/* ── Ocean Pixel Theme ── */

@import url('https://fonts.googleapis.com/css2?family=Press+Start+2P&family=Noto+Sans+SC:wght@400;500;700&family=JetBrains+Mono:wght@400;500&display=swap');

:root {
  --ocean-deep: #1a3a4a;
  --ocean-mid: #2a6b7c;
  --ocean-light: #5bb5c5;
  --ocean-foam: #b8e8ef;
  --ocean-mist: #e8f6f8;
  --sand: #f5e6c8;
  --sand-light: #faf3e6;
  --coral: #e8836b;
  --coral-light: #f4a996;
  --seaweed: #5ba67a;
  --seaweed-light: #8fcca5;
  --shell: #d4a574;
  --white: #fefefe;
  --panel: #fefefe;
  --text: #2c3e50;
  --text-light: #5a6c7d;
  --pixel-border: 3px solid var(--ocean-mid);
  --pixel-shadow: 4px 4px 0 var(--ocean-deep);
  --sidebar-w: 68px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: 'Noto Sans SC', sans-serif;
  color: var(--text);
  background: var(--ocean-mist);
  line-height: 1.7;
  position: relative;
  overflow: hidden;
  height: 100vh;
  cursor: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='11' height='17'%3E%3Cpath d='M1 1v12l3-3 3 5 2-2-3-4h4z' fill='%235bb5c5' stroke='%231a3a4a' stroke-width='.7'/%3E%3C/svg%3E") 1 1, auto;
}

/* ── Scroll-Snap Container ── */

.snap-container {
  position: absolute;
  top: 0;
  left: var(--sidebar-w);
  right: 0;
  bottom: 0;
  overflow-y: auto;
  overflow-x: hidden;
  scroll-snap-type: y mandatory;
  scroll-behavior: smooth;
}

.snap-section {
  min-height: 100vh;
  scroll-snap-align: start;
  display: flex;
  flex-direction: column;
  position: relative;
  z-index: 1;
}

.snap-footer {
  min-height: auto;
  height: auto;
  scroll-snap-align: end;
}

/* ── Sidebar Navigation ── */

.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-w);
  height: 100vh;
  background: var(--ocean-deep);
  border-right: 3px solid var(--ocean-mid);
  display: flex;
  flex-direction: column;
  z-index: 5000;
  overflow: hidden;
}

.sidebar-nav {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding-top: 8px;
}

.sidebar-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: 10px 4px 8px;
  text-decoration: none;
  color: var(--ocean-foam);
  border-left: 3px solid transparent;
  transition: background 0.15s, border-color 0.15s, transform 0.15s;
  position: relative;
}

.sidebar-item:hover {
  background: rgba(91, 181, 197, 0.15);
  color: var(--ocean-light);
  text-decoration: none;
  transform: translateX(2px);
}

.sidebar-item.active {
  border-left-color: var(--coral);
  background: rgba(91, 181, 197, 0.1);
  color: var(--white);
}

.sidebar-item.active .sidebar-icon {
  color: var(--coral);
  text-shadow: 0 0 6px rgba(232, 131, 107, 0.4);
}

.sidebar-icon {
  font-family: 'Press Start 2P', monospace;
  font-size: 14px;
  line-height: 1;
  display: block;
  color: var(--ocean-light);
  transition: color 0.15s;
}

.sidebar-label {
  font-family: 'Press Start 2P', monospace;
  font-size: 7px;
  line-height: 1;
  letter-spacing: 0.5px;
  white-space: nowrap;
  opacity: 0.8;
}

.sidebar-controls {
  border-top: 2px solid var(--ocean-mid);
  padding: 6px 0;
  display: flex;
  flex-direction: column;
}

.sidebar-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: 8px 4px;
  background: none;
  border: none;
  color: var(--ocean-foam);
  cursor: pointer;
  font-family: inherit;
  transition: background 0.15s, color 0.15s, transform 0.15s;
}

.sidebar-btn:hover {
  background: rgba(91, 181, 197, 0.15);
  color: var(--ocean-light);
  transform: translateX(2px);
}

