/* ========================================================
   STUDY:NLINK - Interactive Gamified Learning Hub
   Palette: Deep Slate (#060911, #0c1322), Neon Cyan & Amber
   ======================================================== */

:root {
  --font-sans: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, 'Helvetica Neue', 'Segoe UI', 'Apple SD Gothic Neo', 'Noto Sans KR', sans-serif;
  --font-mono: 'JetBrains Mono', 'Pretendard', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

  --bg-space: #060911;
  --bg-deep: #0c1322;
  --bg-card: rgba(17, 24, 39, 0.82);
  --bg-card-hover: rgba(22, 34, 56, 0.94);
  
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-cyan: rgba(34, 211, 238, 0.35);
  --border-amber: rgba(245, 158, 11, 0.35);
  --border-purple: rgba(168, 85, 247, 0.35);

  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  
  --cyan-400: #22d3ee;
  --cyan-500: #06b6d4;
  --emerald-400: #34d399;
  --emerald-500: #10b981;
  --amber-400: #fbbf24;
  --amber-500: #f59e0b;
  --purple-400: #c084fc;
  --purple-500: #a855f7;
  --rose-400: #fb7185;
  --rose-500: #f43f5e;

  --glow-cyan: 0 0 25px rgba(6, 182, 212, 0.35);
  --glow-amber: 0 0 25px rgba(245, 158, 11, 0.35);
  --glow-purple: 0 0 25px rgba(168, 85, 247, 0.35);

  --radius-lg: 20px;
  --radius-md: 12px;
  --radius-sm: 8px;
  --transition: all 0.24s cubic-bezier(0.16, 1, 0.3, 1);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

html, body {
  width: 100%;
  min-height: 100%;
  font-family: var(--font-sans);
  background-color: var(--bg-space);
  color: var(--text-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  letter-spacing: -0.015em;
  overflow-x: hidden;
  position: relative;
}

/* Subtle Tactical Grid Backdrop */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  background-size: 36px 36px;
  background-image: 
    linear-gradient(to right, rgba(56, 189, 248, 0.035) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(56, 189, 248, 0.035) 1px, transparent 1px);
  pointer-events: none;
  z-index: 0;
}

/* Ambient Neon Gradient Orbs */
.ambient-glow {
  position: fixed;
  width: 480px;
  height: 480px;
  border-radius: 50%;
  filter: blur(120px);
  opacity: 0.18;
  pointer-events: none;
  z-index: 0;
  transition: transform 1.2s ease;
}

.glow-cyan {
  top: -120px;
  left: -80px;
  background: radial-gradient(circle, var(--cyan-400) 0%, transparent 70%);
}

.glow-amber {
  bottom: 10%;
  right: -100px;
  background: radial-gradient(circle, var(--amber-400) 0%, transparent 70%);
}

/* Layout Container */
.layout-container {
  position: relative;
  z-index: 1;
  max-width: 1160px;
  margin: 0 auto;
  padding: 24px 20px 60px;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* ── Top Header ───────────────────────────────────── */
.hub-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 18px;
  background: rgba(12, 19, 34, 0.75);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-subtle);
  border-radius: 999px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
  margin-bottom: 48px;
}

.brand-group {
  display: flex;
  align-items: center;
  gap: 10px;
}

.brand-symbol {
  font-size: 22px;
  line-height: 1;
  filter: drop-shadow(0 0 8px rgba(34, 211, 238, 0.5));
}

.brand-text {
  display: flex;
  flex-direction: column;
}

.brand-title {
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: 15px;
  letter-spacing: 0.05em;
  color: #ffffff;
}

.brand-title .accent-dot {
  color: var(--cyan-400);
}

.brand-sub {
  font-size: 9.5px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

.status-indicator {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  background: rgba(16, 185, 129, 0.12);
  border: 1px solid rgba(16, 185, 129, 0.3);
  border-radius: 999px;
}

.pulse-dot {
  width: 6px;
  height: 6px;
  background-color: var(--emerald-400);
  border-radius: 50%;
  box-shadow: 0 0 8px var(--emerald-400);
  animation: livePulse 1.8s infinite;
}

