:root {
  --bg-color: #0d1117;
  --panel-bg: #161b22;
  --card-bg: #1c2128;
  --border-color: #30363d;
  --text-primary: #c9d1d9;
  --text-secondary: #8b949e;
  --accent-color: #58a6ff;
  --error-color: #f85149;
  
  --network-bit-bg: rgba(88, 166, 255, 0.2);
  --network-bit-text: #58a6ff;
  --host-bit-bg: rgba(63, 185, 80, 0.2);
  --host-bit-text: #3fb950;

  --font-sans: 'Inter', -apple-system, sans-serif;
  --font-mono: 'Fira Code', ui-monospace, SFMono-Regular, monospace;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-color);
  color: var(--text-primary);
  min-height: 100vh;
}

.code-font { font-family: var(--font-mono); }
.mt-2 { margin-top: 1rem; }
.mt-4 { margin-top: 2rem; }
.flex-grow { flex-grow: 1; }
.highlight { color: var(--accent-color); font-weight: 600; }

header {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  border-bottom: 1px solid var(--border-color);
  padding: 1.5rem 2rem;
}

.header-left h1 { font-size: 1.5rem; font-weight: 600; margin-top: 0.5rem; }
.header-right p { color: var(--text-secondary); font-size: 0.875rem; }

.back-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  transition: color 0.2s;
  display: inline-block;
  margin-bottom: 0.5rem;
}
.back-link:hover { color: var(--accent-color); }

.main-content {
  padding: 2rem;
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1.5rem;
}
.card h2 { font-size: 1.25rem; margin-bottom: 1.5rem; color: #fff; }

button {
  cursor: pointer;
  font-family: inherit;
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: 6px;
  padding: 0.65rem 1.5rem;
  height: 40px;
  transition: 0.2s;
}

.primary-btn { background-color: #238636; color: #fff; border: 1px solid rgba(240, 246, 252, 0.1); }
.primary-btn:hover { background-color: #2ea043; }

/* Input */
.input-container {
  display: flex;
  gap: 1.5rem;
  align-items: flex-end;
  flex-wrap: wrap;
}

.input-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.input-group label {
  font-size: 0.875rem;
  color: var(--text-secondary);
  font-weight: 500;
  text-transform: uppercase;
}

.text-input {
  background-color: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--text-primary);
  padding: 0 1rem;
  height: 40px;
  outline: none;
  font-size: 1rem;
}
.text-input:focus { border-color: var(--accent-color); }

.ip-group { flex-grow: 1; max-width: 300px; }
.cidr-group { width: 100px; }

.cidr-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}
.cidr-wrapper .prefix {
  position: absolute;
  left: 10px;
  color: var(--text-secondary);
  font-family: var(--font-mono);
}
.cidr-wrapper input {
  width: 100%;
  padding-left: 20px;
}

.error-text {
  color: var(--error-color);
  font-size: 0.875rem;
  margin-top: 1rem;
  min-height: 1.2em;
}

/* Layout */
.results-layout {
  display: grid;
  grid-template-columns: 400px 1fr;
  gap: 1.5rem;
}

@media (max-width: 900px) {
  .results-layout { grid-template-columns: 1fr; }
}

/* Details Table */
.details-table {
  width: 100%;
  border-collapse: collapse;
}

.details-table td {
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--border-color);
  font-size: 0.95rem;
}
.details-table tr:last-child td { border-bottom: none; }
.details-table td:first-child { color: var(--text-secondary); }
.details-table td:last-child { text-align: right; }

/* Binary Visualizer */
.binary-row {
  margin-bottom: 2rem;
}
.bin-label {
  display: block;
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
  text-transform: uppercase;
}

.bin-blocks {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.bin-octet {
  display: flex;
  gap: 2px;
  background: var(--panel-bg);
  padding: 0.5rem;
  border-radius: 6px;
  border: 1px solid var(--border-color);
}

.bit {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 28px;
  border-radius: 3px;
  font-size: 0.875rem;
}

.bit.net { background-color: var(--network-bit-bg); color: var(--network-bit-text); }
.bit.host { background-color: var(--host-bit-bg); color: var(--host-bit-text); }

.legend { display: flex; gap: 1.5rem; align-items: center; font-size: 0.875rem; }
.legend-item { display: flex; align-items: center; gap: 0.5rem; }
.dot { width: 12px; height: 12px; border-radius: 50%; }
.network-dot { background-color: var(--network-bit-text); }
.host-dot { background-color: var(--host-bit-text); }

.info-box {
  background-color: var(--panel-bg);
  border-left: 4px solid var(--accent-color);
  padding: 1rem;
  border-radius: 0 6px 6px 0;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}
.info-box code { color: var(--text-primary); }