/* reset & base */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}
body {
  font-family: 'Inter', 'Segoe UI', Roboto, Arial, sans-serif;
  font-size: 1rem;
  line-height: 1.6;
  color: #e0e6ed;
  background-color: #0a1f3d;
  -webkit-font-smoothing: antialiased;
}
h1, h2, h3 {
  font-family: Impact, 'Helvetica Neue', Arial, sans-serif;
  font-weight: normal;
  line-height: 1.2;
  color: #ffffff;
}
a {
  color: #39ff14;
  text-decoration: none;
}
a:hover,
a:focus-visible {
  color: #ff6b35;
  outline: 2px solid #ff6b35;
  outline-offset: 2px;
}
ul { list-style: none; }
img, svg { display: block; max-width: 100%; }
button { cursor: pointer; font: inherit; border: none; background: none; }
.skip-link {
  position: absolute;
  top: -100%;
  left: 0;
  padding: 0.5rem 1rem;
  background: #0d2b52;
  color: #39ff14;
  z-index: 9999;
  transition: top 0.3s;
}
.skip-link:focus {
  top: 0;
}

/* variables */
:root {
  --color-primary: #0a1f3d;
  --color-accent: #39ff14;
  --color-secondary-accent: #ff6b35;
  --color-text: #e0e6ed;
  --color-heading: #ffffff;
  --color-card-bg: rgba(10,31,61,0.85);
  --color-panel-bg: #0d2b52;
  --color-neutral-light: #2a3f5f;
  --color-danger: #ff3333;
  --font-heading: Impact, 'Helvetica Neue', Arial, sans-serif;
  --font-body: 'Inter', 'Segoe UI', Roboto, Arial, sans-serif;
  --font-mono: 'Source Code Pro', Consolas, monospace;
  --header-width: 250px;
  --content-max-width: 1200px;
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
}

/* header – desktop side rail */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--header-width);
  height: 100vh;
  background: var(--color-panel-bg);
  border-right: 1px solid var(--color-neutral-light);
  z-index: 100;
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}
.header__inner {
  display: flex;
  flex-direction: column;
  height: 100%;
  padding: var(--spacing-lg) var(--spacing-md);
}
.logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  color: #ffffff;
  font-family: var(--font-heading);
  font-size: 1.2rem;
  margin-bottom: var(--spacing-xl);
}
.logo__icon {
  display: flex;
  color: var(--color-accent);
}
.nav-toggle {
  display: none; /* hidden on desktop */
}
.nav {
  flex: 1;
}
.nav__list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}
.nav__link {
  display: block;
  padding: var(--spacing-sm) var(--spacing-md);
  color: var(--color-text);
  font-family: var(--font-mono);
  font-size: 0.9rem;
  letter-spacing: 0.05em;
  border-left: 3px solid transparent;
  transition: border-color 0.3s, background 0.3s, color 0.3s;
}
.nav__link:hover,
.nav__link:focus-visible {
  background: rgba(57,255,20,0.08);
  color: var(--color-accent);
  border-left-color: var(--color-accent);
}
.nav__link[aria-current="page"] {
  border-left-color: var(--color-accent);
  background: rgba(57,255,20,0.12);
  color: var(--color-accent);
  font-weight: bold;
}
.header__cta {
  margin-top: var(--spacing-lg);
  text-align: center;
}

/* mobile header overrides */
@media (max-width: 768px) {
  .header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: auto;
    flex-direction: row;
    align-items: center;
    border-right: none;
    border-bottom: 1px solid var(--color-neutral-light);
    padding: var(--spacing-sm) var(--spacing-md);
    min-height: 60px;
    background: rgba(13,43,82,0.95);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    z-index: 100;
  }
  .header__inner {
    flex-direction: row;
    align-items: center;
    width: 100%;
    padding: 0;
    height: auto;
  }
  .logo {
    margin-bottom: 0;
    margin-right: auto;
    font-size: 1rem;
  }
  .nav-toggle {
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 4px;
    width: 32px;
    height: 32px;
    border: none;
    background: transparent;
    cursor: pointer;
  }
  .nav-toggle__bar {
    display: block;
    width: 100%;
    height: 2px;
    background: #ffffff;
    transition: transform 0.3s, opacity 0.3s;
  }
  .nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1) {
    transform: translateY(6px) rotate(45deg);
  }
  .nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2) {
    opacity: 0;
  }
  .nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(3) {
    transform: translateY(-6px) rotate(-45deg);
  }
  .nav {
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background: rgba(13,43,82,0.98);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
    transition: transform 0.4s ease, opacity 0.4s ease;
    padding: var(--spacing-md);
  }
  .nav[data-open] {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }
  .nav__list {
    flex-direction: column;
  }
  .nav__link {
    border-left: none;
    border-bottom: 1px solid var(--color-neutral-light);
    padding: var(--spacing-sm) 0;
  }
  .header__cta {
    display: none; /* hidden on mobile to save space, available via nav */
  }
}

