/* Kyukei Networking SCS2111 Design System */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=JetBrains+Mono:wght@400;500;600;700&family=Outfit:wght@400;600;700;800&display=swap');

:root {
  --bg-dark: #090d16;
  --bg-card: rgba(16, 23, 42, 0.75);
  --bg-card-hover: rgba(24, 35, 63, 0.85);
  --border-color: rgba(56, 189, 248, 0.15);
  --border-glow: rgba(56, 189, 248, 0.4);
  
  --primary-cyan: #38bdf8;
  --primary-blue: #3b82f6;
  --accent-purple: #818cf8;
  --accent-green: #34d399;
  --accent-amber: #fbbf24;
  --accent-rose: #f43f5e;
  
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  
  --font-main: 'Inter', system-ui, -apple-system, sans-serif;
  --font-heading: 'Outfit', 'Inter', sans-serif;
  --font-code: 'JetBrains Mono', monospace;
  
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  
  --shadow-glow: 0 0 25px rgba(56, 189, 248, 0.15);
  --shadow-card: 0 10px 30px -5px rgba(0, 0, 0, 0.5);
  --glass-blur: blur(12px);
}

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

body {
  background-color: var(--bg-dark);
  background-image: 
    radial-gradient(at 0% 0%, rgba(56, 189, 248, 0.08) 0px, transparent 50%),
    radial-gradient(at 100% 100%, rgba(129, 140, 248, 0.08) 0px, transparent 50%);
  color: var(--text-main);
  font-family: var(--font-main);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header & Navigation */
header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(9, 13, 22, 0.85);
  backdrop-filter: var(--glass-blur);
  border-bottom: 1px solid var(--border-color);
  padding: 0.8rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo-group {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text-main);
}

.logo-badge {
  background: linear-gradient(135deg, var(--primary-cyan), var(--primary-blue));
  color: #000;
  font-family: var(--font-heading);
  font-weight: 800;
  font-size: 0.85rem;
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  letter-spacing: 1px;
}

.logo-title {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.25rem;
  background: linear-gradient(135deg, #fff 30%, var(--primary-cyan));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 15px;
  list-style: none;
}

.nav-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  transition: all 0.2s ease;
  padding: 6px 12px;
  border-radius: var(--radius-sm);
}

.nav-links a:hover, .nav-links a.active {
  color: var(--primary-cyan);
  background: rgba(56, 189, 248, 0.1);
}

/* Layout container */
.app-container {
  display: flex;
  flex: 1;
  max-width: 1600px;
  margin: 0 auto;
  width: 100%;
}

aside.sidebar {
  width: 300px;
  background: rgba(16, 23, 42, 0.4);
  border-right: 1px solid var(--border-color);
  padding: 1.5rem 1rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.sidebar-title {
  font-family: var(--font-heading);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--text-dim);
  margin-bottom: 0.5rem;
  padding-left: 0.5rem;
}

.phase-nav {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.phase-nav a {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  border-radius: var(--radius-sm);
  transition: all 0.2s ease;
  border: 1px solid transparent;
}

.phase-nav a:hover {
  background: rgba(56, 189, 248, 0.08);
  color: var(--text-main);
  border-color: rgba(56, 189, 248, 0.2);
}

.phase-nav a.active {
  background: rgba(56, 189, 248, 0.15);
  color: var(--primary-cyan);
  border-color: rgba(56, 189, 248, 0.4);
  font-weight: 600;
}

.phase-num {
  font-family: var(--font-code);
  font-size: 0.75rem;
  background: rgba(255, 255, 255, 0.05);
  padding: 2px 6px;
  border-radius: 4px;
}

main.content-area {
  flex: 1;
  padding: 2rem 2.5rem;
  max-width: 1200px;
  overflow-y: auto;
}

/* Typography & Headings */
h1 {
  font-family: var(--font-heading);
  font-size: 2.2rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, #ffffff 0%, var(--primary-cyan) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

h2 {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  margin: 2rem 0 1rem;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 10px;
}

h2::before {
  content: '';
  display: inline-block;
  width: 4px;
  height: 1.2em;
  background: var(--primary-cyan);
  border-radius: 2px;
}

h3 {
  font-family: var(--font-heading);
  font-size: 1.2rem;
  font-weight: 600;
  margin: 1.5rem 0 0.8rem;
  color: var(--accent-purple);
}

p {
  margin-bottom: 1rem;
  color: var(--text-muted);
  font-size: 1rem;
}

/* Glass Cards & Containers */
.card {
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
  box-shadow: var(--shadow-card);
}

