:root {
  --bg: #0a0a0b;
  --surface: #141416;
  --surface-2: #1c1c20;
  --border: #2a2a30;
  --text: #e4e4e7;
  --text-muted: #8b8b94;
  --accent: #6366f1;
  --accent-hover: #818cf8;
  --success: #22c55e;
  --error: #ef4444;
  --accent-dim: rgba(99, 102, 241, 0.1);
  --radius: 8px;
  --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
}

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

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-hover); }

/* Layout */
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }

header {
  border-bottom: 1px solid var(--border);
  padding: 16px 0;
}

header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 8px;
}

.logo span { color: var(--accent); }

nav { display: flex; gap: 24px; }
nav a { color: var(--text-muted); font-size: 0.9rem; }
nav a:hover { color: var(--text); }

/* Hero */
.hero {
  text-align: center;
  padding: 80px 0 60px;
}

.hero h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 16px;
  background: linear-gradient(135deg, var(--text) 0%, var(--accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p {
  color: var(--text-muted);
  font-size: 1.1rem;
  max-width: 600px;
  margin: 0 auto;
}

/* Tool Grid */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
  padding: 0 0 80px;
}

.tool-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  transition: border-color 0.2s, transform 0.2s;
  cursor: pointer;
  display: block;
  color: var(--text);
}

.tool-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.tool-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.tool-card p {
  color: var(--text-muted);
  font-size: 0.85rem;
}

.tool-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius);
  background: var(--surface-2);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 12px;
  font-size: 1.2rem;
}

/* Tool Page Layout */
.tool-page {
  padding: 40px 0 80px;
}

.tool-page h1 {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.tool-page .description {
  color: var(--text-muted);
  margin-bottom: 32px;
}

.tool-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.tool-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  display: flex;
  flex-direction: column;
}

.panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
}

.tool-textarea {
  width: 100%;
  min-height: 400px;
  padding: 16px;
  background: transparent;
  border: none;
  color: var(--text);
  font-family: var(--mono);
  font-size: 0.875rem;
  resize: vertical;
  outline: none;
  line-height: 1.6;
}

.tool-textarea::placeholder { color: var(--text-muted); opacity: 0.5; }

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--surface-2);
  color: var(--text);
  font-size: 0.8rem;
  cursor: pointer;
  transition: all 0.15s;
  font-family: var(--font);
}

.btn:hover { border-color: var(--accent); color: var(--accent); }

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

.btn-primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); color: white; }

.btn-group { display: flex; gap: 8px; flex-wrap: wrap; }

/* Action Bar */
.action-bar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px 0;
}

/* Options Row */
.options-row {
  display: flex;
  gap: 16px;
  align-items: center;
  padding: 12px 0;
  flex-wrap: wrap;
}

.options-row label {
  font-size: 0.85rem;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 6px;
}

.options-row select, .options-row input[type="number"] {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 4px 8px;
  border-radius: 4px;
  font-size: 0.85rem;
  font-family: var(--font);
}

/* Status Messages */
.status {
  font-size: 0.8rem;
  padding: 8px 12px;
  border-radius: 4px;
  margin-top: 8px;
}

.status-success { background: rgba(34, 197, 94, 0.1); color: var(--success); }
.status-error { background: rgba(239, 68, 68, 0.1); color: var(--error); }

/* Footer */
footer {
  border-top: 1px solid var(--border);
  padding: 24px 0;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.8rem;
}

/* Responsive */
@media (max-width: 768px) {
  .tool-layout { grid-template-columns: 1fr; }
  .calc-layout { grid-template-columns: 1fr; }
  .form-row { grid-template-columns: 1fr; }
  .result-grid { grid-template-columns: 1fr; }
  .hero h1 { font-size: 1.75rem; }
  .hero { padding: 40px 0 30px; }
  .tools-grid { grid-template-columns: 1fr; }
  header .container { flex-direction: column; gap: 12px; }
  .data-table { font-size: 0.75rem; }
  .data-table th, .data-table td { padding: 8px 6px; }
  .result-value { font-size: 1.5rem; }
}

