/* ============================================================
   MAIN STYLESHEET — Andy Cheung Portfolio
   ============================================================ */

/* ---- HEADER / NAV ---- */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding-block: var(--space-4);
  background: rgba(10, 10, 15, 0.7);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--color-divider);
  transition: background var(--transition-slow), box-shadow var(--transition-slow);
}

[data-theme='light'] .header {
  background: rgba(244, 244, 248, 0.8);
}

.header--scrolled {
  box-shadow: var(--shadow-md);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-8);
}

/* Logo */
.nav__logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  text-decoration: none;
  flex-shrink: 0;
}

.nav__logo-mark {
  width: 36px;
  height: 36px;
}

.nav__logo-text {
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--color-text);
}

/* Nav links */
.nav__links {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  list-style: none;
}

.nav__link {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-muted);
  position: relative;
}

.nav__link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 1.5px;
  background: var(--color-primary);
  transition: width var(--transition-interactive);
}

.nav__link:hover {
  color: var(--color-text);
}

.nav__link:hover::after,
.nav__link.active::after {
  width: 100%;
}

.nav__link.active {
  color: var(--color-primary);
}

/* Nav actions */
.nav__actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.theme-toggle {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  background: var(--color-surface);
}

.theme-toggle:hover {
  color: var(--color-text);
  border-color: var(--color-primary);
  background: var(--color-primary-subtle);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-5);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  line-height: 1.4;
}

.btn--primary {
  background: var(--color-primary);
  color: white;
  box-shadow: var(--glow-primary);
}

.btn--primary:hover {
  background: var(--color-primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 0 40px rgba(124, 109, 252, 0.4);
}

.btn--ghost {
  border: 1px solid var(--color-border);
  color: var(--color-text-muted);
  background: transparent;
}

.btn--ghost:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-subtle);
}

/* Mobile hamburger */
.nav__hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  width: 24px;
  cursor: pointer;
  background: none;
  border: none;
  padding: 4px;
}

.nav__hamburger span {
  display: block;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: all var(--transition-interactive);
}

.nav__hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav__hamburger.open span:nth-child(2) { opacity: 0; }
.nav__hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Mobile menu */
.nav__mobile {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-divider);
  padding: var(--space-6);
  flex-direction: column;
  gap: var(--space-4);
}

.nav__mobile.open {
  display: flex;
}

.nav__mobile .nav__link {
  font-size: var(--text-base);
  padding-block: var(--space-2);
}

/* ---- HERO SECTION ---- */
.hero {
  min-height: 100dvh;
  display: grid;
  place-items: center;
  padding-block: var(--space-32);
  padding-top: calc(var(--space-32) + 64px);
  position: relative;
  overflow: hidden;
}

.hero__grid-bg {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--color-divider) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-divider) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse 80% 60% at 50% 50%, black 30%, transparent 100%);
  opacity: 0.4;
  pointer-events: none;
}

.hero__glow {
  position: absolute;
  top: 20%;
  left: 30%;
  width: 600px;
  height: 600px;
  background: radial-gradient(ellipse, rgba(124, 109, 252, 0.12) 0%, transparent 70%);
  pointer-events: none;
}

.hero__inner {
  position: relative;
  z-index: 1;
  text-align: center;
  max-width: 900px;
  margin-inline: auto;
  padding-inline: var(--space-6);
}

.hero__eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: var(--space-6);
}

.hero__dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-primary);
  animation: pulse 2s ease infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.85); }
}

.hero__name {
  font-family: var(--font-display);
  font-size: var(--text-hero);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 0.95;
  margin-bottom: var(--space-6);
}

.hero__title {
  font-size: var(--text-xl);
  font-weight: 400;
  color: var(--color-text-muted);
  margin-bottom: var(--space-6);
  font-family: var(--font-body);
}

.hero__title strong {
  color: var(--color-text);
  font-weight: 600;
}

.hero__tagline {
  font-size: var(--text-base);
  color: var(--color-text-muted);
  max-width: 52ch;
  margin-inline: auto;
  margin-bottom: var(--space-10);
  line-height: 1.7;
}

.hero__actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-4);
  flex-wrap: wrap;
}

.hero__scroll {
  position: absolute;
  bottom: var(--space-8);
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-2);
  color: var(--color-text-faint);
  font-size: var(--text-xs);
  font-family: var(--font-mono);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  animation: float 3s ease infinite;
}

.hero__scroll svg {
  margin: 0 auto;
}

@keyframes float {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50% { transform: translateX(-50%) translateY(6px); }
}

/* ---- SECTION SHARED ---- */
.section {
  padding-block: clamp(var(--space-16), 10vw, var(--space-32));
}

.section__header {
  margin-bottom: clamp(var(--space-10), 5vw, var(--space-16));
}

.section__label {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-bottom: var(--space-4);
}

.section__label::before {
  content: '';
  width: 24px;
  height: 1.5px;
  background: var(--color-primary);
}

