:root {
  --bg-color: #f6f7ff;
  --text-color: #333333;
  --title-color: #181b29;
  --overlay-text-color: rgba(0,0,0,0.05);
  --shelf-bg: linear-gradient(to bottom, #f0f0f0, #e0e0e0);
  --shelf-edge-top: rgba(255,255,255,0.01);
  --shelf-edge-bottom: rgba(0,0,0,0.1);
  --book-back-cover: #111111;
  --book-page: #ffffff;
  --book-page-border: rgba(0,0,0,0.2);
  --book-shadow: rgba(0,0,0,0.15);
  --book-shadow-strong: rgba(0,0,0,0.35);
  --side-book-bg: linear-gradient(to right, #444 0%, #666 50%, #444 100%);
  --side-book-text: #f0f0f0;
  --side-book-decoration: rgba(255,255,255,0.3);
  --toggle-dot: #333333;
}

/* ========== DOTTED GRID BACKGROUND ========== */
body {
  background-color: var(--bg-color);
  background-image: url("data:image/svg+xml,%3Csvg width='30' height='30' viewBox='0 0 30 30' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Ccircle cx='2' cy='2' r='1' fill='rgba(0,0,0,0.10)'/%3E%3C/svg%3E");
  margin: 0;
  padding: 0;
  min-height: 100vh;
  font-family: "Cabinet Grotesk", sans-serif;
  letter-spacing: -0.02em;
  color: var(--text-color);
  transition: background-color 0.5s ease, color 0.5s ease;
}

/* ========== BOOK TITLE OVERLAY (WATERMARK) ========== */
.book-title-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 0;
  opacity: 1;
  transition: opacity 0.3s ease;
  pointer-events: none;
}
.book-title-text {
  font-family: "Cabinet Grotesk", sans-serif;
  font-weight: 800;
  font-size: 14vw;
  color: var(--overlay-text-color);
  text-transform: uppercase;
  text-align: center;
  line-height: 1;
  max-width: 90vw;
  transition: color 0.5s ease;
}

/* ========== THEME TOGGLE DOT ========== */
.theme-toggle {
  position: fixed;
  top: 0px;
  right: 20px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--toggle-dot);
  cursor: pointer;
  z-index: 100;
  transition: background-color 0.3s ease;
}

/* ========== SHELF AND BOOKS ========== */
.shelf-container {
  position: relative;
  width: 100%;
  max-width: 1000px;
  height: 500px;
  margin: 0 auto 2rem auto;
  display: block;
  z-index: 1;
}
.shelf {
  display: block;
  position: absolute;
  bottom: 270px;
  left: 50%;
  transform: translateX(-50%);
  width: 80%;
  max-width: 800px;
  height: 15px;
  background: var(--shelf-bg);
  border-radius: 1px;
  z-index: 20;
  box-shadow:
    0px -1px 1px rgba(255,255,255,0.15),
    0px 2px 3px rgba(0,0,0,0.12),
    0px 5px 10px rgba(0,0,0,0.08),
    0px 15px 20px rgba(0,0,0,0.06),
    0px 25px 30px rgba(0,0,0,0.04),
    0px 40px 60px rgba(0,0,0,0.2),
    0px 60px 80px rgba(0,0,0,0.12);
  transition: background 0.5s ease, box-shadow 0.5s ease;
}
.shelf:after {
  content: "";
  position: absolute;
  bottom: -1px;
  left: 0;
  width: 100%;
  height: 1px;
  background-color: var(--shelf-edge-bottom);
  transition: background-color 0.5s ease;
}
.shelf:before {
  content: "";
  position: absolute;
  top: -2px;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--shelf-edge-top);
  transition: background-color 0.5s ease;
}
.books-wrapper {
  position: absolute;
  bottom: 287px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  justify-content: center;
  align-items: flex-end;
  gap: 2rem;
  z-index: 10;
}
.books__item {
  text-align: center;
  cursor: default;
  height: 220px;
}
.books__container {
  position: relative;
  width: 160px;
  margin: 0 auto;
  height: 100%;
}
.books__cover {
  position: relative;
  will-change: transform;
  height: 100%;
}
.books__hitbox {
  position: absolute;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  z-index: 10;
  cursor: pointer;
}
.books__back-cover {
  position: absolute;
  width: 96%;
  height: 96%;
  top: 2%;
  left: 2%;
  background: var(--book-back-cover);
  border-radius: 0 6px 6px 0;
  box-shadow: 2px 2px 5px rgba(0,0,0,0.25);
  z-index: -10;
  transition: background 0.5s ease;
}
.books__inside {
  position: absolute;
  width: 90%;
  height: 94%;
  top: 3%;
  left: 5%;
  z-index: 0;
}
.books__page {
  position: absolute;
  top: 0;
  right: 0;
  width: 98%;
  height: 100%;
  background: var(--book-page);
  border: 1px solid var(--book-page-border);
  border-radius: 0 6px 6px 0;
  box-shadow: 0 1px 3px rgba(0,0,0,0.15);
  transform-origin: right center;
  z-index: -5;
  transition: background 0.5s ease, border-color 0.5s ease;
}
.books__image {
  line-height: 0;
  position: relative;
  border-radius: 2px 6px 6px 2px;
  height: 100%;
  box-shadow: var(--book-shadow) 10px -5px 20px, var(--book-shadow) 20px 0px 30px;
  transform-origin: left center;
  cursor: pointer;
  will-change: transform, box-shadow;
  z-index: 10;
  transition: box-shadow 0.5s ease;
}
.books__image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 2px 6px 6px 2px;
}
.books__effect {
  position: absolute;
  width: 24px;
  height: 100%;
  margin-left: 12px;
  top: 0;
  border-left: 2px solid rgba(0,0,0,0.08);
  background-image: linear-gradient(
    90deg,
    rgba(255,255,255,0.25) 0%,
    rgba(255,255,255,0) 100%
  );
  transform-origin: left center;
  z-index: 5;
  pointer-events: none;
  will-change: margin-left;
}
.books__light {
  width: 100%;
  height: 100%;
  position: absolute;
  border-radius: 2px 6px 6px 2px;
  background-image: linear-gradient(
    90deg,
    rgba(255,255,255,0) 0%,
    rgba(255,255,255,0.5) 100%
  );
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  opacity: 0.15;
  transform-origin: left center;
  z-index: 4;
  pointer-events: none;
  mix-blend-mode: overlay;
  will-change: opacity;
}
.side-book {
  height: 220px;
  width: 30px;
  position: relative;
  cursor: pointer;
  background: var(--side-book-bg);
  border-radius: 2px;
  box-shadow: var(--book-shadow) 5px -3px 10px, var(--book-shadow) 10px 0px 15px;
  transform-origin: bottom center;
  will-change: transform, box-shadow;
  transition: background 0.5s ease, box-shadow 0.5s ease;
}
.side-book__title {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  writing-mode: vertical-rl;
  text-orientation: mixed;
  transform: rotate(180deg);
  color: var(--side-book-text);
  font-size: 12px;
  padding: 5px 0;
  text-align: center;
  text-transform: uppercase;
  letter-spacing: 1px;
  transition: color 0.5s ease;
}
.side-book__decoration {
  position: absolute;
  top: 20px;
  left: 50%;
  transform: translateX(-50%);
  width: 80%;
  height: 1px;
  background-color: var(--side-book-decoration);
  transition: background-color 0.5s ease;
}
.side-book__decoration:nth-child(2) {
  top: auto;
  bottom: 20px;
}
.book-shadow {
  position: absolute;
  bottom: 285px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  justify-content: center;
  align-items: flex-end;
  gap: 2rem;
  z-index: 15;
}
.book-shadow__item {
  width: 120px;
  height: 2px;
  background: radial-gradient(ellipse at center, var(--book-shadow) 0%, rgba(0,0,0,0) 70%);
  border-radius: 50%;
  will-change: width, opacity;
  transition: background 0.5s ease;
}
.book-shadow__item.side {
  width: 25px;
}