@media (max-width: 480px) {
  .calc-page { padding: 24px 0 60px; }
  .panel-body { padding: 16px; }
}

/* Hash output grid */
.hash-results {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 16px;
}

.hash-row {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.hash-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.hash-value {
  font-family: var(--mono);
  font-size: 0.8rem;
  word-break: break-all;
  color: var(--text);
  background: var(--surface-2);
  padding: 8px 12px;
  border-radius: 4px;
  cursor: pointer;
  transition: background 0.15s;
}

.hash-value:hover { background: var(--border); }

/* Color converter */
.color-preview {
  width: 100%;
  height: 120px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  margin-bottom: 16px;
  transition: background 0.2s;
}

.color-inputs {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  padding: 16px;
}

.color-field label {
  display: block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 4px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.color-field input {
  width: 100%;
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 8px 12px;
  border-radius: 4px;
  font-family: var(--mono);
  font-size: 0.85rem;
  outline: none;
}

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

/* Timestamp */
.ts-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  padding: 16px;
}

.ts-field { display: flex; flex-direction: column; gap: 4px; }
.ts-field label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
}

.ts-field input, .ts-field select {
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 8px 12px;
  border-radius: 4px;
  font-family: var(--mono);
  font-size: 0.85rem;
  outline: none;
}

.ts-current {
  grid-column: 1 / -1;
  text-align: center;
  padding: 16px;
  background: var(--surface-2);
  border-radius: var(--radius);
  font-family: var(--mono);
  font-size: 1.5rem;
  color: var(--accent);
}

/* Back link */
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  color: var(--text-muted);
  font-size: 0.85rem;
  margin-bottom: 16px;
}

.back-link:hover { color: var(--text); }

/* Calculator Page Layout */
.calc-page {
  padding: 40px 0 80px;
}

.calc-page h1 {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.calc-page .description {
  color: var(--text-muted);
  margin-bottom: 32px;
}

/* Calculator Panels */
.calc-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-bottom: 32px;
}

.calc-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.calc-panel-full {
  grid-column: 1 / -1;
}

.panel-body {
  padding: 20px;
}

/* Form Elements */
.form-group {
  margin-bottom: 16px;
}

.form-group label {
  display: block;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 6px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.form-group input,
.form-group select {
  width: 100%;
  padding: 10px 14px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-size: 0.9rem;
  font-family: var(--font);
  outline: none;
  transition: border-color 0.2s;
}

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

.form-group input::placeholder {
  color: var(--text-muted);
  opacity: 0.5;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

/* Result Display */
.result-value {
  font-family: var(--mono);
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 4px;
}

.result-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.result-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.result-item {
  padding: 16px;
  background: var(--surface-2);
  border-radius: 6px;
}

.result-item .value {
  font-family: var(--mono);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--accent);
}

.result-item .label {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 4px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Info/Education Section */
.info-section {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-top: 32px;
}

.info-section h2 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 12px;
  color: var(--text);
}

.info-section p {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 12px;
  line-height: 1.7;
}

.info-section ul {
  color: var(--text-muted);
  font-size: 0.9rem;
  padding-left: 20px;
  margin-bottom: 12px;
}

.info-section li {
  margin-bottom: 6px;
}

/* Data Table */
.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
}

.data-table th {
  text-align: left;
  padding: 10px 12px;
  background: var(--surface-2);
  color: var(--text-muted);
  font-weight: 600;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border-bottom: 1px solid var(--border);
}

.data-table td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
  color: var(--text);
  font-family: var(--mono);
  font-size: 0.8rem;
}

.data-table tbody tr:hover {
  background: var(--surface-2);
}

/* Chart canvas */
.chart-container {
  padding: 20px;
  height: 300px;
  position: relative;
}

/* Scale / Meter */
.scale-bar {
  height: 24px;
  border-radius: 12px;
  background: linear-gradient(to right, #22c55e, #84cc16, #f59e0b, #ef4444, #dc2626);
  position: relative;
  margin: 16px 0;
}

.scale-marker {
  position: absolute;
  top: -8px;
  width: 4px;
  height: 40px;
  background: white;
  border-radius: 2px;
  transform: translateX(-50%);
  transition: left 0.3s ease;
}