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

:root {
  --color-primary: #1a3a5c;
  --color-primary-light: #2a5a8c;
  --color-accent: #3b82c4;
  --color-bg: #f8f9fa;
  --color-surface: #ffffff;
  --color-sidebar-heading: #d0e4f5;
  --color-sidebar-item: #f5f7fa;
  --color-sidebar-border: #1a3a5c;
  --color-text: #1a1a2e;
  --color-text-muted: #555;
  --color-link: #1a5a8c;
  --color-link-hover: #3b82c4;
  --color-border: #dde3ea;
  --sidebar-width: 220px;
  --content-max: 960px;
  --header-height: auto;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  font-size: 1rem;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--color-link);
  text-decoration: none;
  transition: color 0.15s;
}
a:hover {
  color: var(--color-link-hover);
  text-decoration: underline;
}

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

/* === Site Header === */
.site-header {
  background: var(--color-primary);
  color: #fff;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

.site-header h1 {
  font-size: 1.35rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin: 0;
}

.site-header h1 a {
  color: #fff;
  text-decoration: none;
}
.site-header h1 a:hover {
  color: var(--color-sidebar-heading);
  text-decoration: none;
}

.header-right {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.header-link {
  color: rgba(255,255,255,0.85);
  font-size: 0.85rem;
  text-decoration: none;
  transition: color 0.15s;
}
.header-link:hover {
  color: #fff;
  text-decoration: none;
}

.menu-toggle {
  display: none;
  background: none;
  border: 2px solid rgba(255,255,255,0.5);
  border-radius: 6px;
  color: #fff;
  font-size: 1.5rem;
  cursor: pointer;
  padding: 0.25rem 0.5rem;
  line-height: 1;
}

/* === Page Layout === */
.page-layout {
  display: flex;
  flex: 1;
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
  padding: 1.5rem;
  gap: 1.5rem;
}

/* === Sidebar === */
.sidebar {
  width: var(--sidebar-width);
  flex-shrink: 0;
}

.sidebar-section {
  margin-bottom: 1rem;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  overflow: hidden;
  background: var(--color-surface);
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
}

.sidebar-section h2 {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 0.6rem 0.85rem;
  margin: 0;
  background: var(--color-primary);
  color: #fff;
}

.sidebar-section ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.sidebar-section li {
  border-top: 1px solid var(--color-border);
}

.sidebar-section li:first-child {
  border-top: none;
}

.sidebar-section li a {
  display: block;
  padding: 0.5rem 0.85rem;
  font-size: 0.875rem;
  color: var(--color-text);
  transition: background 0.15s, color 0.15s;
}

.sidebar-section li a:hover {
  background: var(--color-sidebar-heading);
  color: var(--color-primary);
  text-decoration: none;
}

.sidebar-section li.active a {
  background: var(--color-sidebar-heading);
  font-weight: 600;
  color: var(--color-primary);
}

.sidebar-note p {
  padding: 0.6rem 0.85rem;
  font-size: 0.8rem;
  line-height: 1.5;
  color: var(--color-text-muted);
  margin: 0;
}

/* === Main Content === */
.main-content {
  flex: 1;
  min-width: 0;
  background: var(--color-surface);
  border-radius: 8px;
  padding: 1.5rem;
  border: 1px solid var(--color-border);
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
}

.main-content h2 {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--color-border);
}

.main-content p {
  margin-bottom: 1rem;
}

/* === Project Grid (index page) === */
.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.project-card {
  border: 1px solid var(--color-border);
  border-radius: 8px;
  overflow: hidden;
  background: var(--color-surface);
  transition: transform 0.15s, box-shadow 0.15s;
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
}

.project-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 20px rgba(0,0,0,0.1);
}

.project-card a {
  text-decoration: none;
  color: inherit;
  display: block;
}

.project-card img {
  width: 100%;
  aspect-ratio: 3/2;
  object-fit: cover;
  display: block;
  border-bottom: 1px solid var(--color-border);
}

.project-card .card-body {
  padding: 0.75rem;
}

.project-card .card-body h3 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: 0.3rem;
}

.project-card .card-body p {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.4;
}

/* === Project Detail Content === */
.project-description {
  line-height: 1.7;
}

.project-description img {
  border-radius: 6px;
  margin: 0.75rem 0;
  border: 1px solid var(--color-border);
  cursor: zoom-in;
}

.project-description img[align="right"] {
  float: right;
  margin: 0 0 1rem 1.5rem;
  width: min(55%, 500px);
}

.project-description img[align="left"] {
  float: left;
  margin: 0 1.5rem 1rem 0;
  width: min(55%, 500px);
}

/* Full-width images (no align attribute) */
.project-description > img:not([align]) {
  display: block;
  width: min(100%, 600px);
}

.schematic-view img {
  display: block;
  width: min(100%, 550px);
  border: 1px solid var(--color-border);
  border-radius: 6px;
  margin-top: 0.75rem;
  cursor: zoom-in;
}

.schematic-view p,
.schematic-description {
  margin: 1rem 0;
  line-height: 1.7;
}

.schematic-hint {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-top: 0.5rem;
}

/* === Lightbox === */
.lightbox-overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 200;
  background: rgba(0, 0, 0, 0.85);
  cursor: zoom-out;
  overflow: auto;
  padding: 2rem;
}

.lightbox-overlay.active {
  display: flex;
  align-items: start;
  justify-content: center;
}

.lightbox-overlay img {
  max-width: none;
  width: auto;
  height: auto;
  min-width: min(100%, 900px);
  border-radius: 6px;
  box-shadow: 0 4px 30px rgba(0, 0, 0, 0.4);
}

.intro-text {
  font-size: 1rem;
  line-height: 1.7;
  max-width: 700px;
  margin-bottom: 0.5rem;
}

/* === Footer === */
.site-footer {
  text-align: center;
  padding: 1.25rem;
  color: var(--color-text-muted);
  font-size: 0.8rem;
  border-top: 1px solid var(--color-border);
  margin-top: auto;
}

/* === Responsive === */
@media (max-width: 768px) {
  .menu-toggle {
    display: block;
  }

  .page-layout {
    flex-direction: column;
    padding: 1rem;
    gap: 1rem;
  }

  .sidebar {
    width: 100%;
    display: none;
  }

  .sidebar.open {
    display: block;
  }

  .main-content {
    padding: 1rem;
  }

  .project-description img[align="right"],
  .project-description img[align="left"] {
    float: none;
    max-width: 100%;
    margin: 0.75rem 0;
  }

  .project-grid {
    grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
    gap: 1rem;
  }
}

@media (max-width: 480px) {
  .site-header h1 {
    font-size: 1.1rem;
  }

  .project-grid {
    grid-template-columns: 1fr 1fr;
    gap: 0.75rem;
  }
}

/* === Clearfix for floated images === */
.project-description::after {
  content: "";
  display: table;
  clear: both;
}

.next-project {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--color-border);
  text-align: right;
}

.next-project a {
  font-weight: 600;
  color: var(--color-primary);
  text-decoration: none;
}

.next-project a:hover {
  color: var(--color-primary-light);
}