/* WhatKnot - Tactical CSS Theme v1.0 */
/* Dark military aesthetic with tactical HUD elements */

:root {
  /* Core tactical palette */
  --bg-dark: #0a0f14;
  --bg-darker: #05080b;
  --bg-panel: #11181f;
  --bg-card: #1a2330;
  
  --accent-green: #4ade80;
  --accent-green-dim: #2d5a3e;
  --accent-blue: #3b82f6;
  --accent-orange: #f97316;
  --accent-rank: #fbbf24;
  
  --text-primary: #e2e8f0;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --text-warn: #f8fafc;
  
  /* Difficulty colors */
  --diff-beginner: #10b981;
  --diff-intermediate: #f59e0b;
  --diff-advanced: #ef4444;
  
  /* Effects */
  --glow-green: 0 0 8px #4ade80;
  --glow-blue: 0 0 8px #3b82f6;
  --glow-rank: 0 0 12px #fbbf24;
  
  /* Responsive */
  --sidebar-width: 320px;
  --border-radius: 8px;
}

body[data-theme="light"] {
  --bg-dark: #f8fafc;
  --bg-darker: #f1f5f9;
  --bg-panel: #e2e8f0;
  --bg-card: #ffffff;
  --text-primary: #0f172a;
  --text-secondary: #334155;
  --text-muted: #64748b;
}

/* Light theme override */
[data-theme="light"] {
  --bg-dark: #f8fafc;
  --bg-darker: #f1f5f9;
  --bg-panel: #e2e8f0;
  --bg-card: #ffffff;
  --text-primary: #0f172a;
  --text-secondary: #334155;
  --text-muted: #64748b;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  background: var(--bg-dark);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  min-height: 100vh;
}

/* ═ Intro Screen ═══════════════════════════════════════════════ */
#intro-screen {
  height: 100vh;
  background: linear-gradient(135deg, var(--bg-darker) 0%, var(--bg-dark) 100%);
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.intro-bg {
  position: absolute;
  inset: 0;
  background-image: 
    radial-gradient(circle at 20% 80%, rgba(74, 222, 128, 0.05) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(59, 130, 246, 0.03) 0%, transparent 50%);
  animation: introPulse 4s ease-in-out infinite;
}

.intro-grid {
  position: absolute;
  inset: 0;
  background-image: 
    linear-gradient(rgba(20, 30, 48, 0.3) 1px, transparent 1px),
    linear-gradient(90deg, rgba(20, 30, 48, 0.3) 1px, transparent 1px);
  background-size: 40px 40px;
  animation: gridShift 20s linear infinite;
}

.intro-scanlines {
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(
    0deg,
    transparent,
    transparent 2px,
    rgba(255,255,255,0.02) 2px,
    rgba(255,255,255,0.02) 4px
  );
  pointer-events: none;
}

.intro-corner {
  position: absolute;
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  opacity: 0.8;
  font-family: 'Courier New', monospace;
}

.intro-corner.tl { top: 2rem; left: 2rem; }
.intro-corner.tr { top: 2rem; right: 2rem; text-align: right; }
.intro-corner.bl { bottom: 2rem; left: 2rem; }
.intro-corner.br { bottom: 2rem; right: 2rem; text-align: right; }

.intro-content {
  text-align: center;
  max-width: 600px;
  z-index: 10;
  animation: introFadeIn 1.5s ease-out 0.5s both;
}

.intro-eyebrow {
  font-size: 0.9rem;
  color: var(--text-muted);
  letter-spacing: 0.1em;
  margin-bottom: 0.5rem;
}

.intro-logo {
  font-size: clamp(3rem, 8vw, 6rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 0.25em;
  background: linear-gradient(135deg, var(--accent-green), var(--accent-blue));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.intro-logo span {
  color: var(--text-primary);
  font-weight: 400;
}

.intro-tagline {
  font-size: 1.3rem;
  font-weight: 400;
  color: var(--text-secondary);
  margin-bottom: 2rem;
  letter-spacing: -0.01em;
}

.begin-btn {
  background: linear-gradient(135deg, var(--bg-card), var(--bg-panel));
  border: 1px solid rgba(74, 222, 128, 0.3);
  color: var(--accent-green);
  padding: 1rem 2.5rem;
  font-size: 1.1rem;
  font-weight: 600;
  border-radius: var(--border-radius);
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 4px 20px rgba(0,0,0,0.3);
  position: relative;
  overflow: hidden;
}

.begin-btn:hover {
  box-shadow: var(--glow-green), 0 8px 32px rgba(0,0,0,0.4);
  transform: translateY(-2px);
  border-color: var(--accent-green);
}

.begin-btn:active {
  transform: translateY(0);
}

/* ═ Main Layout ═══════════════════════════════════════════════ */
#app {
  display: none;
  min-height: 100vh;
  position: relative;
}