.sidebar-btn .sidebar-icon {
  font-size: 14px;
}

.sidebar-btn .sidebar-label {
  font-size: 7px;
}

.sidebar-btn.bgm-playing .sidebar-icon {
  color: var(--seaweed-light);
  text-shadow: 0 0 6px rgba(143, 204, 165, 0.4);
}

/* ── Pixel Wave Decorations ── */

.pixel-wave-top {
  height: 24px;
  background:
    linear-gradient(135deg, var(--ocean-light) 25%, transparent 25%) -12px 0,
    linear-gradient(225deg, var(--ocean-light) 25%, transparent 25%) -12px 0,
    linear-gradient(315deg, var(--ocean-light) 25%, transparent 25%),
    linear-gradient(45deg, var(--ocean-light) 25%, transparent 25%);
  background-size: 24px 24px;
  background-color: var(--ocean-mid);
  flex-shrink: 0;
}

.pixel-wave-bottom {
  height: 24px;
  background:
    linear-gradient(135deg, var(--ocean-mid) 25%, transparent 25%) -12px 0,
    linear-gradient(225deg, var(--ocean-mid) 25%, transparent 25%) -12px 0,
    linear-gradient(315deg, var(--ocean-mid) 25%, transparent 25%),
    linear-gradient(45deg, var(--ocean-mid) 25%, transparent 25%);
  background-size: 24px 24px;
  background-color: var(--ocean-deep);
  flex-shrink: 0;
}

/* ── Hero Section ── */

.hero-section {
  background: linear-gradient(180deg, var(--ocean-deep) 0%, var(--ocean-mid) 100%);
  color: var(--white);
  text-align: center;
  justify-content: center;
  align-items: center;
  position: relative;
}

.hero-section .pixel-wave-top {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
}

.hero-wave-bottom {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 8px;
  background: repeating-linear-gradient(
    90deg,
    var(--ocean-foam) 0 8px,
    var(--ocean-light) 8px 16px
  );
}

.hero-inner {
  z-index: 1;
}

.hero-inner h1 {
  font-family: 'Press Start 2P', monospace;
  font-size: 2.2rem;
  margin-bottom: 1rem;
  text-shadow: 3px 3px 0 rgba(0,0,0,0.3);
  letter-spacing: 3px;
}

.hero-inner .subtitle {
  font-size: 1.15rem;
  color: var(--ocean-foam);
  margin-bottom: 3rem;
  min-height: 1.5em;
}

.hero-scroll-hint {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0;
  opacity: 0.6;
}

.scroll-arrow {
  font-family: 'Press Start 2P', monospace;
  font-size: 12px;
  color: var(--ocean-foam);
  animation: bounce-arrow 1.5s ease-in-out infinite;
  line-height: 1.3;
}

.scroll-arrow:nth-child(2) { animation-delay: 0.15s; opacity: 0.7; }
.scroll-arrow:nth-child(3) { animation-delay: 0.3s; opacity: 0.4; }

@keyframes bounce-arrow {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(4px); }
}

/* ── Section Inner ── */

.section-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 2.5rem 2rem;
  flex: 1;
  width: 100%;
}

/* ── Image Footer & Reference Button ── */

.img-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 0.5rem;
}

.img-footer .caption {
  margin-top: 0;
}

.ref-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.4rem 0.9rem;
  background: var(--ocean-mid);
  color: var(--white);
  border: 2px solid var(--ocean-deep);
  box-shadow: 3px 3px 0 var(--ocean-deep);
  font-family: 'Press Start 2P', monospace;
  font-size: 0.6rem;
  cursor: pointer;
  transition: all 0.15s;
  letter-spacing: 0.5px;
  white-space: nowrap;
  flex-shrink: 0;
}

.ref-btn:hover {
  background: var(--ocean-light);
  color: var(--ocean-deep);
  transform: translate(-1px, -1px);
  box-shadow: 4px 4px 0 var(--ocean-deep);
  text-decoration: none;
}

/* ── Reference Panel (Detail Overlay) ── */

.ref-panel {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 7500;
  background: rgba(10, 20, 30, 0.92);
  align-items: center;
  justify-content: center;
  padding: 2rem;
}

.ref-panel.open {
  display: flex;
}

.ref-panel-inner {
  position: relative;
  max-width: 800px;
  width: 90%;
  max-height: 85vh;
  overflow-y: auto;
  background: var(--panel);
  border: var(--pixel-border);
  box-shadow: 0 0 40px rgba(91, 181, 197, 0.1);
  padding: 2rem;
}

