:root {
  --bg: #e9edf2;
  --panel: #ffffff;
  --panel-2: #f2f5f8;
  --text: #1f2937;
  --muted: #5f6b78;
  --accent: #3b82f6;
  --border: #d4dce4;
  --shadow: 0 10px 25px rgba(0, 0, 0, 0.08);
  --radius: 18px;
}

:root[data-theme='dark'] {
  --bg: #0f1724;
  --panel: #172032;
  --panel-2: #111827;
  --text: #e5eef8;
  --muted: #9aa8b8;
  --accent: #60a5fa;
  --border: #2a3648;
  --shadow: 0 10px 25px rgba(0, 0, 0, 0.28);
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: Arial, Helvetica, sans-serif;
}

body {
  overflow-x: hidden;
  transition:
    background 0.25s ease,
    color 0.25s ease;
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  padding: 18px 5vw;
  background: rgba(255, 255, 255, 0.82);
  backdrop-filter: blur(4px);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
  transition:
    background 0.25s ease,
    border-color 0.25s ease;
}

:root[data-theme='dark'] .topbar {
  background: rgba(17, 24, 39, 0.82);
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-mark {
  width: 42px;
  height: 42px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--accent);
  font-size: 1.1rem;
}

.brand h1 {
  margin: 0;
  font-size: 1.15rem;
}

.brand p {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.tab-link {
  text-decoration: none;
  color: var(--text);
  background: var(--panel);
  border: 1px solid var(--border);
  padding: 10px 14px;
  border-radius: 999px;
  transition: 0.2s ease;
  font-size: 0.95rem;
}

.tab-link:hover,
.tab-link.active {
  border-color: var(--accent);
  color: var(--accent);
}

.theme-toggle {
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  border-radius: 999px;
  padding: 10px 14px;
  font-size: 0.95rem;
  cursor: pointer;
  transition: 0.2s ease;
}

.theme-toggle:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.page-shell {
  width: min(1100px, 92vw);
  margin: 0 auto;
  padding: 28px 0 60px;
}

.page-header {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

.eyebrow {
  display: inline-block;
  margin-bottom: 10px;
  color: var(--accent);
  font-size: 0.8rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.page-header h2 {
  margin: 0;
  font-size: clamp(1.8rem, 4vw, 3rem);
}

.page-header p {
  margin: 12px 0 0;
  color: var(--muted);
  line-height: 1.6;
}

.content-grid {
  margin-top: 22px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.simple-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
}

.simple-card h3 {
  margin-top: 0;
}

.simple-card p {
  color: var(--muted);
  line-height: 1.6;
}

.feature-box {
  margin-top: 24px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
}

.inventions-grid {
  margin-top: 22px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.invention-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}

.card-image {
  width: 100%;
  aspect-ratio: 16 / 10;
  display: block;
  object-fit: cover;
  background: #d9e1ea;
}

.card-body {
  padding: 18px;
}

.card-date {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 0.85rem;
  font-weight: bold;
}

.card-body h3 {
  margin: 0 0 10px;
  font-size: 1.2rem;
}

.card-body p {
  margin: 0;
  color: var(--muted);
  line-height: 1.6;
}

.timeline-scroll {
  position: relative;
  margin-top: 22px;
  display: flex;
  gap: 18px;
  overflow-x: auto;
  padding: 24px 8px 12px;
  scroll-snap-type: x mandatory;
}

.timeline-line {
  position: absolute;
  top: 58px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--border);
  z-index: 0;
}

.timeline-item {
  position: relative;
  min-width: 240px;
  flex: 0 0 auto;
  scroll-snap-align: start;
  z-index: 1;
}

.timeline-year {
  display: inline-block;
  margin-bottom: 12px;
  padding: 6px 10px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--accent);
  font-size: 0.85rem;
  font-weight: bold;
}

.timeline-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
}

.timeline-card h3 {
  margin: 0 0 8px;
  font-size: 1.1rem;
}

.timeline-card p {
  margin: 0;
  color: var(--muted);
  line-height: 1.6;
}

@media (max-width: 900px) {
  .topbar {
    flex-direction: column;
    align-items: stretch;
  }

  .tabs {
    justify-content: center;
  }

  .inventions-grid,
  .content-grid {
    grid-template-columns: 1fr;
  }
}

.theme-switch {
  position: relative;
  width: 46px;
  height: 24px;
  display: inline-block;
}

.theme-switch input {
  opacity: 0;
  width: 0;
  height: 0;
}

.slider {
  position: absolute;
  inset: 0;
  background: var(--border);
  border-radius: 999px;
  cursor: pointer;
  transition: 0.25s ease;
}

.slider::before {
  content: '';
  position: absolute;
  width: 18px;
  height: 18px;
  left: 3px;
  top: 3px;
  background: white;
  border-radius: 50%;
  transition: 0.25s ease;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
}

/* ON state */
.theme-switch input:checked + .slider {
  background: var(--accent);
}

.theme-switch input:checked + .slider::before {
  transform: translateX(22px);
}

/* Dark mode tweak */
:root[data-theme='dark'] .slider::before {
  background: #e5eef8;
}

.timeline-list {
  position: relative;
  max-width: 900px;
  margin: 3rem auto;
  padding: 2rem 1rem;
}

.timeline-list::before {
  content: '';
  position: absolute;
  top: 0;
  bottom: 0;
  left: 50%;
  width: 4px;
  transform: translateX(-50%);
  background: linear-gradient(
    to bottom,
    transparent,
    var(--accent),
    transparent
  );
  border-radius: 999px;
}

.timeline-item {
  position: relative;
  display: grid;
  grid-template-columns: 1fr 60px 1fr;
  align-items: center;
  margin: 2rem 0;
  min-height: 120px;
}

.timeline-item.left .timeline-content {
  grid-column: 1;
  justify-self: end;
  text-align: right;
}

.timeline-item.right .timeline-content {
  grid-column: 3;
  justify-self: start;
  text-align: left;
}

.timeline-dot {
  grid-column: 2;
  justify-self: center;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--panel);
  border: 4px solid var(--accent);
  box-shadow: 0 0 0 8px rgba(96, 165, 250, 0.15);
  z-index: 2;
}

.timeline-content {
  background: var(--panel);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 1rem 1.2rem;
  max-width: 320px;
  box-shadow: var(--shadow);
  transition: 0.25s ease;
}

.timeline-content:hover {
  transform: translateY(-3px);
  border-color: var(--accent);
}

.timeline-content h3 {
  margin: 0 0 0.4rem;
  font-size: 1.15rem;
  color: var(--accent);
}

.timeline-content p {
  margin: 0;
  line-height: 1.5;
  color: var(--muted);
}

/* Mobile */
@media (max-width: 700px) {
  .timeline-list::before {
    left: 22px;
    transform: none;
  }

  .timeline-item {
    grid-template-columns: 44px 1fr;
    gap: 1rem;
  }

  .timeline-item.left .timeline-content,
  .timeline-item.right .timeline-content {
    grid-column: 2;
    justify-self: stretch;
    text-align: left;
    max-width: none;
  }

  .timeline-dot {
    grid-column: 1;
  }
}

.github-corner {
  position: fixed;
  bottom: 15px;
  right: 15px;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  background: #0d1117;
  color: #ffffff;
  font-family: Arial, sans-serif;
  font-size: 14px;
  text-decoration: none;
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.3);
  transition: transform 0.2s ease, background 0.2s ease;
  z-index: 9999;
}

.github-corner:hover {
  background: #161b22;
  transform: translateY(-2px);
}

.github-corner svg {
  width: 20px;
  height: 20px;
}