-size: 0.92rem;
  color: var(--muted);
}

/* Footer */
footer {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.8rem;
  line-height: 1.8;
}

footer a { color: var(--accent); }

/* Responsive */
@media (max-width: 640px) {
  body { padding: 1rem; }
  h1 { font-size: 1.5rem; }
  .input-row { flex-direction: column; }
  .solution-box .words { font-size: 1rem; }
  .ring-svg { max-width: 280px; }
  .stats { flex-direction: column; }
}