/* ========== BOOK DESCRIPTIONS ========== */
.book-descriptions {
  position: absolute;
  bottom: 30px;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: 640px;
  z-index: 5;
  height: 200px;
}
.book-description {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  opacity: 0;
  visibility: hidden;
  font-family: "Cabinet Grotesk", sans-serif;
  font-weight: 400;
  font-size: 1.1rem;
  line-height: 1.5;
  color: var(--text-color);
  transition: opacity 0.3s ease, visibility 0.3s ease, color 0.5s ease;
}
.book-description.active {
  opacity: 1;
  visibility: visible;
}
.book-description h3 {
  font-weight: 800;
  font-size: 1.8rem;
  margin-bottom: 0.5rem;
  color: var(--title-color);
  transition: color 0.5s ease;
}
.book-description .author {
  font-style: italic;
  opacity: 0.8;
  margin-bottom: 1rem;
}
.book-description p {
  margin-bottom: 0.75rem;
}



/* ========== RESPONSIVE ========== */
@media (max-width: 1100px) {
  .shelf-container {
    max-width: 98vw;
  }
  .books-wrapper {
    gap: 1rem;
  }
}
@media (max-width: 800px) {
  .book-title-text {
    font-size: 9vw;
  }
  .shelf-container {
    height: 380px;
  }
  .books__container, .books__item {
    width: 120px;
    height: 160px;
  }
  .side-book {
    height: 160px;
  }
  .book-shadow__item {
    width: 80px;
  }
}
@media (max-width: 600px) {
  .shelf-container {
    height: 290px;
  }
  .book-title-text {
    font-size: 7vw;
  }
  .books__container, .books__item {
    width: 80px;
    height: 100px;
  }
  .side-book {
    height: 100px;
    width: 18px;
  }
  .book-shadow__item {
    width: 40px;
  }
  .book-descriptions {
    font-size: 0.9rem;
    max-width: 95vw;
    height: 110px;
  }
}

/* ========== FONTS ========== */
@font-face {
  font-family: "Cabinet Grotesk";
  font-style: normal;
  font-weight: 800;
  src: local("Cabinet Grotesk"), url("https://fonts.cdnfonts.com/s/85514/CabinetGrotesk-Extrabold.woff") format("woff");
}
@font-face {
  font-family: "Cabinet Grotesk";
  font-style: normal;
  font-weight: 400;
  src: local("Cabinet Grotesk"), url("https://fonts.cdnfonts.com/s/85514/CabinetGrotesk-Medium.woff") format("woff");
}