.ref-panel-inner > h3:first-child {
  margin-top: 0;
  margin-bottom: 1rem;
}

.ref-panel-close {
  position: absolute;
  top: 0.75rem;
  right: 0.75rem;
  background: none;
  border: 2px solid var(--ocean-mid);
  color: var(--ocean-mid);
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'Press Start 2P', monospace;
  font-size: 0.7rem;
  cursor: pointer;
  transition: all 0.15s;
}

.ref-panel-close:hover {
  background: var(--coral);
  border-color: var(--coral);
  color: var(--white);
}

/* ── Sections ── */

section h2 {
  font-family: 'Press Start 2P', monospace;
  font-size: 1.1rem;
  color: var(--ocean-deep);
  margin-bottom: 1.5rem;
  padding-bottom: 0.5rem;
  border-bottom: 4px solid var(--ocean-light);
  display: inline-block;
  letter-spacing: 1px;
}

h3 {
  font-size: 1.1rem;
  color: var(--ocean-mid);
  margin: 1rem 0 0.5rem;
}

h4 {
  font-size: 1rem;
  color: var(--ocean-deep);
  margin-bottom: 0.5rem;
}

/* ── Cards ── */

.card {
  background: var(--panel);
  border: var(--pixel-border);
  box-shadow: var(--pixel-shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

/* ── Images ── */

.img-full {
  width: 100%;
  height: auto;
  border: 2px solid var(--ocean-foam);
  margin: 1rem 0;
  image-rendering: auto;
}

.img-center {
  display: block;
  margin: 1rem auto;
  height: auto;
  border: 2px solid var(--ocean-foam);
}

.caption {
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-light);
  margin-top: 0.25rem;
}

/* ── Steps ── */

.steps {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.step {
  display: flex;
  gap: 1rem;
  background: var(--panel);
  border: var(--pixel-border);
  box-shadow: var(--pixel-shadow);
  padding: 1.25rem;
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.step-number {
  font-family: 'Press Start 2P', monospace;
  font-size: 1.5rem;
  color: var(--white);
  background: var(--ocean-mid);
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  box-shadow: 2px 2px 0 var(--ocean-deep);
}

.step-content { flex: 1; }
.step-content h3 { margin-top: 0; }

/* ── Code ── */

pre {
  background: var(--ocean-deep);
  color: var(--ocean-foam);
  padding: 1rem;
  overflow-x: auto;
  white-space: pre-wrap;
  overflow-wrap: break-word;
  border: 2px solid var(--ocean-mid);
  box-shadow: inset 0 2px 4px rgba(0,0,0,0.3);
  margin: 0.75rem 0;
}

code {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.85rem;
}

p code, li code, td code {
  background: var(--sand-light);
  color: var(--coral);
  padding: 0.15rem 0.4rem;
  border: 1px solid var(--sand);
  font-size: 0.85em;
}

/* ── Tables ── */

table {
  width: 100%;
  border-collapse: collapse;
  margin: 0.75rem 0;
}

th {
  background: var(--ocean-mid);
  color: var(--white);
  padding: 0.6rem 0.75rem;
  text-align: left;
  font-size: 0.85rem;
  font-weight: 500;
  border: 2px solid var(--ocean-deep);
}

td {
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--ocean-foam);
  font-size: 0.9rem;
}

tr:nth-child(even) { background: var(--ocean-mist); }
tr:hover { background: var(--sand-light); }

/* ── Grid ── */

.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

/* ── Badges ── */

.badge {
  font-size: 0.7rem;
  padding: 0.2rem 0.5rem;
  color: var(--white);
  margin-left: 0.5rem;
  vertical-align: middle;
}

.badge.blue { background: var(--ocean-mid); }
.badge.green { background: var(--seaweed); }

/* ── Tip Box ── */

.tip {
  background: var(--sand-light);
  border-left: 4px solid var(--shell);
  padding: 1rem 1.25rem;
  margin: 1.5rem 0;
  box-shadow: 2px 2px 0 var(--sand);
}

