/* ===== Reset ===== */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif; line-height: 1.6; font-size: 0.875rem; }
a { text-decoration: none; color: inherit; }
ul { list-style: none; }
img { max-width: 100%; display: block; }

/* ===== Theme Variables (Dark = default) ===== */
:root {
  --bg-page:       #0a192f;
  --bg-sidebar:    #11224a;
  --bg-card:       #112240;
  --bg-card-hover: #1a2f70;
  --text-heading:  #ffffff;
  --text-body:     #8892b0;
  --text-sidebar-sub: #ffd787;
  --text-nav:      #8892b0;
  --text-nav-hover:#ffffff;
  --accent:        #4ade80;
  --accent-hover:  #86efac;
  --accent-dim:    #166534;
  --tag-bg:        transparent;
  --tag-text:      #4ade80;
  --tag-border:    rgba(74, 222, 128, 0.4);
  --bullet:        #4ade80;
  --link-hover:    #4ade80;
  --selection-bg:  #166534;
  --toggle-bg:     #112240;
  --toggle-border: #4a5568;
  --highlight-rgb: 29, 78, 216;
  --highlight-alpha: 0.25;
  --demo-popup-bg: #1a334d;
  --glow-r: 74; --glow-g: 222; --glow-b: 128;
  --sidebar-border: rgba(74, 222, 128, 0.12);
  --card-border-hover: rgba(74, 222, 128, 0.35);
}

[data-theme="light"] {
  --bg-page:       #faf5ef;
  --bg-sidebar:    #5c4033;
  --bg-card:       #e8dac8;
  --bg-card-hover: #d4c4ae;
  --text-heading:  #3b2a1a;
  --text-body:     #6b5744;
  --text-sidebar-sub: #ffd787;
  --text-nav:      #d4a574;
  --text-nav-hover:#ffd787;
  --accent:        #c0633a;
  --accent-hover:  #d4764e;
  --accent-dim:    #a04e28;
  --tag-bg:        transparent;
  --tag-text:      #c0633a;
  --tag-border:    rgba(192, 99, 58, 0.4);
  --bullet:        #c0633a;
  --link-hover:    #c0633a;
  --selection-bg:  #c0633a;
  --toggle-bg:     #5c4033;
  --toggle-border: #5c4033;
  --highlight-rgb: 114, 51, 0;
  --highlight-alpha: 0.15;
  --demo-popup-bg: #5e432e;
  --glow-r: 192; --glow-g: 99; --glow-b: 58;
  --sidebar-border: rgba(192, 99, 58, 0.15);
  --card-border-hover: rgba(192, 99, 58, 0.25);
}

/* ===== Selection ===== */
::selection { background: var(--selection-bg); color: #ffffff; }

/* ===== Mouse Highlight ===== */
.mouse-highlight {
  background: radial-gradient(
    600px circle at var(--mouse-x, 0) var(--mouse-y, 0),
    rgba(var(--highlight-rgb), var(--highlight-alpha)),
    transparent 40%
  );
  pointer-events: none;
  position: fixed;
  inset: 0;
  z-index: 9999;
}

/* ===== Page Shell ===== */
.page {
  position: relative;
  background-color: var(--bg-page);
  background-image: radial-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px);
  background-size: 30px 30px;
  transition: background-color 0.3s;
  min-height: 100vh;
}
/* Left panel background color */
.page::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 42%;
  height: 100vh;
  background-color: var(--bg-sidebar);
  border-right: 1px solid var(--sidebar-border);
  transition: background-color 0.3s;
  z-index: 0;
}
.page > * {
  position: relative;
  z-index: 1;
}

