/* ========================================
   TeKnowlogy Landing — Design System
   ======================================== */

/* --- Reset & Base --- */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --bg-dark: #0a0a12;
  --bg-card: rgba(255, 255, 255, 0.04);
  --bg-card-hover: rgba(255, 255, 255, 0.08);
  --border-card: rgba(255, 255, 255, 0.1);
  --border-card-hover: rgba(255, 255, 255, 0.25);

  --cyan: #600000;
  --purple: #7a5200;
  --magenta: #3d0000;
  --gold: #5c3f00;

  --gradient-primary: linear-gradient(135deg, var(--cyan), var(--purple));
  --gradient-accent: linear-gradient(135deg, var(--purple), var(--magenta));
  --gradient-warm: linear-gradient(135deg, var(--magenta), var(--gold));

  --text-primary: #f0f0f5;
  --text-muted: rgba(240, 240, 245, 0.5);

  --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --radius: 20px;
  --transition: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

html,
body {
  height: 100%;
  font-family: var(--font);
  background: var(--bg-dark);
  color: var(--text-primary);
  overflow: hidden;
  -webkit-font-smoothing: antialiased;
}

/* --- Particle Canvas --- */
#particles {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
}

/* ========================================
   Start Overlay
   ======================================== */
#start-overlay {
  position: fixed;
  inset: 0;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  background: radial-gradient(ellipse at center, rgba(10, 10, 18, 0.85), var(--bg-dark));
  backdrop-filter: blur(6px);
  transition: opacity 0.6s ease, visibility 0.6s ease;
}

#start-overlay.hidden {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.start-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 24px;
  position: relative;
}

#start-btn {
  position: relative;
  z-index: 2;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  border: 2px solid rgba(255, 255, 255, 0.15);
  background: rgba(255, 255, 255, 0.05);
  color: var(--cyan);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
}

#start-btn:hover {
  background: rgba(0, 229, 255, 0.12);
  border-color: var(--cyan);
  transform: scale(1.08);
  box-shadow: 0 0 40px rgba(0, 229, 255, 0.3);
}

#start-btn svg {
  margin-left: 4px;
}

.pulse-ring {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 100px;
  height: 100px;
  transform: translate(-50%, -50%);
  border: 2px solid var(--cyan);
  border-radius: 50%;
  animation: pulse 2s ease-out infinite;
  z-index: 1;
}

@keyframes pulse {
  0% {
    transform: translate(-50%, -50%) scale(1);
    opacity: 0.6;
  }

  100% {
    transform: translate(-50%, -50%) scale(2.2);
    opacity: 0;
  }
}

.start-text {
  font-size: 0.95rem;
  font-weight: 300;
  letter-spacing: 3px;
  text-transform: uppercase;
  color: var(--text-muted);
  animation: textFade 2s ease-in-out infinite alternate;
}

@keyframes textFade {
  0% {
    opacity: 0.4;
  }

  100% {
    opacity: 0.8;
  }
}

.start-hint {
  font-size: 0.7rem;
  font-weight: 300;
  letter-spacing: 1.5px;
  color: rgba(240, 240, 245, 0.3);
  margin-top: -16px;
}

.mute-toggle-btn {
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-radius: 50%;
  width: 34px;
  height: 34px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  cursor: pointer;
  transition: var(--transition);
  margin-top: -12px;
}

.mute-toggle-btn:hover {
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-primary);
  border-color: rgba(255, 255, 255, 0.3);
  transform: scale(1.1);
  box-shadow: 0 0 15px rgba(255, 255, 255, 0.1);
}

/* ========================================
   Stage
   ======================================== */
#stage {
  position: relative;
  z-index: 1;
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  padding-top: 12vh;
  gap: 30px;
}

/* --- Words --- */
/* Both containers share the same visual slot so there's no layout jump */
.words-slot {
  position: relative;
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  min-height: 1px;
}

#words-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  transition: opacity 0.3s ease;
}

#words-container.fading {
  opacity: 0;
}

#words-container.hidden {
  opacity: 0;
  pointer-events: none;
  position: absolute;
}

#merged-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  opacity: 0;
  transition: opacity 0.8s ease;
}

#merged-container.visible {
  opacity: 1;
}

.word {
  display: flex;
  gap: 2px;
  font-weight: 800;
  font-size: clamp(2.2rem, 7vw, 5.5rem);
  letter-spacing: 4px;
}

.word .letter {
  display: inline-block;
  opacity: 0;
  transform: translateY(30px) scale(0.7);
  transition: opacity 0.4s ease, transform 0.4s ease, color 0.6s ease, text-shadow 0.6s ease;
}

.word .letter.visible {
  opacity: 1;
  transform: translateY(0) scale(1);
}

/* Technology letters color */
#word-technology .letter {
  color: var(--cyan);
  text-shadow: 0 0 20px rgba(0, 229, 255, 0.3);
}

/* Knowledge letters color */
#word-knowledge .letter {
  color: var(--purple);
  text-shadow: 0 0 20px rgba(178, 75, 243, 0.3);
}

/* Merged word */
.word.merged .letter {
  color: var(--text-primary);
}

.word.merged .letter.visible {
  animation: mergeGlow 1.2s ease forwards;
}

@keyframes mergeGlow {
  0% {
    opacity: 0;
    transform: translateY(20px) scale(0.5);
    text-shadow: none;
  }

  50% {
    text-shadow: 0 0 40px var(--cyan), 0 0 80px var(--purple);
  }

  100% {
    opacity: 1;
    transform: translateY(0) scale(1);
    text-shadow: 0 0 15px rgba(0, 229, 255, 0.4), 0 0 30px rgba(178, 75, 243, 0.2);
  }
}

