/* ================================================================
   UniCheatSheet – Lecture Notes Page
   Modern Premium Dark Theme with Cyan Accents
   ================================================================ */

/* ---------- Design Tokens ---------- */
:root {
  --header-height: 70px;
  --accent: #00e5ff;
  --accent-dim: rgba(0, 229, 255, 0.15);
  --accent-glow: rgba(0, 229, 255, 0.35);
  --surface: rgba(255, 255, 255, 0.06);
  --surface-hover: rgba(255, 255, 255, 0.12);
  --border: rgba(255, 255, 255, 0.1);
  --border-hover: rgba(0, 229, 255, 0.4);
  --text-primary: #ffffff;
  --text-secondary: rgba(255, 255, 255, 0.7);
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --transition-fast: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ---------- Base Styles ---------- */
body {
  background-color: #000;
  background-image: linear-gradient(160deg, rgba(0, 10, 20, 0.92), rgba(0, 0, 0, 0.88)),
    url('https://ik.imagekit.io/zkkuwm5z9/Basics/lecture-image.webp');
  background-size: cover;
  background-attachment: fixed;
  color: var(--text-primary);
  font-family: 'Inter', 'Montserrat', system-ui, -apple-system, sans-serif;
  line-height: 1.6;
  padding-top: 70px;
}

/* Ambient floating particles */
body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-image:
    radial-gradient(2px 2px at 20% 30%, rgba(0, 229, 255, 0.15) 0%, transparent 100%),
    radial-gradient(2px 2px at 40% 70%, rgba(0, 229, 255, 0.1) 0%, transparent 100%),
    radial-gradient(1px 1px at 70% 20%, rgba(255, 255, 255, 0.08) 0%, transparent 100%),
    radial-gradient(1px 1px at 90% 60%, rgba(0, 229, 255, 0.08) 0%, transparent 100%),
    radial-gradient(2px 2px at 10% 80%, rgba(255, 255, 255, 0.05) 0%, transparent 100%),
    radial-gradient(1px 1px at 60% 50%, rgba(0, 229, 255, 0.06) 0%, transparent 100%);
  pointer-events: none;
  z-index: 0;
  animation: particleDrift 20s ease-in-out infinite alternate;
}

@keyframes particleDrift {
  0% {
    transform: translateY(0) translateX(0);
  }

  50% {
    transform: translateY(-15px) translateX(10px);
  }

  100% {
    transform: translateY(5px) translateX(-8px);
  }
}

/* ---------- Header Wrapper ---------- */
.header-wrapper {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 22vh;
  width: 100%;
  position: relative;
  z-index: 1;
}

/* ---------- Page Title ---------- */
.lecture-notes-title {
  font-size: 4rem;
  padding: 20px;
  font-family: 'Inter', 'Montserrat', system-ui, sans-serif;
  color: var(--text-primary);
  text-align: center;
  font-weight: 800;
  letter-spacing: 6px;
  text-transform: uppercase;
  text-shadow: 0 0 30px rgba(0, 229, 255, 0.2);
  position: relative;
  margin-bottom: 20px;
  animation: titleReveal 0.8s ease-out both;
}

@keyframes titleReveal {
  from {
    opacity: 0;
    transform: translateY(-25px);
    letter-spacing: 20px;
  }

  to {
    opacity: 1;
    transform: translateY(0);
    letter-spacing: 6px;
  }
}

.lecture-notes-title::after {
  content: '';
  position: absolute;
  left: 50%;
  bottom: 0;
  transform: translateX(-50%);
  width: 0;
  height: 3px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
  animation: underlineAnimation 1.2s ease-out 0.4s forwards;
  border-radius: 2px;
}

@keyframes underlineAnimation {
  from {
    width: 0;
    opacity: 0;
  }

  to {
    width: 550px;
    opacity: 1;
  }
}

/* ---------- Semester Subtitle ---------- */
.lect-sem {
  font-size: 2.4rem;
  color: var(--accent);
  text-align: center;
  font-weight: 300;
  letter-spacing: 4px;
  font-family: 'Inter', 'Montserrat', system-ui, sans-serif;
  text-shadow: 0 0 20px rgba(0, 229, 255, 0.15);
  position: relative;
  padding-bottom: 15px;
  animation: subtitleReveal 0.8s ease-out 0.3s both;
}

