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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  overflow-x: hidden;
}

/* Utilities */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.section {
  padding: var(--space-section) 0;
}

.section-header {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.section-header .subtitle {
  color: var(--color-text-muted);
  font-size: var(--fs-lg);
  margin-top: var(--space-sm);
}

/* Header */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background-color: var(--color-header-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  transition: all var(--transition-base);
}

.site-header.scrolled {
  height: calc(var(--header-height) * 0.85);
  box-shadow: var(--shadow-sm);
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 100%;
}

.logo {
  font-family: var(--font-heading);
  font-size: var(--fs-xl);
  font-weight: var(--fw-extrabold);
  color: var(--color-accent);
  text-decoration: none;
  transition: transform var(--transition-fast);
}

.logo:hover {
  transform: scale(1.05);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.social-links {
  display: flex;
  gap: var(--space-md);
}

.social-link {
  color: var(--color-text-muted);
  transition: color var(--transition-fast), transform var(--transition-fast);
}

.social-link:hover {
  color: var(--color-accent);
  transform: translateY(-2px);
}

/* Main content offset for fixed header */
main {
  padding-top: var(--header-height);
}

/* Headings */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  line-height: 1.2;
  color: var(--color-text);
}

h1 { font-size: var(--fs-3xl); font-weight: var(--fw-extrabold); }
h2 { font-size: var(--fs-2xl); font-weight: var(--fw-bold); }
h3 { font-size: var(--fs-xl); font-weight: var(--fw-semibold); }

/* Theme toggle icon visibility */
[data-theme="dark"] .icon-sun { display: block; }
[data-theme="dark"] .icon-moon { display: none; }
[data-theme="light"] .icon-sun,
:root:not([data-theme]) .icon-sun { display: none; }
[data-theme="light"] .icon-moon,
:root:not([data-theme]) .icon-moon { display: block; }

.theme-toggle svg {
  width: 22px;
  height: 22px;
}

/* Footer tagline */
.footer-tagline {
  color: var(--color-text-muted);
  font-size: var(--fs-sm);
  margin-top: var(--space-md);
  line-height: 1.5;
}

/* Navigation */
.nav-list {
  display: flex;
  gap: var(--space-lg);
  list-style: none;
}

.nav-link {
  color: var(--color-text);
  text-decoration: none;
  font-weight: var(--fw-medium);
  font-size: var(--fs-base);
  position: relative;
  padding: var(--space-xs) 0;
  transition: color var(--transition-fast);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-accent);
  transition: width var(--transition-base);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

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

/* Theme & Menu Toggles */
.theme-toggle,
.menu-toggle {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-text);
  padding: var(--space-xs);
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-full);
  transition: background-color var(--transition-fast);
}

.theme-toggle:hover,
.menu-toggle:hover {
  background-color: var(--color-bg-alt);
}

.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  width: 40px;
  height: 40px;
}

.menu-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background-color: currentColor;
  transition: var(--transition-base);
}

.menu-toggle.is-open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.menu-toggle.is-open span:nth-child(2) {
  opacity: 0;
}

.menu-toggle.is-open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* Footer */
.site-footer {
  background-color: var(--color-text);
  color: var(--color-bg);
  padding: var(--space-4xl) 0 var(--space-xl);
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-2xl);
  margin-bottom: var(--space-3xl);
}

.footer-col h3 {
  font-family: var(--font-heading);
  font-size: var(--fs-lg);
  margin-bottom: var(--space-lg);
  color: var(--color-accent-light);
}

.footer-col ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.footer-col a {
  color: var(--color-text-muted);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.footer-col a:hover {
  color: var(--color-accent);
}

.footer-bottom {
  text-align: center;
  padding-top: var(--space-xl);
  border-top: 1px solid hsla(0, 0%, 100%, 0.1);
  color: var(--color-text-muted);
}

/* Grid System */
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--space-lg); }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--space-lg); }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--space-lg); }

/* Animation Utils */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: all var(--transition-slow);
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Responsive */
@media (max-width: 992px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .menu-toggle { display: flex; }
  
  .main-nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--color-bg);
    padding: var(--space-xl);
    transform: translateX(100%);
    transition: transform var(--transition-spring);
    overflow-y: auto;
  }
  
  .main-nav.is-open {
    transform: translateX(0);
  }
  
  .nav-list {
    flex-direction: column;
    align-items: center;
    gap: var(--space-xl);
  }
  
  .nav-link {
    font-size: var(--fs-xl);
  }
  
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .footer-grid { grid-template-columns: 1fr; }
}