/* ============================================
   Bitcoin Learning Center — Global Styles
   ============================================ */

/* === Variables === */
:root {
  --bg-primary:    #0d1117;
  --bg-secondary:  #161b22;
  --bg-tertiary:   #21262d;
  --accent-orange: #f7931a;
  --accent-blue:   #58a6ff;
  --accent-green:  #3fb950;
  --accent-red:    #f85149;
  --accent-purple: #bc8cff;
  --text-primary:  #e6edf3;
  --text-secondary:#8b949e;
  --border:        #30363d;
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --transition: 200ms ease-out;
  --max-width: 960px;
}

/* === Reset === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; scroll-behavior: smooth; }
body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}
a { color: var(--accent-blue); text-decoration: none; }
a:hover { text-decoration: underline; }
img, svg { max-width: 100%; display: block; }
button { cursor: pointer; font-family: inherit; }
input, select, textarea { font-family: inherit; }

/* === Typography === */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 0.5em;
}
h1 { font-size: 2rem; color: var(--accent-orange); }
h2 { font-size: 1.5rem; color: var(--text-primary); }
h3 { font-size: 1.125rem; color: var(--text-primary); }
p { margin-bottom: 1em; color: var(--text-secondary); }
code, .mono { font-family: var(--font-mono); font-size: 0.9em; }
.hash, .address { font-family: var(--font-mono); font-size: 0.8rem; word-break: break-all; }

/* === Layout === */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1rem;
}
.page { padding: 5rem 0 3rem; }

/* === Header === */
.header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: rgba(13, 17, 23, 0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0.75rem 1rem;
}
.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--accent-orange);
}
.logo span { color: var(--text-primary); }
.logo:hover { text-decoration: none; }

.nav { display: flex; gap: 0.25rem; }
.nav-item {
  position: relative;
}
.nav-link {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: 0.875rem;
  font-weight: 500;
  transition: var(--transition);
}
.nav-link:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  text-decoration: none;
}
.nav-dropdown {
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 200px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 0.5rem;
  display: none;
  flex-direction: column;
  box-shadow: 0 8px 24px rgba(0,0,0,0.4);
}
.nav-item:hover .nav-dropdown { display: flex; }
.nav-dropdown a {
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 0.875rem;
  transition: var(--transition);
}
.nav-dropdown a:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  text-decoration: none;
}

.header-actions { display: flex; gap: 0.5rem; }

/* === Buttons === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 600;
  border: none;
  transition: var(--transition);
  cursor: pointer;
}
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

.btn-primary {
  background: var(--accent-orange);
  color: #000;
}
.btn-primary:hover:not(:disabled) { background: #e8850f; }

.btn-secondary {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border);
}
.btn-secondary:hover:not(:disabled) { border-color: var(--text-secondary); }

.btn-danger { background: var(--accent-red); color: #fff; }
.btn-success { background: var(--accent-green); color: #000; }
.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid transparent;
}
.btn-ghost:hover { background: var(--bg-tertiary); color: var(--text-primary); }

.btn-sm { padding: 0.25rem 0.5rem; font-size: 0.75rem; }
.btn-lg { padding: 0.75rem 1.5rem; font-size: 1rem; }
.btn-icon { padding: 0.5rem; min-width: 2.5rem; }

/* === Cards === */
.card {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.card-header {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 0.75rem;
}
.card-header h2, .card-header h3 { margin: 0; }
.card-body { padding: 1.25rem; }
.card-footer {
  padding: 0.75rem 1.25rem;
  border-top: 1px solid var(--border);
  background: var(--bg-tertiary);
}

/* === Stats Grid === */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 0.75rem;
}
.stat-card {
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  padding: 0.75rem 1rem;
  text-align: center;
}
.stat-value {
  font-family: var(--font-mono);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent-orange);
  display: block;
}
.stat-label {
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-top: 0.25rem;
}

/* === Tables === */
.table-wrap { overflow-x: auto; }
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
}
th {
  text-align: left;
  padding: 0.75rem 1rem;
  background: var(--bg-tertiary);
  color: var(--text-primary);
  font-weight: 600;
  border-bottom: 2px solid var(--border);
}
td {
  padding: 0.625rem 1rem;
  border-bottom: 1px solid var(--border);
  color: var(--text-secondary);
}
tr:hover td { background: rgba(255,255,255,0.02); }
.table-mono td { font-family: var(--font-mono); font-size: 0.8rem; }