@keyframes subtitleReveal {
  from {
    opacity: 0;
    transform: translateY(15px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.lect-sem::after {
  content: '';
  position: absolute;
  left: 50%;
  bottom: 0;
  transform: translateX(-50%);
  width: 80px;
  height: 2px;
  background: var(--accent);
  border-radius: 1px;
  box-shadow: 0 0 12px var(--accent-glow);
}

/* ---------- Content Slider Area ---------- */
.content-slider {
  margin: 60px auto;
  width: 92%;
  max-width: 1400px;
  position: relative;
  z-index: 1;
}

/* ---------- Section Headings ---------- */
.content-slider h2 {
  font-size: 1.8rem;
  font-family: 'Inter', 'Montserrat', system-ui, sans-serif;
  color: var(--text-primary);
  margin: 70px 0 25px 0;
  padding: 12px 20px;
  border-left: 3px solid var(--accent);
  text-transform: uppercase;
  letter-spacing: 2px;
  font-weight: 600;
  position: relative;
  background: linear-gradient(90deg, var(--accent-dim), transparent 70%);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.content-slider h2:not(:first-child)::before {
  content: '';
  position: absolute;
  top: -35px;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(to right,
      transparent,
      rgba(0, 229, 255, 0.2),
      transparent);
}

/* ---------- Slider Container ---------- */
.slider-container {
  background: var(--surface);
  border-radius: var(--radius-lg);
  padding: 28px;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border);
  position: relative;
  overflow: hidden;
  margin-bottom: 50px;
  transition: border-color var(--transition-smooth);
}

.slider-container::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--accent-glow), transparent);
  opacity: 0;
  transition: opacity var(--transition-smooth);
}

.slider-container:hover {
  border-color: var(--border-hover);
}

.slider-container:hover::before {
  opacity: 1;
}

/* ---------- Slider ---------- */
.slider {
  display: flex;
  gap: 22px;
  padding: 10px 5px;
  overflow-x: auto;
  scroll-behavior: smooth;
  -ms-overflow-style: none;
  scrollbar-width: none;
  scroll-snap-type: x proximity;
}

.slider::-webkit-scrollbar {
  display: none;
}

/* ---------- Slide Cards ---------- */
.slide {
  flex: 0 0 265px;
  height: 275px;
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.4);
  background: var(--surface);
  border: 1px solid var(--border);
  transition: all var(--transition-smooth);
  position: relative;
  display: flex;
  flex-direction: column;
  cursor: pointer;
  scroll-snap-align: start;
}

.slide::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius-md);
  padding: 1px;
  background: linear-gradient(135deg, rgba(0, 229, 255, 0.3), transparent 50%, rgba(0, 229, 255, 0.1));
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  opacity: 0;
  transition: opacity var(--transition-smooth);
  z-index: 2;
  pointer-events: none;
}

.slide img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  flex: 1;
  transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1), filter var(--transition-smooth);
}

.slide:hover {
  transform: translateY(-8px) scale(1.02);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.5), 0 0 30px rgba(0, 229, 255, 0.08);
  border-color: var(--border-hover);
}

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

.slide:hover img {
  transform: scale(1.08);
  filter: brightness(1.1);
}

/* ---------- Hover Text Label ---------- */
.hover-text {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  color: var(--text-primary);
  padding: 14px 12px;
  font-size: 0.95rem;
  font-weight: 600;
  text-align: center;
  letter-spacing: 0.5px;
  background: linear-gradient(to top, rgba(0, 0, 0, 0.85) 0%, rgba(0, 0, 0, 0.4) 70%, transparent 100%);
  transition: all var(--transition-smooth);
  z-index: 3;
}

