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

:root {
  --bg: #fafbfc;
  --surface: #ffffff;
  --surface-hover: #f6f8fa;
  --border: #d1d9e0;
  --border-light: #e8ecf0;
  --text: #1f2937;
  --text-secondary: #586069;
  --text-muted: #656d76;
  --accent: #0969da;
  --accent-hover: #0550ae;
  --accent-subtle: #ddf4ff;
  --sidebar-bg: #f6f8fa;
  --green: #1a7f37;
  --green-bg: #dafbe1;
  --yellow: #9a6700;
  --yellow-bg: #fff8c5;
  --red: #cf222e;
  --red-bg: #ffebe9;
  --blue: #0969da;
  --blue-bg: #ddf4ff;
  --gray: #586069;
  --gray-bg: #eaeef2;
  --radius: 8px;
  --radius-sm: 6px;
  --shadow-sm: 0 1px 2px rgba(27, 31, 36, 0.04);
  --shadow: 0 1px 3px rgba(27, 31, 36, 0.06), 0 1px 2px rgba(27, 31, 36, 0.04);
}

html {
  font-size: 15px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Noto Sans, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

.layout {
  display: flex;
  min-height: 100vh;
}

.sidebar {
  width: 220px;
  background: var(--sidebar-bg);
  border-right: 1px solid var(--border);
  padding: 1.25rem 0;
  position: sticky;
  top: 0;
  height: 100vh;
  flex-shrink: 0;
  overflow-y: auto;
}

.sidebar-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0 1rem 1.25rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 0.75rem;
}

.logo {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  background: var(--accent);
  color: #fff;
  border-radius: var(--radius-sm);
  font-size: 0.7rem;
  font-weight: 700;
  font-family: "SF Mono", "Fira Code", monospace;
}

.logo-text {
  font-weight: 600;
  font-size: 0.9375rem;
  letter-spacing: -0.01em;
}

.nav-list {
  list-style: none;
  padding: 0 0.5rem;
}

.nav-link {
  display: block;
  padding: 0.4375rem 0.75rem;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  border-radius: var(--radius-sm);
  transition: background 0.15s, color 0.15s;
}

.nav-link:hover {
  background: var(--surface);
  color: var(--text);
}

.nav-link.active {
  background: var(--accent-subtle);
  color: var(--accent);
  font-weight: 500;
}

.content {
  flex: 1;
  padding: 2rem 2.5rem;
  max-width: 960px;
  min-width: 0;
}

.page-header {
  margin-bottom: 2rem;
}

.page-header h1 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.page-header p {
  color: var(--text-muted);
  font-size: 0.9375rem;
  margin-top: 0.25rem;
}

.component-section {
  margin-bottom: 2.5rem;
}

.section-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border-light);
}

.section-header h2 {
  font-size: 1.125rem;
  font-weight: 600;
}

.section-tag {
  font-size: 0.6875rem;
  font-weight: 500;
  color: var(--text-muted);
  background: var(--gray-bg);
  padding: 0.125rem 0.5rem;
  border-radius: 999px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.component-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
}

.component-grid--single {
  grid-template-columns: 1fr;
}

.preview-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.preview-card h3 {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-muted);
  padding: 0.75rem 1rem;
  background: var(--surface-hover);
  border-bottom: 1px solid var(--border-light);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.preview-area {
  padding: 1.25rem 1rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.625rem;
  align-items: flex-start;
}

.preview-area--align-end {
  align-items: flex-end;
}

.preview-area--stack {
  flex-direction: column;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, box-shadow 0.15s;
  font-family: inherit;
  line-height: 1.4;
  white-space: nowrap;
}

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

.btn-primary:hover:not(:disabled) {
  background: var(--accent-hover);
}

.btn-secondary {
  background: var(--surface);
  color: var(--text);
  border-color: var(--border);
}

.btn-secondary:hover:not(:disabled) {
  background: var(--surface-hover);
}

.btn-ghost {
  background: transparent;
  color: var(--accent);
  border-color: transparent;
}

.btn-ghost:hover:not(:disabled) {
  background: var(--accent-subtle);
}

.btn-danger {
  background: var(--red);
  color: #fff;
  border-color: var(--red);
}

.btn-danger:hover:not(:disabled) {
  background: #a40e26;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-sm {
  padding: 0.3125rem 0.625rem;
  font-size: 0.75rem;
}

.btn-lg {
  padding: 0.625rem 1.25rem;
  font-size: 1rem;
}

.btn-loading {
  position: relative;
  pointer-events: none;
}

.spinner {
  width: 14px;
  height: 14px;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-top-color: #fff;
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}

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

/* Inputs */
.field {
  width: 100%;
}

.field-label {
  display: block;
  font-size: 0.8125rem;
  font-weight: 500;
  margin-bottom: 0.375rem;
  color: var(--text);
}

.input {
  width: 100%;
  padding: 0.5rem 0.75rem;
  font-size: 0.875rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--text);
  transition: border-color 0.15s, box-shadow 0.15s;
  font-family: inherit;
  line-height: 1.4;
}