.section__title {
  font-size: var(--text-2xl);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.05;
}

.section__subtitle {
  font-size: var(--text-base);
  color: var(--color-text-muted);
  margin-top: var(--space-4);
  max-width: 60ch;
}

/* ---- ABOUT STRIP ---- */
.about-strip {
  background: var(--color-surface);
  border-top: 1px solid var(--color-divider);
  border-bottom: 1px solid var(--color-divider);
}

.about-strip__inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: clamp(var(--space-10), 6vw, var(--space-24));
  align-items: center;
}

.about-strip__avatar {
  position: relative;
}

.about-strip__avatar-img {
  width: 100%;
  max-width: 360px;
  aspect-ratio: 1;
  border-radius: var(--radius-xl);
  object-fit: cover;
  border: 1px solid var(--color-border);
}

.about-strip__avatar-ring {
  position: absolute;
  inset: -8px;
  border-radius: calc(var(--radius-xl) + 8px);
  border: 1px solid var(--color-primary-glow);
  pointer-events: none;
}

.avatar-placeholder {
  width: 100%;
  max-width: 360px;
  aspect-ratio: 1;
  border-radius: var(--radius-xl);
  background: var(--color-surface-2);
  border: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-3);
}

.avatar-initials {
  font-family: var(--font-display);
  font-size: var(--text-3xl);
  font-weight: 800;
  letter-spacing: -0.04em;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.about-strip__content {
  padding-block: var(--space-10);
}

.about-strip__bio {
  font-size: var(--text-base);
  color: var(--color-text-muted);
  line-height: 1.75;
  margin-bottom: var(--space-6);
}

.about-strip__bio + .about-strip__bio {
  margin-top: var(--space-4);
}

.fun-fact {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  background: var(--color-primary-subtle);
  border: 1px solid var(--color-primary-glow);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin-top: var(--space-6);
}

.fun-fact__icon {
  font-size: 1.2em;
  flex-shrink: 0;
}

/* ---- SKILLS ---- */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-4);
}

.skill-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  transition: border-color var(--transition-interactive), transform var(--transition-interactive), box-shadow var(--transition-interactive);
}

.skill-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
  box-shadow: var(--glow-primary);
}

.skill-card__icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background: var(--color-primary-subtle);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-4);
  color: var(--color-primary);
}

.skill-card__title {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 700;
  margin-bottom: var(--space-2);
}

.skill-card__body {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.65;
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-top: var(--space-4);
}

.tag {
  font-size: var(--text-xs);
  font-family: var(--font-mono);
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-full);
  background: var(--color-surface-offset);
  border: 1px solid var(--color-border);
  color: var(--color-text-muted);
  white-space: nowrap;
}

.tag--accent {
  background: var(--color-accent-subtle);
  border-color: rgba(34, 211, 238, 0.2);
  color: var(--color-accent);
}

.tag--primary {
  background: var(--color-primary-subtle);
  border-color: var(--color-primary-glow);
  color: var(--color-primary);
}

/* ---- WORK / PROJECTS ---- */
.work-grid {
  display: grid;
  gap: var(--space-6);
}

.project-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  overflow: hidden;
  display: grid;
  grid-template-columns: 1fr 1fr;
  min-height: 380px;
  text-decoration: none;
  transition: border-color var(--transition-interactive), box-shadow var(--transition-interactive), transform var(--transition-interactive);
}

.project-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--glow-primary);
  transform: translateY(-3px);
}

.project-card--featured {
  grid-template-columns: 1fr;
  grid-template-rows: auto;
}

@media (min-width: 768px) {
  .project-card--featured {
    grid-template-columns: 1.2fr 1fr;
  }
}

.project-card__visual {
  position: relative;
  overflow: hidden;
  min-height: 240px;
  background: var(--color-surface-2);
}

.project-card__visual-bg {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-size: clamp(4rem, 10vw, 8rem);
  font-weight: 800;
  letter-spacing: -0.06em;
  opacity: 0.08;
  user-select: none;
  color: var(--color-primary);
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.project-card:hover .project-card__visual-bg {
  opacity: 0.14;
  transform: scale(1.05);
}

.project-card__badge {
  position: absolute;
  top: var(--space-4);
  left: var(--space-4);
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-1) var(--space-3);
  background: rgba(10, 10, 15, 0.8);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-family: var(--font-mono);
  backdrop-filter: blur(8px);
  color: var(--color-text-muted);
}

.project-card__content {
  padding: var(--space-8) var(--space-8);
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.project-card__eyebrow {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
  flex-wrap: wrap;
}

.project-card__title {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: var(--space-3);
  color: var(--color-text);
}

.project-card__desc {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.7;
  margin-bottom: var(--space-6);
  max-width: 40ch;
}

.project-card__meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  margin-bottom: var(--space-6);
}

.meta-item {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.meta-item__label {
  font-size: var(--text-xs);
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-faint);
}