/* === Forms === */
.form-group { margin-bottom: 1rem; }
.form-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.375rem;
}
.form-hint {
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-top: 0.25rem;
}

input[type="text"],
input[type="number"],
textarea,
select {
  width: 100%;
  padding: 0.5rem 0.75rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 0.875rem;
  transition: var(--transition);
}
input:focus, textarea:focus, select:focus {
  outline: none;
  border-color: var(--accent-blue);
  box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.15);
}
input[type="number"] { font-family: var(--font-mono); }

input[type="range"] {
  width: 100%;
  height: 6px;
  background: var(--bg-tertiary);
  border-radius: 3px;
  outline: none;
  -webkit-appearance: none;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px; height: 18px;
  background: var(--accent-orange);
  border-radius: 50%;
  cursor: pointer;
}

/* Number spinner */
.spinner-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.spinner-group input {
  text-align: center;
  width: 100px;
}
.spinner-group .btn { padding: 0.375rem 0.5rem; }

/* === Tabs === */
.tabs {
  display: flex;
  gap: 0.25rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 1.5rem;
}
.tab-btn {
  padding: 0.625rem 1rem;
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  color: var(--text-secondary);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
  margin-bottom: -1px;
}
.tab-btn:hover { color: var(--text-primary); }
.tab-btn.active {
  color: var(--accent-orange);
  border-bottom-color: var(--accent-orange);
}
.tab-content { display: none; }
.tab-content.active { display: block; }

/* === Badges === */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.125rem 0.5rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
}
.badge-orange { background: rgba(247, 147, 26, 0.15); color: var(--accent-orange); }
.badge-green  { background: rgba(63, 185, 80, 0.15);  color: var(--accent-green); }
.badge-red    { background: rgba(248, 81, 73, 0.15);   color: var(--accent-red); }
.badge-blue   { background: rgba(88, 166, 255, 0.15); color: var(--accent-blue); }
.badge-purple { background: rgba(188, 140, 255, 0.15);color: var(--accent-purple); }

/* === Progress Bar === */
.progress {
  height: 8px;
  background: var(--bg-tertiary);
  border-radius: 4px;
  overflow: hidden;
}
.progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-orange), #ffcc66);
  border-radius: 4px;
  transition: width 0.4s ease-out;
}

/* === Code Block === */
.code-block {
  background: #000;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-secondary);
  overflow-x: auto;
  position: relative;
}
.code-block .copy-btn {
  position: absolute;
  top: 0.5rem; right: 0.5rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.25rem 0.5rem;
  font-size: 0.7rem;
  color: var(--text-secondary);
  cursor: pointer;
}

/* === Breadcrumb === */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
}
.breadcrumb a { color: var(--text-secondary); }
.breadcrumb span { color: var(--accent-orange); }

/* === Highlight Colors === */
.txt-orange { color: var(--accent-orange); }
.txt-green  { color: var(--accent-green); }
.txt-red    { color: var(--accent-red); }
.txt-blue   { color: var(--accent-blue); }
.txt-purple { color: var(--accent-purple); }

/* === Alert / Note === */
.alert {
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  border-left: 3px solid;
  margin-bottom: 1rem;
  font-size: 0.875rem;
}
.alert-info    { background: rgba(88,166,255,0.1); border-color: var(--accent-blue); }
.alert-warning { background: rgba(247,147,26,0.1); border-color: var(--accent-orange); }
.alert-danger  { background: rgba(248,81,73,0.1);  border-color: var(--accent-red); }
.alert-success  { background: rgba(63,185,80,0.1);  border-color: var(--accent-green); }

/* === Animations === */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}
@keyframes countUp {
  from { opacity: 0.5; }
  to   { opacity: 1; }
}
.fade-in { animation: fadeIn 0.3s ease-out; }
.animate-count { animation: countUp 0.2s ease-out; }

/* === Footer === */
.footer {
  text-align: center;
  padding: 2rem 1rem;
  border-top: 1px solid var(--border);
  color: var(--text-secondary);
  font-size: 0.875rem;
}
.footer span { color: var(--accent-orange); }

/* === Responsive === */
@media (max-width: 768px) {
  .nav { display: none; } /* simplified mobile nav */
  .header-actions .btn span { display: none; }
  h1 { font-size: 1.5rem; }
  .card-body { padding: 1rem; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
}