/* footer */
.footer {
  background: #0a1f3d;
  border-top: 2px solid var(--color-neutral-light);
  padding: var(--spacing-xl) var(--spacing-md);
  color: var(--color-text);
}
.footer__inner {
  max-width: var(--content-max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: var(--spacing-lg);
  align-items: start;
}
.footer__brand {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-family: var(--font-heading);
  font-size: 1.2rem;
  color: #ffffff;
}
.footer__links {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}
.footer__links a {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--color-text);
  transition: color 0.3s;
}
.footer__links a:hover,
.footer__links a:focus-visible {
  color: var(--color-accent);
}
.footer__contact {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  font-size: 0.875rem;
  color: rgba(224,230,237,0.7);
}
.footer__contact span {
  display: block;
}
.footer__copyright {
  grid-column: 1 / -1;
  border-top: 1px solid var(--color-neutral-light);
  padding-top: var(--spacing-md);
  margin-top: var(--spacing-md);
  text-align: center;
  font-size: 0.8rem;
  color: rgba(224,230,237,0.5);
}
@media (max-width: 768px) {
  .footer__inner {
    grid-template-columns: 1fr;
    text-align: center;
  }
  .footer__brand {
    justify-content: center;
  }
  .footer__links {
    align-items: center;
  }
  .footer__contact {
    align-items: center;
  }
}

/* scroll progress bar */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 4px;
  background: linear-gradient(90deg, var(--color-accent), var(--color-secondary-accent));
  z-index: 9998;
  transition: width 0.1s linear;
  pointer-events: none;
}
@media (prefers-reduced-motion: reduce) {
  .scroll-progress {
    display: none;
  }
}

/* back to top */
.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--color-panel-bg);
  border: 2px solid var(--color-accent);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-accent);
  font-size: 1.5rem;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s, visibility 0.3s, transform 0.3s;
  z-index: 9997;
  transform: translateY(20px);
}
.back-to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.back-to-top:hover,
.back-to-top:focus-visible {
  background: var(--color-accent);
  color: var(--color-primary);
  border-color: var(--color-accent);
}
@media (prefers-reduced-motion: reduce) {
  .back-to-top {
    display: none;
  }
}

/* buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: 0.75rem 1.5rem;
  border: 2px solid transparent;
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  transition: background 0.3s, color 0.3s, border-color 0.3s, transform 0.2s;
  border-radius: 4px;
}
.btn:focus-visible {
  outline: 2px solid var(--color-secondary-accent);
  outline-offset: 2px;
}
.btn--primary {
  background: var(--color-accent);
  color: var(--color-primary);
  border-color: var(--color-accent);
}
.btn--primary:hover,
.btn--primary:focus-visible {
  background: transparent;
  color: var(--color-accent);
  border-color: var(--color-accent);
}
.btn--secondary {
  background: transparent;
  color: var(--color-accent);
  border-color: var(--color-accent);
}
.btn--secondary:hover,
.btn--secondary:focus-visible {
  background: var(--color-accent);
  color: var(--color-primary);
}

/* utility container */
.container {
  max-width: var(--content-max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

/* page main content offset for desktop sidebar */
body {
  padding-left: var(--header-width);
}
@media (max-width: 768px) {
  body {
    padding-left: 0;
    padding-top: 60px; /* mobile header height */
  }
}

/* focus-visible global */
*:focus-visible {
  outline: 2px solid var(--color-secondary-accent);
  outline-offset: 2px;
}

/* reduced motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}