.input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(9, 105, 218, 0.15);
}

.input:disabled {
  background: var(--surface-hover);
  color: var(--text-muted);
  cursor: not-allowed;
}

.input-error {
  border-color: var(--red);
}

.input-error:focus {
  box-shadow: 0 0 0 3px rgba(207, 34, 46, 0.15);
}

.field-error {
  font-size: 0.75rem;
  color: var(--red);
  margin-top: 0.25rem;
  display: block;
}

.select {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg width='12' height='8' viewBox='0 0 12 8' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M1 1.5L6 6.5L11 1.5' stroke='%23586069' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.75rem center;
  padding-right: 2rem;
  cursor: pointer;
}

.toggle-row {
  display: flex;
  align-items: center;
  gap: 0.625rem;
}

.toggle {
  position: relative;
  display: inline-block;
  cursor: pointer;
}

.toggle input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.toggle-track {
  display: block;
  width: 36px;
  height: 20px;
  background: var(--border);
  border-radius: 10px;
  transition: background 0.2s;
  position: relative;
}

.toggle-track::after {
  content: "";
  position: absolute;
  width: 16px;
  height: 16px;
  background: #fff;
  border-radius: 50%;
  top: 2px;
  left: 2px;
  transition: transform 0.2s;
  box-shadow: var(--shadow-sm);
}

.toggle input:checked + .toggle-track {
  background: var(--accent);
}

.toggle input:checked + .toggle-track::after {
  transform: translateX(16px);
}

.toggle input:focus-visible + .toggle-track {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.toggle-label {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

/* Badges & Tags */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.125rem 0.5rem;
  font-size: 0.75rem;
  font-weight: 500;
  border-radius: 999px;
  line-height: 1.6;
}

.badge-green { background: var(--green-bg); color: var(--green); }
.badge-yellow { background: var(--yellow-bg); color: var(--yellow); }
.badge-red { background: var(--red-bg); color: var(--red); }
.badge-blue { background: var(--blue-bg); color: var(--blue); }
.badge-gray { background: var(--gray-bg); color: var(--gray); }

.tag {
  display: inline-flex;
  align-items: center;
  padding: 0.1875rem 0.625rem;
  font-size: 0.75rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  background: var(--accent-subtle);
  color: var(--accent);
  border: 1px solid transparent;
  transition: border-color 0.15s;
}

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

/* Cards (demo) */
.demo-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
  width: 100%;
}

.demo-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.5rem;
}

.demo-card-body {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.demo-card-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 0.75rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border-light);
}

.demo-card-meta {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.demo-stat-row {
  display: flex;
  gap: 1rem;
  width: 100%;
}

.demo-stat {
  flex: 1;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.875rem;
  text-align: center;
}

.demo-stat-value {
  display: block;
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.demo-stat-label {
  display: block;
  font-size: 0.6875rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-top: 0.125rem;
}

.demo-stat-change {
  display: block;
  font-size: 0.6875rem;
  font-weight: 500;
  margin-top: 0.25rem;
}

.demo-stat-change.positive { color: var(--green); }
.demo-stat-change.negative { color: var(--red); }

/* Alerts */
.alert {
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  line-height: 1.5;
  border-left: 3px solid;
}

.alert-info { background: var(--blue-bg); border-color: var(--blue); color: #0a3069; }
.alert-success { background: var(--green-bg); border-color: var(--green); color: #0a3622; }
.alert-warning { background: var(--yellow-bg); border-color: var(--yellow); color: #4d2d00; }
.alert-error { background: var(--red-bg); border-color: var(--red); color: #82071e; }

/* Progress */
.progress-group {
  width: 100%;
}

.progress-group + .progress-group {
  margin-top: 0.75rem;
}

.progress-header {
  display: flex;
  justify-content: space-between;
  font-size: 0.8125rem;
  margin-bottom: 0.375rem;
  color: var(--text-secondary);
}

.progress-bar {
  width: 100%;
  height: 8px;
  background: var(--gray-bg);
  border-radius: 4px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--green);
  border-radius: 4px;
  transition: width 0.6s ease;
}

.progress-fill--blue { background: var(--blue); }
.progress-fill--red { background: var(--red); }

/* Skeleton */
.skeleton-group {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
  width: 100%;
}

.skeleton {
  background: linear-gradient(90deg, var(--gray-bg) 25%, #f0f3f6 50%, var(--gray-bg) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: var(--radius-sm);
}

.skeleton--circle {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  flex-shrink: 0;
}

.skeleton-lines {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.skeleton--line {
  height: 12px;
}

.skeleton--w90 { width: 90%; }
.skeleton--w60 { width: 60%; }
.skeleton--w40 { width: 40%; }

@keyframes shimmer {
  to { background-position: -200% 0; }
}

/* Responsive */
@media (max-width: 768px) {
  .sidebar {
    display: none;
  }

  .content {
    padding: 1.25rem 1rem;
  }

  .component-grid {
    grid-template-columns: 1fr;
  }

  .demo-stat-row {
    flex-direction: column;
  }
}