/* ── Lists ── */

ul {
  padding-left: 1.25rem;
  margin: 0.5rem 0;
}

li {
  margin: 0.3rem 0;
  font-size: 0.9rem;
}

li::marker {
  color: var(--ocean-light);
}

/* ── Links ── */

a {
  color: var(--ocean-mid);
  text-decoration: underline;
  text-decoration-color: var(--ocean-foam);
  text-underline-offset: 2px;
}

a:hover {
  color: var(--coral);
  text-decoration-color: var(--coral-light);
}

/* ── Footer ── */

footer {
  background: var(--ocean-deep);
  color: var(--ocean-foam);
  text-align: center;
  font-size: 0.85rem;
}

.footer-inner {
  padding: 1.5rem 0;
}

/* ── Loading Screen ── */

#loading-screen {
  position: fixed;
  inset: 0;
  z-index: 10000;
  background: #1a3a4a;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: opacity 0.6s ease;
}

#loading-screen.done {
  opacity: 0;
  pointer-events: none;
}

.loading-content {
  text-align: center;
  position: relative;
  z-index: 2;
}

.loading-title {
  font-family: 'Press Start 2P', monospace;
  font-size: 1.4rem;
  color: #b8e8ef;
  text-shadow: 3px 3px 0 rgba(0,0,0,0.3);
  margin-bottom: 2rem;
  letter-spacing: 2px;
}

.loading-bar {
  width: 260px;
  height: 20px;
  border: 3px solid #5bb5c5;
  background: rgba(0,0,0,0.3);
  margin: 0 auto 0.75rem;
  box-shadow: inset 0 2px 4px rgba(0,0,0,0.3);
}

.loading-fill {
  height: 100%;
  width: 0%;
  background: #5bb5c5;
  transition: width 0.4s steps(12);
}

.loading-percent {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.85rem;
  color: #5bb5c5;
}

.loading-ocean {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 0;
  background: #2a6b7c;
  transition: height 0.8s ease-out;
  z-index: 1;
  overflow: hidden;
}

.loading-wave {
  position: absolute;
  top: -12px;
  left: 0;
  right: 0;
  height: 12px;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='12' shape-rendering='crispEdges'%3E%3Cpolygon points='0,12 12,0 24,12' fill='%232a6b7c'/%3E%3C/svg%3E") repeat-x;
  animation: wave-drift 1.2s linear infinite;
}

@keyframes wave-drift {
  to { background-position: -24px 0; }
}

/* ── Scroll Progress ── */

.scroll-progress {
  position: fixed;
  top: 0;
  left: var(--sidebar-w);
  height: 4px;
  width: 0;
  background: var(--ocean-light);
  z-index: 9000;
  transition: width 0.15s linear;
}

/* ── Particles ── */

#particles {
  position: fixed;
  top: 0;
  left: var(--sidebar-w);
  right: 0;
  bottom: 0;
  z-index: 0;
  pointer-events: none;
}

.snap-section {
  z-index: 1;
}

/* ── Card & Step Hover ── */

.card:hover,
.step:hover {
  transform: translate(-2px, -4px);
  box-shadow: 6px 8px 0 var(--ocean-deep);
}

/* ── Fade-in Animations ── */

.fade-in {
  opacity: 0;
  transform: translateY(24px);
}

.fade-in.visible {
  animation: fadeInUp 0.6s ease forwards;
}

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

/* ── Dark Mode ── */

body.dark {
  --ocean-deep: #0c1a24;
  --ocean-mid: #1a4a5c;
  --ocean-foam: #80c8d8;
  --ocean-mist: #101e28;
  --sand: #2a3830;
  --sand-light: #1a2830;
  --panel: #152530;
  --text: #c8d8e0;
  --text-light: #708a98;
  --pixel-shadow: 4px 4px 0 rgba(0,0,0,0.5);
}

body.dark th,
body.dark .step-number,
body.dark .badge {
  color: #e0eaef;
}

body.dark .pixel-wave-top {
  background-color: var(--ocean-deep);
}

body.dark .hero-wave-bottom {
  background: repeating-linear-gradient(
    90deg,
    var(--ocean-mid) 0 8px,
    var(--ocean-deep) 8px 16px
  );
}

body.dark pre {
  box-shadow: inset 0 2px 6px rgba(0,0,0,0.5);
}

body.dark .sidebar {
  background: #080e14;
  border-right-color: var(--ocean-mid);
}

body.dark .mobile-nav {
  background: #080e14;
  border-top-color: var(--ocean-mid);
}