.slide:hover .hover-text {
  padding-bottom: 18px;
  background: linear-gradient(to top, rgba(0, 15, 25, 0.92) 0%, rgba(0, 10, 20, 0.5) 80%, transparent 100%);
  text-shadow: 0 0 8px rgba(0, 229, 255, 0.3);
}

/* ---------- Slider Nav Buttons ---------- */
.slider-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 44px;
  height: 44px;
  background: rgba(0, 0, 0, 0.5);
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: var(--text-primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: 1.2rem;
  z-index: 10;
  backdrop-filter: blur(8px);
}

.slider-btn:hover {
  background: var(--accent-dim);
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-50%) scale(1.1);
  box-shadow: 0 0 15px rgba(0, 229, 255, 0.2);
}

.slider-btn.left {
  left: 8px;
}

.slider-btn.right {
  right: 8px;
}

/* ---------- Warning Section ---------- */
.warning {
  background: var(--surface);
  border-radius: var(--radius-lg);
  padding: 25px 40px;
  margin: 60px auto;
  max-width: 900px;
  text-align: center;
  border: 1px solid var(--border);
  backdrop-filter: blur(12px);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
  position: relative;
  overflow: hidden;
  z-index: 1;
}

.warning::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
}

.warning span {
  color: var(--text-secondary);
  font-size: 1.05rem;
  line-height: 1.8;
  font-weight: 400;
  display: block;
  letter-spacing: 0.3px;
  font-style: italic;
}

/* ---------- Footer ---------- */
.footer {
  padding: 30px 20px;
  margin-top: 50px;
  text-align: center;
  border-top: 1px solid var(--border);
  backdrop-filter: blur(10px);
  position: relative;
  z-index: 1;
}

.footer::before {
  content: '';
  position: absolute;
  top: 0;
  left: 20%;
  right: 20%;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--accent-glow), transparent);
}

.footer h3 {
  color: var(--text-primary);
  font-size: 1.5rem;
  margin-bottom: 10px;
  font-family: 'Inter', 'Montserrat', system-ui, sans-serif;
  letter-spacing: 2px;
  font-weight: 600;
}

.footer p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-top: 8px;
  font-family: 'Inter', 'Montserrat', system-ui, sans-serif;
}

/* ---------- Utility ---------- */
a {
  text-decoration: none;
  color: inherit;
}

a:hover {
  text-decoration: none;
  color: inherit;
}

/* ---------- Scroll Reveal Animation ---------- */
.content-slider section {
  opacity: 0;
  transform: translateY(30px);
  animation: sectionReveal 0.6s ease-out forwards;
}

.content-slider section:nth-child(1) {
  animation-delay: 0.1s;
}

.content-slider section:nth-child(2) {
  animation-delay: 0.2s;
}

.content-slider section:nth-child(3) {
  animation-delay: 0.3s;
}

.content-slider section:nth-child(4) {
  animation-delay: 0.4s;
}

.content-slider section:nth-child(5) {
  animation-delay: 0.5s;
}

.content-slider section:nth-child(6) {
  animation-delay: 0.6s;
}

.content-slider section:nth-child(7) {
  animation-delay: 0.7s;
}

@keyframes sectionReveal {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ---------- Layout Overrides ---------- */
.header-container {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background-color: rgba(0, 0, 0, 0.9);
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 20px;
  z-index: 100;
}

.menu {
  background-color: rgba(0, 0, 0, 0.9);
  z-index: 100;
  position: fixed;
  width: 100%;
  top: 0;
}

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.logo {
  height: 0;
}

h1 {
  font-size: clamp(2rem, 5vw, 4rem);
  line-height: 1.2;
}

h2 {
  font-size: clamp(1.5rem, 3vw, 2.5rem);
}

.slider-container {
  width: 100%;
  overflow: hidden;
}

.slider-item {
  flex: 0 0 auto;
  width: calc(100% - 40px);
  scroll-snap-align: start;
}

img {
  max-width: 100%;
  height: auto;
}

.slider-btn {
  min-width: 44px;
  min-height: 44px;
}

a,
button {
  min-height: 44px;
  padding: 10px;
  display: inline-flex;
  align-items: center;
}