#app.show {
  display: flex;
}

/* Sidebar */
#sidebar {
  width: var(--sidebar-width);
  background: var(--bg-panel);
  border-right: 1px solid rgba(255,255,255,0.05);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  position: fixed;
  height: 100vh;
  z-index: 100;
  box-shadow: 2px 0 20px rgba(0,0,0,0.3);
}

.sidebar-header {
  padding: 2rem 1.5rem 1.5rem;
  border-bottom: 1px solid rgba(255,255,255,0.05);
}

.sidebar-logo {
  font-size: 1.8rem;
  font-weight: 800;
  margin-bottom: 0.25rem;
}

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

.sidebar-sub {
  color: var(--text-muted);
  font-size: 0.85rem;
  letter-spacing: 0.05em;
}

/* HUD Section */
.hud-section {
  padding: 1.5rem;
  background: linear-gradient(180deg, rgba(74,222,128,0.05) 0%, transparent 100%);
}

.hud-rank-display {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1rem;
}

.hud-rank-icon {
  font-size: 2rem;
  background: radial-gradient(circle, var(--accent-rank), transparent);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(var(--glow-rank));
}

.hud-rank-name {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-primary);
}

.hud-xp {
  color: var(--text-muted);
  font-size: 0.9rem;
}

.progress-track {
  height: 6px;
  background: rgba(255,255,255,0.1);
  border-radius: 3px;
  overflow: hidden;
  margin: 0.75rem 0;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-green), var(--accent-blue));
  border-radius: 3px;
  transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: var(--glow-green);
}

.hud-learned-row {
  display: flex;
  justify-content: space-between;
  margin: 1rem 0 0.5rem;
  font-size: 0.9rem;
  color: var(--text-muted);
}

.hud-next {
  font-size: 0.8rem;
  color: var(--text-secondary);
  font-weight: 500;
}

/* Sections */
.ach-section, .stats-section {
  padding: 1.5rem;
  flex: 1;
  overflow-y: auto;
}

.section-header {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 1rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

/* Achievement Grid */
#achievement-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(80px, 1fr));
  gap: 0.75rem;
}

.achievement {
  aspect-ratio: 1;
  border-radius: 6px;
  background: var(--bg-card);
  border: 1px solid rgba(255,255,255,0.1);
  cursor: pointer;
  transition: all 0.2s;
  position: relative;
  overflow: hidden;
}

.achievement.unlocked {
  border-color: var(--accent-green);
  box-shadow: var(--glow-green);
}

.achievement.unlocked::after {
  content: '⬡';
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  opacity: 0.3;
}

/* Stats */
.stat-row {
  display: flex;
  justify-content: space-between;
  margin-bottom: 0.75rem;
  font-size: 0.9rem;
}

.stat-label {
  font-weight: 500;
}

/* Sidebar Footer */
.sidebar-footer {
  padding: 1.5rem;
  border-top: 1px solid rgba(255,255,255,0.05);
  padding-top: 2rem;
}

#theme-toggle {
  width: 100%;
  padding: 0.75rem;
  background: var(--bg-card);
  border: 1px solid rgba(255,255,255,0.1);
  color: var(--text-primary);
  border-radius: var(--border-radius);
  cursor: pointer;
  transition: all 0.2s;
}

#theme-toggle:hover {
  background: var(--accent-green-dim);
  border-color: var(--accent-green);
}

/* Main Content */
#main {
  flex: 1;
  margin-left: var(--sidebar-width);
  min-height: 100vh;
  position: relative;
}

/* Topbar */
#topbar {
  position: sticky;
  top: 0;
  background: rgba(10, 15, 20, 0.95);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(255,255,255,0.05);
  padding: 1rem 2rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  z-index: 50;
}

#sidebar-toggle {
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 1.2rem;
  cursor: pointer;
  padding: 0.5rem;
  border-radius: 4px;
  transition: 0.2s;
}

#sidebar-toggle:hover {
  background: rgba(255,255,255,0.1);
}

.search-wrap {
  flex: 1;
  max-width: 400px;
  position: relative;
}

#search-input {
  width: 100%;
  padding: 0.75rem 1rem 0.75rem 2.5rem;
  background: var(--bg-card);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: var(--border-radius);
  color: var(--text-primary);
  font-size: 0.95rem;
}

#search-input:focus {
  outline: none;
  border-color: var(--accent-green);
  box-shadow: var(--glow-green);
}

.search-icon {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
}

.topbar-controls {
  display: flex;
  gap: 1rem;
  align-items: center;
}

#sort-select, #show-favorites {
  padding: 0.5rem 1rem;
  background: var(--bg-card);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: var(--border-radius);
  color: var(--text-primary);
  cursor: pointer;
}

/* Filter Bar */
#filter-bar {
  background: var(--bg-darker);
  padding: 1rem 2rem;
  border-bottom: 1px solid rgba(255,255,255,0.05);
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
  overflow-x: auto;
}