/* ===== Theme Toggle ===== */
.theme-toggle {
  position: fixed;
  top: 1.5rem;
  right: 1.5rem;
  z-index: 50;
  padding: 0.5rem;
  border-radius: 9999px;
  background-color: var(--toggle-bg);
  border: 2px solid var(--toggle-border);
  cursor: pointer;
  transition: background-color 0.2s, border-color 0.2s;
  line-height: 0;
}
.theme-toggle svg {
  width: 1.5rem;
  height: 1.5rem;
}
.theme-toggle .icon-sun  { color: #facc15; }
.theme-toggle .icon-moon { color: #111827; }

/* ===== Centered Container (like Brittany Chiang) ===== */
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  justify-content: space-between;
  gap: 4rem;
}

/* ===== Sidebar ===== */
.sidebar {
  position: sticky;
  top: 0;
  width: 40%;
  max-height: 100vh;
  flex-shrink: 0;
  padding-top: 6rem;
  padding-bottom: 2rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

/* Sidebar text */
.sidebar h1 {
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: -0.04em;
  margin-bottom: 1rem;
  cursor: pointer;
  user-select: none;
  color: var(--text-heading);
}
[data-theme="light"] .sidebar h1 { color: #ffe1a6; }

.sidebar h2 {
  font-size: 0.8rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  margin-bottom: 1.5rem;
  color: var(--accent);
  opacity: 0.85;
}
[data-theme="light"] .sidebar h2 { color: var(--accent); opacity: 1; }

.sidebar .tagline {
  margin-bottom: 3rem;
  max-width: 20rem;
  font-weight: 400;
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--text-body);
}
[data-theme="light"] .sidebar .tagline { color: var(--text-sidebar-sub); }

/* Nav */
.sidebar nav {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}
.sidebar nav a {
  font-weight: 700;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  transition: color 0.15s, text-shadow 0.3s, transform 0.15s, letter-spacing 0.2s;
  color: var(--text-nav);
}
.sidebar nav a::before {
  content: '';
  display: inline-block;
  width: 2rem;
  height: 1px;
  background-color: currentColor;
  transition: width 0.2s, background-color 0.15s;
}
.sidebar nav a:hover {
  color: var(--text-nav-hover);
  transform: translateX(4px);
  letter-spacing: 0.14em;
}
.sidebar nav a:hover::before {
  width: 4rem;
}
.sidebar nav a.active {
  color: var(--accent);
  animation: glow 1s ease-in-out infinite;
}
.sidebar nav a.active::before {
  width: 4rem;
  background-color: var(--accent);
}

/* Social links */
.socials {
  display: flex;
  gap: 1rem;
  margin-bottom: 2rem;
}
.socials a {
  color: #8892b0;
  transition: color 0.2s, transform 0.2s;
}
.socials a:hover { color: #ffffff; transform: scale(1.15); }
.socials svg { width: 1.5rem; height: 1.5rem; }

/* ===== Main Content ===== */
.main-content {
  width: 58%;
  max-width: 600px;
  padding-top: 6rem;
  padding-bottom: 6rem;
}
.sections {
  display: flex;
  flex-direction: column;
  gap: 4rem;
}

/* Section headings */
.sections h2 {
  font-size: 1rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 1.5rem;
  color: var(--accent);
}

/* About section border */
#about {
  border: 2px solid var(--card-border-hover);
  border-radius: 0.75rem;
  padding: 2rem;
}

/* Body text in sections */
.section-text {
  color: var(--text-body);
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

/* Tech list grid */
.tech-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.5rem;
  margin-left: 1rem;
}
.tech-list li {
  display: flex;
  align-items: center;
}
.tech-list .bullet, .card-list .bullet {
  margin-right: 0.5rem;
  font-size: 0.875rem;
  color: var(--bullet);
}

/* ===== Cards ===== */
.cards { display: flex; flex-direction: column; gap: 2rem; }