.card:hover {
  border-color: var(--border-glow);
}

.card.highlight {
  border-color: var(--primary-cyan);
  box-shadow: var(--shadow-glow);
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1.5rem;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.2rem;
}

/* Industrial Alert Callouts */
.callout {
  padding: 1.2rem;
  border-radius: var(--radius-md);
  margin: 1.5rem 0;
  border-left: 4px solid;
  background: rgba(15, 23, 42, 0.6);
}

.callout-info {
  border-color: var(--primary-cyan);
  background: rgba(56, 189, 248, 0.05);
}

.callout-warning {
  border-color: var(--accent-amber);
  background: rgba(251, 191, 36, 0.05);
}

.callout-work {
  border-color: var(--accent-green);
  background: rgba(52, 211, 153, 0.05);
}

.callout-title {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 0.95rem;
  margin-bottom: 0.4rem;
  display: flex;
  align-items: center;
  gap: 8px;
}

.callout-info .callout-title { color: var(--primary-cyan); }
.callout-warning .callout-title { color: var(--accent-amber); }
.callout-work .callout-title { color: var(--accent-green); }

/* Badges & Pills */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 3px 8px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
  font-family: var(--font-code);
  text-transform: uppercase;
}

.badge-cyan { background: rgba(56, 189, 248, 0.15); color: var(--primary-cyan); border: 1px solid rgba(56, 189, 248, 0.3); }
.badge-green { background: rgba(52, 211, 153, 0.15); color: var(--accent-green); border: 1px solid rgba(52, 211, 153, 0.3); }
.badge-amber { background: rgba(251, 191, 36, 0.15); color: var(--accent-amber); border: 1px solid rgba(251, 191, 36, 0.3); }
.badge-purple { background: rgba(129, 140, 248, 0.15); color: var(--accent-purple); border: 1px solid rgba(129, 140, 248, 0.3); }

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: var(--radius-sm);
  font-family: var(--font-main);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  border: none;
  transition: all 0.2s ease;
  text-decoration: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary-cyan), var(--primary-blue));
  color: #000;
  box-shadow: 0 4px 15px rgba(56, 189, 248, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(56, 189, 248, 0.4);
}

.btn-outline {
  background: transparent;
  color: var(--text-main);
  border: 1px solid var(--border-glow);
}

.btn-outline:hover {
  background: rgba(56, 189, 248, 0.1);
  border-color: var(--primary-cyan);
}

/* Code Blocks & CLI Command Containers */
pre, code {
  font-family: var(--font-code);
}

code.inline-code {
  background: rgba(255, 255, 255, 0.08);
  color: var(--primary-cyan);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.88em;
}

.code-block {
  background: #060911;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.2rem;
  margin: 1rem 0;
  overflow-x: auto;
  color: #e2e8f0;
  position: relative;
}

.code-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 0.8rem;
  margin-bottom: 0.8rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  font-size: 0.8rem;
  color: var(--text-dim);
}

/* Interactive Tabs */
.tab-container {
  margin: 1.5rem 0;
}

.tab-buttons {
  display: flex;
  gap: 8px;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 8px;
  overflow-x: auto;
}

.tab-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  padding: 8px 16px;
  font-family: var(--font-main);
  font-weight: 500;
  font-size: 0.9rem;
  cursor: pointer;
  border-radius: var(--radius-sm);
  transition: all 0.2s ease;
  white-space: nowrap;
}

.tab-btn.active {
  background: rgba(56, 189, 248, 0.15);
  color: var(--primary-cyan);
  font-weight: 600;
}

.tab-content {
  display: none;
  padding: 1.2rem 0;
}

.tab-content.active {
  display: block;
}

/* Footer */
footer {
  text-align: center;
  padding: 2rem;
  color: var(--text-dim);
  border-top: 1px solid var(--border-color);
  font-size: 0.85rem;
  margin-top: auto;
}