.filter-label {
  font-weight: 500;
  color: var(--text-secondary);
  white-space: nowrap;
}

.diff-filter, .tag-filter {
  padding: 0.4rem 0.8rem;
  background: var(--bg-card);
  border: 1px solid transparent;
  border-radius: 20px;
  cursor: pointer;
  font-size: 0.85rem;
  transition: all 0.2s;
}

.diff-filter.active, .tag-filter.active {
  background: var(--accent-green);
  color: #000;
  border-color: var(--accent-green);
  box-shadow: var(--glow-green);
}

.filter-sep {
  width: 1px;
  height: 20px;
  background: rgba(255,255,255,0.2);
}

/* Count Bar */
#count-bar {
  padding: 0.75rem 2rem;
  background: var(--bg-darker);
  border-bottom: 1px solid rgba(255,255,255,0.05);
  font-weight: 500;
}

/* Knot Grid */
#knot-grid {
  padding: 2rem;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.5rem;
  max-width: 1400px;
  margin: 0 auto;
}

.knot-card {
  background: var(--bg-card);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: var(--border-radius);
  overflow: hidden;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
}

.knot-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 20px 40px rgba(0,0,0,0.3);
  border-color: rgba(74,222,128,0.3);
}

.knot-card.learned {
  border-left: 4px solid var(--accent-green);
}

.knot-header {
  padding: 1.25rem;
  border-bottom: 1px solid rgba(255,255,255,0.05);
}

.knot-difficulty {
  display: inline-block;
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.diff-beginner { background: rgba(16,185,129,0.2); color: var(--diff-beginner); }
.diff-intermediate { background: rgba(245,158,11,0.2); color: var(--diff-intermediate); }
.diff-advanced { background: rgba(239,68,68,0.2); color: var(--diff-advanced); }

.knot-name {
  font-size: 1.4rem;
  font-weight: 700;
  margin-top: 0.5rem;
  margin-bottom: 0.25rem;
}

.knot-tags {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-top: 0.5rem;
}

.tag {
  font-size: 0.75rem;
  padding: 0.2rem 0.5rem;
  background: rgba(255,255,255,0.1);
  border-radius: 12px;
}

.knot-footer {
  padding: 1rem 1.25rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.9rem;
  color: var(--text-muted);
}

.knot-xp {
  font-weight: 600;
  color: var(--accent-green);
}

/* Detail Panel */
#detail-panel {
  position: fixed;
  top: 0;
  right: -100%;
  width: 500px;
  height: 100vh;
  background: var(--bg-panel);
  border-left: 1px solid rgba(255,255,255,0.1);
  z-index: 200;
  transition: right 0.4s cubic-bezier(0,0,0.2,1);
  overflow-y: auto;
}

#detail-panel.show {
  right: 0;
}

.detail-header {
  position: sticky;
  top: 0;
  background: var(--bg-darker);
  padding: 1.5rem;
  border-bottom: 1px solid rgba(255,255,255,0.05);
}

.detail-close {
  position: absolute;
  top: 1.5rem;
  right: 1.5rem;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--text-muted);
  cursor: pointer;
}

.detail-steps {
  padding: 1.5rem;
}

.step {
  margin-bottom: 1.5rem;
  padding: 1rem;
  background: var(--bg-card);
  border-radius: var(--border-radius);
  border-left: 3px solid var(--accent-green);
}

/* Animations */
@keyframes introPulse {
  0%, 100% { opacity: 0.5; }
  50% { opacity: 1; }
}

@keyframes gridShift {
  0% { transform: translate(0, 0); }
  100% { transform: translate(40px, 40px); }
}

@keyframes introFadeIn {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Responsive */
@media (max-width: 1024px) {
  :root { --sidebar-width: 280px; }
}

@media (max-width: 768px) {
  #sidebar {
    transform: translateX(-100%);
    transition: transform 0.3s;
  }
  
  #sidebar.show {
    transform: translateX(0);
  }
  
  #main {
    margin-left: 0;
  }
  
  #topbar {
    padding: 1rem;
  }
  
  #knot-grid {
    padding: 1rem;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1rem;
  }
  
  #filter-bar {
    padding: 1rem;
    gap: 0.5rem;
  }
}

@media (max-width: 480px) {
  #knot-grid {
    grid-template-columns: 1fr;
  }
  
  #topbar {
    flex-direction: column;
    gap: 0.75rem;
    align-items: stretch;
  }
  
  .search-wrap {
    max-width: none;
    order: 3;
  }
  
  .topbar-controls {
    order: 2;
  }
  
  #sidebar-toggle {
    order: 1;
    align-self: flex-start;
  }
}

/* Utilities */
.text-glow { text-shadow: var(--glow-green); }
.hidden { display: none !important; }