/* ============================================
   RESPONSIVE BREAKPOINTS
   ============================================ */

/* Large tablets */
@media screen and (max-width: 1024px) {
  @keyframes underlineAnimation {
    from {
      width: 0;
    }

    to {
      width: 500px;
    }
  }

  .lecture-notes-title {
    font-size: 3.6rem;
  }

  .lect-sem {
    font-size: 2.2rem;
  }

  .slider-item {
    width: calc(50% - 40px);
  }
}

/* Tablets */
@media screen and (max-width: 768px) {
  @keyframes underlineAnimation {
    from {
      width: 0;
    }

    to {
      width: 300px;
    }
  }

  .lecture-notes-title {
    font-size: 3rem;
    letter-spacing: 4px;
  }

  .lect-sem {
    font-size: 2rem;
  }

  .slide {
    flex: 0 0 240px;
    height: 240px;
  }

  .slider {
    gap: 18px;
    padding: 8px;
  }

  .hover-text {
    padding: 12px;
    font-size: 0.9rem;
  }

  .menu {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: rgba(0, 0, 0, 0.95);
    padding: 20px;
    transform: translateX(-100%);
    transition: transform 0.3s ease;
  }

  .menu.active {
    transform: translateX(0);
  }

  .nav-items {
    flex-direction: column;
    gap: 15px;
  }
}

/* Narrow tablets */
@media screen and (max-width: 540px) {
  .content-slider h2 {
    font-size: 1.4rem !important;
    margin: 20px 0 10px 0;
    padding: 10px 15px;
  }

  .lecture-notes-title {
    font-size: 2.6rem;
    letter-spacing: 3px;
    margin-top: 20px;
    padding-bottom: 5px;
  }

  .content-slider {
    margin: 30px auto;
  }
}

/* Large Mobile */
@media screen and (max-width: 576px) {
  .slide {
    flex: 0 0 220px;
    height: 220px;
  }

  .slider {
    gap: 15px;
    padding: 6px;
  }

  .hover-text {
    padding: 10px;
    font-size: 0.88rem;
  }
}

/* Mobile Portrait */
@media screen and (max-width: 480px) {
  :root {
    --header-height: 60px;
  }

  @keyframes underlineAnimation {
    from {
      width: 0;
    }

    to {
      width: 225px;
    }
  }

  .lecture-notes-title {
    font-size: 2.2rem;
    letter-spacing: 2px;
  }

  .lect-sem {
    font-size: 1.6rem;
    letter-spacing: 3px;
  }

  .lect-sem::after {
    width: 60px;
  }

  .slide {
    flex: 0 0 200px;
    height: 200px;
  }

  .slider {
    gap: 12px;
    padding: 5px;
  }

  .hover-text {
    padding: 8px;
    font-size: 0.85rem;
  }

  .container {
    padding: 0 15px;
  }

  .logo {
    height: 30px;
  }
}

/* Small Mobile */
@media screen and (max-width: 320px) {
  @keyframes underlineAnimation {
    from {
      width: 0;
    }

    to {
      width: 200px;
    }
  }

  .slide {
    flex: 0 0 180px;
    height: 180px;
  }

  .slider {
    gap: 10px;
    padding: 4px;
  }

  .hover-text {
    padding: 6px;
    font-size: 0.82rem;
  }
}

@media (max-height: 600px) {
  .header-wrapper {
    min-height: 400px;
  }
}

@media screen and (min-width: 768px) {
  .slider-item {
    width: calc(50% - 40px);
  }
}

@media screen and (min-width: 1024px) {
  .slider-item {
    width: calc(33.333% - 40px);
  }
}

/* Large desktop */
@media screen and (min-width: 1200px) {
  .lecture-notes-title {
    font-size: 4.5rem;
  }

  .lect-sem {
    font-size: 2.6rem;
  }

  .content-slider h2 {
    font-size: 2rem;
  }

  .slide {
    flex: 0 0 280px;
    height: 290px;
  }

  .hover-text {
    font-size: 1rem;
  }
}