@keyframes livePulse {
  0%, 100% { transform: scale(1); opacity: 1; }
  50% { transform: scale(1.4); opacity: 0.4; }
}

.status-label {
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 700;
  color: var(--emerald-400);
  letter-spacing: 0.04em;
}

/* ── Hero Section ─────────────────────────────────── */
.hero-section {
  text-align: center;
  margin-bottom: 56px;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.hero-pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(34, 211, 238, 0.08);
  border: 1px solid rgba(34, 211, 238, 0.3);
  color: var(--cyan-400);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  padding: 5px 14px;
  border-radius: 999px;
  box-shadow: 0 0 16px rgba(6, 182, 212, 0.15);
  margin-bottom: 20px;
}

.hero-title {
  font-size: clamp(28px, 4.8vw, 48px);
  font-weight: 900;
  line-height: 1.25;
  letter-spacing: -0.03em;
  margin-bottom: 18px;
  color: #ffffff;
}

.gradient-text {
  background: linear-gradient(135deg, #22d3ee 0%, #38bdf8 50%, #f59e0b 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  display: inline-block;
}

.hero-desc {
  font-size: clamp(14px, 1.8vw, 17px);
  color: var(--text-secondary);
  line-height: 1.65;
  max-width: 680px;
  margin-bottom: 32px;
}

.hero-actions {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
  justify-content: center;
}

.btn-hero-primary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: linear-gradient(135deg, #0284c7 0%, #0891b2 100%);
  border: 1px solid rgba(34, 211, 238, 0.4);
  color: #ffffff;
  padding: 12px 24px;
  border-radius: 999px;
  font-size: 14.5px;
  font-weight: 800;
  cursor: pointer;
  box-shadow: 0 4px 20px rgba(6, 182, 212, 0.4);
  transition: var(--transition);
}

.btn-hero-primary:hover {
  background: linear-gradient(135deg, #06b6d4 0%, #0284c7 100%);
  transform: translateY(-2px);
  box-shadow: 0 8px 26px rgba(6, 182, 212, 0.55);
}

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

.btn-hero-secondary {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(30, 41, 59, 0.6);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  padding: 12px 20px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 700;
  text-decoration: none;
  transition: var(--transition);
}

.btn-hero-secondary:hover {
  background: rgba(51, 65, 85, 0.7);
  color: #ffffff;
  border-color: rgba(255, 255, 255, 0.2);
  transform: translateY(-2px);
}

/* ── Missions Showcase ────────────────────────────── */
.missions-section {
  margin-bottom: 60px;
}

.section-head {
  margin-bottom: 28px;
}

.section-tag {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.1em;
  color: var(--cyan-400);
  display: block;
  margin-bottom: 4px;
}

.section-title {
  font-size: clamp(20px, 3vw, 28px);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: #ffffff;
}

.section-desc {
  font-size: 14px;
  color: var(--text-muted);
  margin-top: 4px;
}

/* 2x2 Responsive Mission Grid */
.mission-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 22px;
}

@media (max-width: 768px) {
  .mission-grid {
    grid-template-columns: 1fr;
    gap: 18px;
  }
}

/* Mission Card */
.mission-card {
  position: relative;
  background: var(--bg-card);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 26px 24px;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  box-shadow: 0 16px 36px rgba(0, 0, 0, 0.45);
  transition: transform 0.28s cubic-bezier(0.16, 1, 0.3, 1),
              border-color 0.28s ease,
              box-shadow 0.28s ease;
  transform-style: preserve-3d;
}

.mission-card:hover {
  transform: translateY(-4px);
  background: var(--bg-card-hover);
}

/* Card Glow Accent Styles */
.card-math:hover {
  border-color: var(--border-cyan);
  box-shadow: 0 20px 48px rgba(0, 0, 0, 0.6), 0 0 30px rgba(6, 182, 212, 0.18);
}

.card-geo:hover {
  border-color: var(--border-amber);
  box-shadow: 0 20px 48px rgba(0, 0, 0, 0.6), 0 0 30px rgba(245, 158, 11, 0.18);
}

