:root {
  --bg: #020617;
  --bg-soft: #0b1220;
  --surface: #020617;
  --accent: #3b82f6;
  --accent-soft: rgba(59, 130, 246, 0.16);
  --text: #e5e7eb;
  --text-muted: #9ca3af;
  --danger: #f97373;
  --radius-lg: 12px;
  --radius-sm: 6px;
  --shadow-soft: 0 18px 42px rgba(15, 23, 42, 0.75);
  --border-subtle-color: rgba(148, 163, 184, 0.32);
  --border-subtle: 1px solid var(--border-subtle-color);
  --transition-fast: 0.18s ease-out;
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

/* Reset / Base */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  min-height: 100%;
}

body {
  font-family: var(--font-sans);
  background: radial-gradient(circle at top, #1e293b 0, #020617 45%, #000 100%);
  color: var(--text);
  line-height: 1.5;
}

/* Layout */
.container {
  width: 100%;
  max-width: 960px;
  margin: 0 auto;
  padding: 1.5rem;
}

/* Header */
.site-header {
  border-bottom: var(--border-subtle);
  background: linear-gradient(135deg, rgba(15, 23, 42, 0.98), rgba(15, 23, 42, 0.9));
  backdrop-filter: blur(18px);
  position: sticky;
  top: 0;
  z-index: 20;
}

.site-header-inner {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.75rem;
  padding-block: 0.9rem;
}

.site-header h1 {
  margin: 0;
  font-size: 1.6rem;
  letter-spacing: 0.03em;
}

.tagline {
  margin: 0.15rem 0 0;
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* Main */
.main-content {
  padding-top: 1.5rem;
}

/* Footer */
.site-footer {
  margin-top: 2rem;
  padding: 1.25rem 0 2rem;
  border-top: var(--border-subtle);
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* Tabs */
.tools-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin: 1.2rem 0 1.25rem;
  padding: 0.25rem;
  background: rgba(15, 23, 42, 0.9);
  border-radius: 999px;
  border: var(--border-subtle);
  box-shadow: var(--shadow-soft);
}

.tool-tab {
  border: none;
  background: transparent;
  color: var(--text-muted);
  padding: 0.4rem 0.95rem;
  border-radius: 999px;
  cursor: pointer;
  font-size: 0.85rem;
  white-space: nowrap;
  transition: background var(--transition-fast),
    color var(--transition-fast),
    transform var(--transition-fast),
    box-shadow var(--transition-fast);
}

.tool-tab:hover {
  color: var(--text);
}

.tool-tab.active {
  background: var(--accent-soft);
  color: var(--accent);
  transform: translateY(-1px);
  box-shadow: 0 10px 24px rgba(37, 99, 235, 0.4);
}

/* Tool Panels */
.tool-panel {
  display: none;
  background: radial-gradient(circle at top left, #111827, var(--bg));
  padding: 1.5rem;
  border-radius: var(--radius-lg);
  border: var(--border-subtle);
  box-shadow: var(--shadow-soft);
}

.tool-panel.active {
  display: block;
}

.tool-panel + .tool-panel {
  margin-top: 1.25rem;
}

.tool-panel h2 {
  margin-top: 0;
  margin-bottom: 0.35rem;
  font-size: 1.05rem;
}

.tool-panel p {
  margin-top: 0;
  margin-bottom: 0.9rem;
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* Buttons */
.primary-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  background: linear-gradient(135deg, #2563eb, #4f46e5);
  color: #f9fafb;
  font-weight: 500;
  border-radius: 999px;
  border: none;
  padding: 0.5rem 1.3rem;
  font-size: 0.9rem;
  cursor: pointer;
  box-shadow: 0 12px 24px rgba(37, 99, 235, 0.35);
  transition: transform var(--transition-fast),
    box-shadow var(--transition-fast),
    filter var(--transition-fast),
    opacity var(--transition-fast);
}

.primary-btn:hover {
  transform: translateY(-1px);
  filter: brightness(1.05);
  box-shadow: 0 14px 32px rgba(37, 99, 235, 0.45);
}

.primary-btn:active {
  transform: translateY(0);
  box-shadow: 0 8px 18px rgba(37, 99, 235, 0.3);
}

.primary-btn:disabled {
  opacity: 0.6;
  cursor: default;
  box-shadow: none;
}

/* Forms */
.lookup-form {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  margin-bottom: 1rem;
}

.lookup-form input[type="text"],
.lookup-form input[type="number"],
.lookup-form select {
  flex: 1 1 200px;
  min-width: 0;
  padding: 0.5rem 0.75rem;
  border-radius: 999px;
  border: var(--border-subtle);
  background: rgba(15, 23, 42, 0.95);
  color: var(--text);
  outline: none;
  font-size: 0.9rem;
  transition: border-color var(--transition-fast),
    box-shadow var(--transition-fast),
    background var(--transition-fast);
}

.lookup-form input::placeholder {
  color: var(--text-muted);
}

.lookup-form input:focus,
.lookup-form select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px rgba(59, 130, 246, 0.7);
}

/* Result cards / grids */
.result-card,
#my-ip-result,
#ipv4-result,
#ipv6-result,
#dec-hex-result,
#validator-result,
#cidr-result {
  margin-top: 0.75rem;
  padding: 1rem 1.1rem;
  background: rgba(15, 23, 42, 0.96);
  border-radius: var(--radius-lg);
  border: var(--border-subtle);
}

.result-card h3 {
  margin-top: 0;
  margin-bottom: 0.75rem;
  font-size: 1rem;
}

.result-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 0.75rem 1.5rem;
}

.result-grid .label {
  display: block;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.result-grid .value {
  display: block;
  font-size: 0.95rem;
  margin-top: 0.15rem;
}

/* Error messages */
.error-msg {
  margin-top: 0.75rem;
  color: var(--danger);
  font-size: 0.85rem;
}

.hidden {
  display: none !important;
}

/* Responsive */
@media (max-width: 640px) {
  .container {
    padding-inline: 1rem;
  }

  .site-header-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .site-header h1 {
    font-size: 1.3rem;
  }

  .tools-nav {
    justify-content: flex-start;
  }

  .tool-panel {
    padding: 1.1rem;
  }
}