/* Highlight letters from Tech */
.word.merged .letter.from-tech {
  color: var(--cyan);
}

/* Highlight letters from Knowledge */
.word.merged .letter.from-know {
  color: var(--purple);
}

/* Tagline */
.tagline {
  font-size: clamp(0.85rem, 2vw, 1.15rem);
  font-weight: 300;
  letter-spacing: 5px;
  text-transform: uppercase;
  color: var(--text-muted);
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 0.8s ease 0.6s, transform 0.8s ease 0.6s;
}

#merged-container.visible .tagline {
  opacity: 1;
  transform: translateY(0);
}

/* ========================================
   Cards
   ======================================== */
#cards-container {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  width: min(90vw, 960px);
  margin-top: 30px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.6s ease;
  align-items: start;
}

#cards-container.visible {
  opacity: 1;
  pointer-events: auto;
}

/* Card group wraps a card + its sub-button */
.card-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
  transform: translateY(40px);
  opacity: 0;
  transition: transform 0.4s ease, opacity 0.4s ease;
}

.card-group.visible {
  transform: translateY(0);
  opacity: 1;
}

.card {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 32px 16px;
  border-radius: var(--radius);
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  backdrop-filter: blur(16px);
  text-decoration: none;
  color: var(--text-primary);
  cursor: pointer;
  transition: var(--transition);
  overflow: hidden;
}

/* Only standalone cards (not inside card-group) get their own entrance animation */
#cards-container>.card {
  transform: translateY(40px);
  opacity: 0;
}

#cards-container>.card.visible {
  transform: translateY(0);
  opacity: 1;
}

/* Cards inside groups are always visible once the group is visible */
.card-group .card {
  transform: none;
  opacity: 1;
}

.card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius);
  background: radial-gradient(circle at 50% 0%, rgba(0, 229, 255, 0.08), transparent 70%);
  opacity: 0;
  transition: opacity var(--transition);
}

.card:hover::before {
  opacity: 1;
}

.card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-card-hover);
  transform: translateY(-6px);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4), 0 0 30px rgba(0, 229, 255, 0.08);
}

/* Individual card accent colors on hover */
#card-explore:hover {
  border-color: var(--magenta);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4), 0 0 30px rgba(96, 0, 0, 0.25);
}

#card-explore:hover .card-icon {
  color: var(--magenta);
}

#card-learn:hover {
  border-color: var(--cyan);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4), 0 0 30px rgba(96, 0, 0, 0.25);
}

#card-learn:hover .card-icon {
  color: var(--cyan);
}

#card-play:hover {
  border-color: var(--purple);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4), 0 0 30px rgba(122, 82, 0, 0.25);
}

#card-play:hover .card-icon {
  color: var(--purple);
}

#card-create:hover {
  border-color: var(--gold);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4), 0 0 30px rgba(92, 63, 0, 0.25);
}

#card-create:hover .card-icon {
  color: var(--gold);
}

.card-icon {
  color: var(--text-muted);
  transition: color var(--transition), transform var(--transition);
}

.card:hover .card-icon {
  transform: scale(1.1);
}

.card-title {
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 1.5px;
  text-transform: uppercase;
}

.card-desc {
  font-size: 0.78rem;
  font-weight: 300;
  color: var(--text-muted);
  letter-spacing: 0.5px;
}

/* Sub-button (centered below each card) */
.sub-btn {
  display: block;
  width: 100%;
  text-align: center;
  padding: 14px 16px;
  border-radius: var(--radius);
  border: 1px solid var(--border-card);
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  color: var(--text-primary);
  font-family: var(--font);
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  cursor: pointer;
  transition: var(--transition);
}

.sub-btn:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-card-hover);
  color: var(--text-primary);
  transform: translateY(-3px);
  box-shadow: 0 12px 36px rgba(0, 0, 0, 0.4), 0 0 20px rgba(96, 0, 0, 0.12);
}

/* ========================================
   Responsive
   ======================================== */

/* Laptop / Small desktop */
@media (max-width: 1024px) {
  #cards-container {
    width: min(94vw, 800px);
    gap: 16px;
  }

  .card {
    padding: 26px 14px;
  }
}

/* Tablet */
@media (max-width: 768px) {

  html,
  body {
    overflow-y: auto;
  }

  #stage {
    min-height: 100vh;
    height: auto;
    padding: 40px 0;
  }

  #cards-container {
    grid-template-columns: repeat(2, 1fr);
    gap: 14px;
    width: 90vw;
  }

  .card {
    padding: 24px 12px;
  }

  .word {
    letter-spacing: 2px;
  }

  .sub-btn {
    font-size: 0.7rem;
    padding: 8px 10px;
  }
}

/* Mobile */
@media (max-width: 480px) {
  #cards-container {
    grid-template-columns: 1fr 1fr;
    gap: 10px;
    width: 94vw;
  }

  .word {
    font-size: clamp(1.6rem, 8vw, 2.5rem);
    letter-spacing: 1px;
  }

  .card {
    padding: 20px 10px;
    gap: 8px;
  }

  .card-title {
    font-size: 0.95rem;
  }

  .card-icon svg {
    width: 28px;
    height: 28px;
  }

  .tagline {
    letter-spacing: 2px;
    font-size: 0.7rem;
  }

  #start-btn {
    width: 80px;
    height: 80px;
  }

  .pulse-ring {
    width: 80px;
    height: 80px;
  }
}

/* Very small screens */
@media (max-width: 360px) {
  #cards-container {
    grid-template-columns: 1fr;
  }
}