.card-typing:hover {
  border-color: var(--border-purple);
  box-shadow: 0 20px 48px rgba(0, 0, 0, 0.6), 0 0 30px rgba(168, 85, 247, 0.18);
}

/* Dynamic Spotlight Cursor Glow */
.card-glow-layer {
  position: absolute;
  inset: 0;
  border-radius: inherit;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.3s ease;
  z-index: 1;
}

.mission-card:hover .card-glow-layer {
  opacity: 1;
}

.card-inner {
  position: relative;
  z-index: 2;
  display: flex;
  flex-direction: column;
  height: 100%;
}

.card-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.card-badge-group {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.mission-badge {
  font-size: 11px;
  font-weight: 700;
  padding: 3.5px 9px;
  border-radius: 999px;
  white-space: nowrap;
}

.badge-math {
  background: rgba(6, 182, 212, 0.15);
  border: 1px solid rgba(6, 182, 212, 0.35);
  color: var(--cyan-400);
}

.badge-geo {
  background: rgba(56, 189, 248, 0.15);
  border: 1px solid rgba(56, 189, 248, 0.35);
  color: #7dd3fc;
}

.badge-typing {
  background: rgba(168, 85, 247, 0.15);
  border: 1px solid rgba(168, 85, 247, 0.35);
  color: var(--purple-400);
}

.badge-upcoming {
  background: rgba(148, 163, 184, 0.15);
  border: 1px solid rgba(148, 163, 184, 0.3);
  color: #e2e8f0;
}

.badge-hot {
  background: rgba(245, 158, 11, 0.15);
  border: 1px solid rgba(245, 158, 11, 0.35);
  color: var(--amber-400);
}

.mission-num {
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 800;
  color: rgba(255, 255, 255, 0.2);
}

.card-main {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 14px;
}

.card-icon-wrap {
  width: 52px;
  height: 52px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 26px;
  flex-shrink: 0;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.4);
}

.icon-math {
  background: linear-gradient(135deg, rgba(6, 182, 212, 0.2), rgba(16, 185, 129, 0.2));
  border: 1px solid rgba(34, 211, 238, 0.4);
  box-shadow: 0 0 16px rgba(6, 182, 212, 0.25);
}

.icon-geo {
  background: linear-gradient(135deg, rgba(56, 189, 248, 0.2), rgba(245, 158, 11, 0.2));
  border: 1px solid rgba(56, 189, 248, 0.4);
  box-shadow: 0 0 16px rgba(56, 189, 248, 0.25);
}

.icon-typing {
  background: linear-gradient(135deg, rgba(168, 85, 247, 0.2), rgba(99, 102, 241, 0.2));
  border: 1px solid rgba(168, 85, 247, 0.4);
  box-shadow: 0 0 16px rgba(168, 85, 247, 0.25);
}

.icon-upcoming {
  background: rgba(30, 41, 59, 0.6);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.card-title {
  font-family: var(--font-mono);
  font-size: 19px;
  font-weight: 800;
  color: #ffffff;
  letter-spacing: -0.01em;
}

.card-subtitle {
  font-size: 12.5px;
  font-weight: 600;
  color: var(--text-muted);
  margin-top: 2px;
}

.card-desc {
  font-size: 13.5px;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 20px;
  flex: 1;
}

.card-features {
  display: flex;
  flex-direction: column;
  gap: 7px;
  margin-bottom: 24px;
}

.feature-chip {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12.5px;
  font-weight: 600;
  color: #e2e8f0;
  padding: 6px 10px;
  background: rgba(30, 41, 59, 0.5);
  border-radius: var(--radius-sm);
  border-left: 2.5px solid var(--cyan-400);
}

.card-geo .feature-chip {
  border-left-color: var(--amber-400);
}

.card-typing .feature-chip {
  border-left-color: var(--purple-400);
}

/* Card Launch Buttons */
.card-footer {
  margin-top: auto;
}

.btn-card-launch {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: 12px 18px;
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 800;
  text-decoration: none;
  color: #ffffff;
  transition: var(--transition);
}

