:root {
  --bg: #ffffff;
  --text: #1f2933;
  --card-bg: #ffffff;
  --accent: #3b82f6;
  --link: #3b82f6;
  --border: #e5e7eb;

  --text-muted: #4b5563;
  --text-subtle: #374151;
  --input-border: #d1d5db;

  --space-1: 0.5rem;
  --space-2: 0.75rem;
  --space-3: 1rem;
  --space-4: 1.5rem;
  --space-5: 2rem;
  --space-6: 3rem;
}

body.dark {
  --bg: #0b1220;
  --text: #e5e7eb;
  --card-bg: #0f172a;
  --accent: #60a5fa;
  --link: #60a5fa;
  --border: #1f2937;

  --text-muted: #cbd5e1;
  --text-subtle: #e2e8f0;
  --input-border: #334155;

  background:
    radial-gradient(
      1000px 600px at 10% 0%,
      rgba(96, 165, 250, 0.1),
      transparent 55%
    ),
    radial-gradient(
      900px 500px at 90% 10%,
      rgba(96, 165, 250, 0.06),
      transparent 60%
    ),
    var(--bg);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  background:
    radial-gradient(
      1000px 600px at 10% 0%,
      rgba(59, 130, 246, 0.1),
      transparent 55%
    ),
    radial-gradient(
      900px 500px at 90% 10%,
      rgba(59, 130, 246, 0.06),
      transparent 60%
    ),
    var(--bg);
  color: var(--text);
  font-family: "Inter", system-ui, sans-serif;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition:
    background-color 0.25s ease,
    color 0.25s ease;
}

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

p {
  margin: 0 0 1rem 0;
}

::selection {
  background: rgba(59, 130, 246, 0.18);
}

/* ================= NAV ================= */

.nav-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-3) var(--space-5);
  background-color: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  position: static;
  top: 0;
  z-index: 1000;
  gap: var(--space-3);
}

body.dark .nav-bar {
  background-color: rgba(15, 23, 42, 0.85);
}

.nav-name {
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--text);
  margin: 0;
  text-decoration: none;
  letter-spacing: -0.02em;
}

.nav-left {
  flex: 1;
}

.nav-links {
  flex: 2;
  display: flex;
  justify-content: center;
  gap: 1.25rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links li a {
  text-decoration: none;
  color: var(--text);
  font-weight: 500;
  padding: 0.5rem 0.75rem;
  border-radius: 8px;
  transition:
    background 0.2s ease,
    color 0.2s ease,
    transform 0.15s ease;
}

.nav-links li a:hover {
  background-color: var(--border);
  transform: translateY(-1px);
}

.nav-right {
  flex: 1;
  display: flex;
  justify-content: flex-end;
}

.toggle-theme {
  background: none;
  border: none;
  font-size: 1.25rem;
  cursor: pointer;
  color: var(--link);
  transition:
    color 0.2s ease-in-out,
    transform 0.15s ease;
  margin-left: var(--space-3);
  font-family: inherit;
}

.toggle-theme:hover {
  color: var(--accent);
  transform: rotate(10deg);
}

/* ================= FOOTER ================= */

.footer {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: var(--space-6) var(--space-3);
  font-size: 0.9rem;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  background-color: var(--card-bg);
  gap: var(--space-3);
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem 1rem;
}

.footer a {
  color: var(--link);
  text-decoration: none;
  font-weight: 500;
  transition:
    color 0.2s ease-in-out,
    transform 0.15s ease;
}

.footer a:hover {
  color: var(--accent);
  transform: translateY(-1px);
}

.powered-by-aws {
  display: flex;
  justify-content: center;
}

.powered-by-aws img {
  height: 30px;
  opacity: 0.8;
  transition:
    opacity 0.2s ease-in-out,
    transform 0.2s ease;
}

.powered-by-aws img:hover {
  opacity: 1;
  transform: scale(1.05);
}

/* ================= UTILITIES ================= */

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: var(--space-6) var(--space-4);
}

.container-narrow {
  max-width: 48rem;
  margin: 0 auto;
  padding: var(--space-6) var(--space-4);
}

.page-title {
  text-align: center;
  font-size: clamp(1.6rem, 2.5vw, 2rem);
  margin-bottom: var(--space-6);
  color: var(--text);
  letter-spacing: -0.02em;
}

/* ================= CARD SYSTEM ================= */

.card {
  background-color: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: var(--space-5);
  box-shadow:
    0 10px 30px rgba(0, 0, 0, 0.06),
    0 1px 0 rgba(255, 255, 255, 0.3) inset;
  transition:
    transform 0.18s ease,
    box-shadow 0.18s ease,
    background-color 0.25s ease,
    border-color 0.25s ease;
}

.card:hover {
  transform: translateY(-3px);
  box-shadow:
    0 16px 40px rgba(0, 0, 0, 0.09),
    0 1px 0 rgba(255, 255, 255, 0.3) inset;
}

.card h2 {
  margin-top: 0;
  font-size: 1.25rem;
  color: var(--text);
  letter-spacing: -0.01em;
}

.card p {
  margin-bottom: 1rem;
  color: var(--text-subtle);
  line-height: 1.65;
}

.card img {
  width: 100%;
  height: auto;
  border-radius: 12px;
  margin: 1.5rem 0;
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.08);
}

/* ================= BUTTONS ================= */

.btn-row {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  margin-top: 1rem;
}

.btn {
  display: inline-block;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.12), rgba(255, 255, 255, 0)),
    var(--accent);
  color: #ffffff;
  padding: 0.7rem 1.25rem;
  border-radius: 10px;
  text-decoration: none;
  font-weight: 650;
  font-size: 0.95rem;
  letter-spacing: -0.01em;
  transition:
    transform 0.15s ease-in-out,
    box-shadow 0.15s ease-in-out,
    background-color 0.2s ease-in-out;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(59, 130, 246, 0.35);
}

.btn:active {
  transform: translateY(0);
  box-shadow: 0 4px 10px rgba(59, 130, 246, 0.25);
}

/* ================= RESPONSIVE ================= */

@media (max-width: 640px) {
  .nav-bar {
    flex-direction: column;
    align-items: flex-start;
    padding: var(--space-3) var(--space-4);
  }

  .nav-links {
    flex-direction: column;
    align-items: flex-start;
    width: 100%;
    gap: 0.5rem;
  }

  .nav-right {
    align-self: flex-end;
  }

  .footer-links {
    flex-direction: column;
    gap: 0.25rem;
  }

  .container,
  .container-narrow {
    padding: var(--space-5) var(--space-3);
  }

  .card {
    padding: var(--space-4);
  }

  .btn-row {
    flex-direction: column;
  }

  .btn {
    width: 100%;
    text-align: center;
  }
}