.card {
  position: relative;
  padding: 1.5rem;
  border-radius: 0.5rem;
  background-color: var(--bg-card);
  transition: background-color 0.3s ease;
}
.card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  border: 2px solid var(--card-border-hover);
  border-left: 3px solid var(--accent);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
  opacity: 0;
  transition: opacity 0.3s ease;
  pointer-events: none;
}
.card:hover {
  background-color: var(--bg-card-hover);
}
.card:hover::before {
  opacity: 1;
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 0.5rem;
}
.card-header h3 {
  font-size: 1rem;
  font-weight: 500;
  letter-spacing: -0.01em;
  color: var(--text-heading);
}
.card-header p {
  color: var(--text-body);
}
.card-header span {
  color: var(--text-body);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  white-space: nowrap;
}

.card-list {
  margin-top: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  color: var(--text-body);
}
.card-list li {
  display: flex;
  align-items: flex-start;
}

/* Tags */
.tags {
  margin-top: 1rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.tag {
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  border-radius: 9999px;
  padding: 0.25rem 0.75rem;
  background-color: var(--tag-bg);
  border: 1px solid var(--tag-border);
  color: var(--tag-text);
}

/* Project links */
.project-links {
  display: flex;
  gap: 1rem;
}
.project-links a, .project-links .demo-trigger {
  color: var(--accent);
  font-family: inherit;
  font-size: inherit;
  transition: color 0.2s;
  cursor: pointer;
}
.project-links a:hover, .project-links .demo-trigger:hover {
  color: var(--accent-hover);
}
[data-theme="light"] .project-links a { color: var(--accent-dim); }
[data-theme="light"] .project-links a:hover { color: var(--accent); }
[data-theme="light"] .project-links .demo-trigger { color: var(--accent-dim); }
[data-theme="light"] .project-links .demo-trigger:hover { color: var(--accent); }

/* Demo popup */
.demo-wrapper { position: relative; }
.demo-popup {
  display: none;
  position: absolute;
  left: 0;
  top: 100%;
  margin-top: 0.5rem;
  padding: 0.5rem;
  border-radius: 0.5rem;
  box-shadow: 0 10px 25px rgba(0,0,0,0.3);
  z-index: 10;
  background-color: var(--demo-popup-bg);
}
.demo-wrapper:hover .demo-popup { display: block; }
.demo-popup img { max-width: 300px; border-radius: 0.25rem; }

/* ===== Animated Underline Links ===== */
.arrow-link {
  display: inline-flex;
  align-items: center;
  font-size: 0.875rem;
  transition: color 0.2s;
  color: var(--text-heading);
  margin-left: 1.5rem;
  margin-top: 1rem;
}
.arrow-link:hover { color: var(--link-hover); }

.arrow-link .label {
  position: relative;
}
.arrow-link .label::after {
  content: '';
  position: absolute;
  width: 100%;
  height: 1px;
  bottom: 0;
  left: 0;
  background-color: var(--link-hover);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.3s;
}
.arrow-link:hover .label::after { transform: scaleX(1); }

.arrow-link .arrow {
  margin-left: 0.5rem;
  display: inline-block;
  transition: transform 0.2s;
}
.arrow-link:hover .arrow { transform: translateX(0.5rem); }

/* ===== Fade-in Animations ===== */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out, background-color 0.3s ease;
}
.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== Bottom Spacer ===== */
.bottom-spacer { padding-top: 7rem; }

/* ===== Glow Animation ===== */
@keyframes glow {
  0%, 100% {
    text-shadow:
      0 0 10px rgba(var(--glow-r), var(--glow-g), var(--glow-b), 0.8),
      0 0 20px rgba(var(--glow-r), var(--glow-g), var(--glow-b), 0.6),
      0 0 30px rgba(var(--glow-r), var(--glow-g), var(--glow-b), 0.4);
  }
  50% {
    text-shadow:
      0 0 20px rgba(var(--glow-r), var(--glow-g), var(--glow-b), 1),
      0 0 30px rgba(var(--glow-r), var(--glow-g), var(--glow-b), 0.8),
      0 0 40px rgba(var(--glow-r), var(--glow-g), var(--glow-b), 0.6);
  }
}