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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: #0a0a0f;
  color: #e0e0e0;
  line-height: 1.7;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 40px 20px;
}

header {
  text-align: center;
  padding: 60px 0 40px;
}

h1 {
  font-size: 1.8em;
  font-weight: 700;
  color: #ffffff;
  line-height: 1.3;
  margin-bottom: 16px;
}

.subtitle {
  font-size: 1.05em;
  color: #888;
  margin-bottom: 24px;
}

.links {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 10px 24px;
  border-radius: 8px;
  background: #1a1a2e;
  color: #e0e0e0;
  text-decoration: none;
  font-weight: 500;
  font-size: 0.9em;
  transition: all 0.2s;
  border: 1px solid #333;
}

.btn:hover {
  background: #2a2a4e;
  border-color: #555;
}

.btn.colab {
  background: #1a3a1a;
  border-color: #2a5a2a;
}

.btn.colab:hover {
  background: #2a5a2a;
  border-color: #4a8a4a;
}

section {
  margin: 40px 0;
}

h2 {
  font-size: 1.3em;
  color: #ffffff;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid #222;
}

h3 {
  font-size: 1.15em;
  color: #ffffff;
  margin-bottom: 16px;
}

p {
  margin-bottom: 12px;
  color: #b0b0b0;
}

.action-box {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin: 16px 0;
}

.tag {
  display: inline-block;
  padding: 4px 14px;
  border-radius: 20px;
  background: #1a1a2e;
  border: 1px solid #333;
  font-size: 0.85em;
  font-family: "SF Mono", "Consolas", monospace;
  color: #99c;
}

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

.step {
  display: flex;
  gap: 16px;
  padding: 16px;
  border-radius: 8px;
  background: #111118;
  border: 1px solid #1a1a22;
  transition: all 0.2s;
}

.step.highlight {
  background: #12121e;
  border-color: #2a2a44;
}

.step-num {
  flex-shrink: 0;
  width: 70px;
  font-weight: 700;
  font-size: 0.85em;
  color: #6688cc;
  padding-top: 2px;
}

.step-body {
  flex: 1;
  font-size: 0.92em;
  color: #b0b0b0;
}

.step-body p {
  margin: 8px 0;
}

.step-body code {
  background: #1a1a2e;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.9em;
  color: #aaccff;
}

.result {
  margin-top: 8px;
  padding: 6px 12px;
  border-radius: 6px;
  background: #181822;
  font-size: 0.9em;
  color: #999;
}

.result.winner {
  border-left: 3px solid #4caf50;
  color: #81c784;
}

.result.insight {
  border-left: 3px solid #ff9800;
  color: #ffb74d;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 12px 0;
  font-size: 0.9em;
}

th, td {
  padding: 8px 12px;
  text-align: left;
  border-bottom: 1px solid #222;
}

th {
  color: #888;
  font-weight: 600;
  font-size: 0.85em;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

td.pass { color: #81c784; }
td.warn { color: #ffb74d; }
td.fail { color: #ef5350; }

.format-box {
  background: #1a1a2e;
  padding: 12px 16px;
  border-radius: 8px;
  margin: 12px 0;
  font-size: 0.9em;
  text-align: center;
}

.format-box .em {
  color: #ffb74d;
  font-weight: 600;
}

.example {
  margin: 16px 0;
  border-radius: 8px;
  overflow: hidden;
  border: 1px solid #222;
}

.example-header {
  padding: 10px 16px;
  font-weight: 600;
  font-size: 0.85em;
}

.example-header.wrong { background: #2a1010; color: #ef5350; }
.example-header.correct { background: #0a2a10; color: #81c784; }

.example-body {
  padding: 16px;
  background: #0e0e14;
}

.example-body p {
  margin-bottom: 4px;
  font-family: "SF Mono", "Consolas", monospace;
  font-size: 0.85em;
}

.bad { color: #ef5350; font-weight: 600; }
.good { color: #81c784; }

.note {
  color: #666 !important;
  font-family: inherit !important;
  font-size: 0.85em !important;
}

.insight {
  font-size: 1em;
  color: #ffb74d;
  font-weight: 500;
  text-align: center;
  padding: 16px;
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
}

.card {
  padding: 20px;
  background: #111118;
  border: 1px solid #1a1a22;
  border-radius: 8px;
}

.card-icon {
  font-size: 1.5em;
  margin-bottom: 8px;
}

.card h4 {
  color: #ffffff;
  margin-bottom: 8px;
  font-size: 0.95em;
}

.card p {
  font-size: 0.85em;
  color: #888;
}

pre {
  background: #0e0e14;
  padding: 20px;
  border-radius: 8px;
  overflow-x: auto;
  border: 1px solid #1a1a22;
}

code {
  font-family: "SF Mono", "Consolas", "Liberation Mono", monospace;
  font-size: 0.85em;
  color: #aaccff;
  line-height: 1.6;
}

footer {
  text-align: center;
  padding: 40px 0;
  color: #555;
  font-size: 0.85em;
}

footer a {
  color: #6688cc;
  text-decoration: none;
}

footer a:hover {
  text-decoration: underline;
}

a {
  color: #6688cc;
}

@media (max-width: 600px) {
  h1 { font-size: 1.3em; }
  .step { flex-direction: column; gap: 8px; }
  .step-num { width: auto; }
}