/* ── Lightbox ── */

.lightbox {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 8000;
  background: rgba(10, 20, 30, 0.92);
  align-items: center;
  justify-content: center;
  padding: 2rem;
  cursor: pointer;
}

.lightbox.active {
  display: flex;
}

.lightbox-body {
  max-width: 780px;
  width: 90%;
  max-height: 90vh;
  display: flex;
  flex-direction: column;
  cursor: default;
}

.lightbox-body img {
  width: 100%;
  height: auto;
  max-height: 55vh;
  object-fit: contain;
  border: 3px solid var(--ocean-light);
  box-shadow: 0 0 40px rgba(91, 181, 197, 0.15);
  display: block;
}

.lightbox-caption {
  background: var(--ocean-deep);
  border: 2px solid var(--ocean-mid);
  border-top: none;
  padding: 1rem 1.25rem;
  color: var(--ocean-foam);
  font-size: 0.9rem;
  line-height: 1.8;
  min-height: 3.5rem;
}

/* ── Typing Cursor ── */

.typing-cursor::after {
  content: '\25CC';
  color: var(--ocean-light);
  animation: cursor-blink 0.7s steps(2) infinite;
  margin-left: 2px;
}

@keyframes cursor-blink {
  50% { opacity: 0; }
}

/* ── Clickable Images ── */

.img-full, .img-center {
  cursor: pointer;
  transition: box-shadow 0.25s ease;
}

.img-full:hover, .img-center:hover {
  box-shadow: 0 0 15px rgba(91, 181, 197, 0.3);
}

/* ── Mobile Bottom Navigation ── */

.mobile-nav {
  display: none;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: 52px;
  background: var(--ocean-deep);
  border-top: 3px solid var(--ocean-mid);
  z-index: 5000;
  align-items: center;
  justify-content: space-around;
  padding: 0 4px;
}

.mobile-nav-item {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  font-family: 'Press Start 2P', monospace;
  font-size: 12px;
  color: var(--ocean-foam);
  text-decoration: none;
  background: none;
  border: none;
  cursor: pointer;
  transition: color 0.15s, background 0.15s;
  border-radius: 0;
}

.mobile-nav-item:hover,
.mobile-nav-item:active {
  background: rgba(91, 181, 197, 0.15);
  color: var(--ocean-light);
  text-decoration: none;
}

.mobile-nav-item.active {
  color: var(--coral);
  text-shadow: 0 0 6px rgba(232, 131, 107, 0.4);
}

.mobile-nav-item.bgm-playing {
  color: var(--seaweed-light);
  text-shadow: 0 0 6px rgba(143, 204, 165, 0.4);
}

/* ── Responsive ── */

@media (max-width: 768px) {
  :root {
    --sidebar-w: 0px;
  }

  .sidebar {
    display: none;
  }

  .mobile-nav {
    display: flex;
  }

  .snap-container {
    left: 0;
    bottom: 52px;
  }

  .scroll-progress {
    left: 0;
  }

  #particles {
    left: 0;
  }

  .hero-inner h1 { font-size: 1.4rem; }
  .hero-inner .subtitle { font-size: 0.95rem; }
  .grid-2 { grid-template-columns: 1fr; }
  .step { flex-direction: column; }
  .step-number { width: 36px; height: 36px; font-size: 1.1rem; }
  .section-inner { padding: 1.5rem 1rem; }
}

/* ── Reduced Motion ── */

@media (prefers-reduced-motion: reduce) {
  .snap-container { scroll-snap-type: none; scroll-behavior: auto; }
  .fade-in { opacity: 1; transform: none; }
  .fade-in.visible { animation: none; }
  #particles { display: none; }
  .loading-wave { animation: none; }
  #loading-screen { transition-duration: 0.01s; }
  .card, .step { transition: none; }
  .typing-cursor::after { animation: none; }
  .img-full, .img-center { transition: none; }
  .scroll-arrow { animation: none; }
  .sidebar-item, .sidebar-btn { transition: none; }
}