.meta-item__value {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text);
}

.project-card__stat {
  font-size: var(--text-xs);
  color: var(--color-primary);
  font-family: var(--font-mono);
  padding: var(--space-2) var(--space-4);
  background: var(--color-primary-subtle);
  border: 1px solid var(--color-primary-glow);
  border-radius: var(--radius-md);
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
}

.project-card__link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-primary);
  margin-top: var(--space-4);
}

.project-card__link svg {
  transition: transform var(--transition-interactive);
}

.project-card:hover .project-card__link svg {
  transform: translateX(4px);
}

/* 2-col grid for smaller cards */
.work-grid--two {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-6);
}

.project-card--small {
  grid-template-columns: 1fr;
  min-height: 300px;
}

.project-card--small .project-card__visual {
  min-height: 160px;
}

/* ---- STATS ROW ---- */
.stats-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-1);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  overflow: hidden;
}

.stat-item {
  padding: var(--space-8) var(--space-8);
  background: var(--color-surface);
  border-right: 1px solid var(--color-border);
  text-align: center;
}

.stat-item:last-child {
  border-right: none;
}

.stat-item__value {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 800;
  letter-spacing: -0.04em;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-item__label {
  font-size: var(--text-xs);
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-muted);
  margin-top: var(--space-2);
}

/* ---- MOTION SECTION ---- */
.motion-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-10);
  text-align: center;
}

.motion-links {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-4);
  margin-top: var(--space-8);
  flex-wrap: wrap;
}

/* ---- CONTACT ---- */
.contact-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: clamp(var(--space-10), 6vw, var(--space-24));
  align-items: start;
}

.contact-links {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  margin-top: var(--space-8);
}

.contact-link {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  padding: var(--space-4) var(--space-5);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  color: var(--color-text-muted);
  text-decoration: none;
  font-size: var(--text-sm);
}

.contact-link:hover {
  border-color: var(--color-primary);
  color: var(--color-text);
  background: var(--color-primary-subtle);
}

.contact-link__icon {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  background: var(--color-surface-offset);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  color: var(--color-primary);
}

.contact-link__text {
  flex: 1;
}

.contact-link__label {
  display: block;
  font-size: var(--text-xs);
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-faint);
  margin-bottom: 2px;
}

.contact-link__value {
  font-weight: 500;
  color: var(--color-text);
}

/* ---- FOOTER ---- */
.footer {
  border-top: 1px solid var(--color-divider);
  padding-block: var(--space-8);
}

.footer__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  flex-wrap: wrap;
}

.footer__copy {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  font-family: var(--font-mono);
}

.footer__links {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  list-style: none;
}

.footer__link {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}

.footer__link:hover {
  color: var(--color-primary);
}

/* ---- DIVIDER ---- */
.section-divider {
  height: 1px;
  background: var(--color-divider);
}

/* ---- BACK TO TOP ---- */
.back-top {
  position: fixed;
  bottom: var(--space-8);
  right: var(--space-8);
  width: 44px;
  height: 44px;
  border-radius: var(--radius-full);
  background: var(--color-primary);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--glow-primary);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-interactive), transform var(--transition-interactive);
  z-index: 50;
}

.back-top.visible {
  opacity: 1;
  pointer-events: auto;
}

.back-top:hover {
  transform: translateY(-3px);
}

/* ---- RESPONSIVE ---- */
@media (max-width: 900px) {
  .about-strip__inner {
    grid-template-columns: 1fr;
  }
  .about-strip__avatar {
    display: none;
  }
  .contact-inner {
    grid-template-columns: 1fr;
  }
  .work-grid--two {
    grid-template-columns: 1fr;
  }
  .project-card {
    grid-template-columns: 1fr;
  }
  .project-card--featured {
    grid-template-columns: 1fr;
  }
  .stats-row {
    grid-template-columns: 1fr 1fr;
  }
  .stat-item {
    border-right: none;
    border-bottom: 1px solid var(--color-border);
  }
  .stat-item:nth-child(odd) {
    border-right: 1px solid var(--color-border);
  }
}

@media (max-width: 640px) {
  .nav__links { display: none; }
  .nav__actions .btn { display: none; }
  .nav__hamburger { display: flex; }
  .hero__name { font-size: clamp(2.5rem, 12vw, 6rem); }
  .stats-row { grid-template-columns: 1fr; }
  .stat-item { border-right: none; }
  .back-top { bottom: var(--space-5); right: var(--space-5); }
}

/* ---- SCROLL ANIMATIONS ---- */
.fade-up {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s cubic-bezier(0.16, 1, 0.3, 1), transform 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

.fade-up.visible {
  opacity: 1;
  transform: translateY(0);
}

.stagger-1 { transition-delay: 0.1s; }
.stagger-2 { transition-delay: 0.2s; }
.stagger-3 { transition-delay: 0.3s; }
.stagger-4 { transition-delay: 0.4s; }