.btn-math {
  background: linear-gradient(135deg, #0284c7 0%, #0891b2 100%);
  border: 1px solid rgba(34, 211, 238, 0.4);
  box-shadow: 0 4px 16px rgba(6, 182, 212, 0.3);
}

.btn-math:hover {
  background: linear-gradient(135deg, #06b6d4 0%, #0284c7 100%);
  box-shadow: 0 6px 22px rgba(6, 182, 212, 0.5);
  transform: translateY(-1px);
}

.btn-geo {
  background: linear-gradient(135deg, #0284c7 0%, #d97706 100%);
  border: 1px solid rgba(245, 158, 11, 0.4);
  box-shadow: 0 4px 16px rgba(245, 158, 11, 0.3);
}

.btn-geo:hover {
  background: linear-gradient(135deg, #0ea5e9 0%, #f59e0b 100%);
  box-shadow: 0 6px 22px rgba(245, 158, 11, 0.5);
  transform: translateY(-1px);
}

.btn-typing {
  background: linear-gradient(135deg, #7c3aed 0%, #4f46e5 100%);
  border: 1px solid rgba(168, 85, 247, 0.4);
  box-shadow: 0 4px 16px rgba(168, 85, 247, 0.3);
}

.btn-typing:hover {
  background: linear-gradient(135deg, #9333ea 0%, #6366f1 100%);
  box-shadow: 0 6px 22px rgba(168, 85, 247, 0.5);
  transform: translateY(-1px);
}

.launch-arrow {
  transition: transform 0.2s ease;
}

.btn-card-launch:hover .launch-arrow {
  transform: translateX(4px);
}

/* Keyboard Shortcut Badges */
.kbd-hint {
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 700;
  padding: 2.5px 7px;
  border-radius: 4px;
  background: rgba(0, 0, 0, 0.4);
  border: 1px solid rgba(255, 255, 255, 0.18);
  color: var(--text-secondary);
  letter-spacing: 0.04em;
  margin-left: auto;
  margin-right: 8px;
  display: inline-flex;
  align-items: center;
  transition: var(--transition);
}

.btn-card-launch:hover .kbd-hint,
.btn-hero-primary:hover .kbd-hint {
  border-color: rgba(255, 255, 255, 0.45);
  color: #ffffff;
}

@media (max-width: 640px) {
  .kbd-hint {
    display: none;
  }
}

/* Upcoming Card Extras */
.upcoming-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 24px;
}

.upcoming-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 14px;
  background: rgba(30, 41, 59, 0.4);
  border: 1px dashed rgba(255, 255, 255, 0.12);
  border-radius: var(--radius-sm);
}

.upcoming-item .u-icon {
  font-size: 20px;
}

.upcoming-item strong {
  display: block;
  font-size: 13px;
  color: #ffffff;
  font-family: var(--font-mono);
}

.upcoming-item small {
  font-size: 11.5px;
  color: var(--text-muted);
}

.upcoming-notice {
  width: 100%;
  text-align: center;
  padding: 12px;
  background: rgba(30, 41, 59, 0.35);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  color: var(--text-muted);
  letter-spacing: 0.05em;
}

/* ── Footer ───────────────────────────────────────── */
.hub-footer {
  margin-top: auto;
  border-top: 1px solid var(--border-subtle);
  padding-top: 32px;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 20px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}

.footer-brand {
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 800;
  color: #ffffff;
  letter-spacing: 0.05em;
}

.footer-desc {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 4px;
}

.footer-links {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.footer-links a {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 0.15s ease;
}

.footer-links a:hover {
  color: var(--cyan-400);
}

.footer-bottom {
  font-size: 12px;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 8px;
}

.footer-dot {
  opacity: 0.5;
}

@media (max-width: 640px) {
  .hero-title {
    font-size: 26px;
  }
  .desktop-only {
    display: none;
  }
  .hub-header {
    margin-bottom: 32px;
  }
  .mission-card {
    padding: 20px 18px;
  }
  .footer-content {
    flex-direction: column;
  }
}