:root {
  color-scheme: light;
  --color-flyway: #1f5fa9;
  --color-liquid-blue: #0ea5e9;
  --color-minor-blue: #4a88c7;
  --color-quench-blue: #d9ecfb;
  --color-cotton-white: #fdfcf8;
  --color-ink: #15324f;
  --color-white: #ffffff;
  --shadow-soft: 0 8px 20px rgba(21, 50, 79, 0.12);
  --radius-soft: 14px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Trebuchet MS", "Verdana", sans-serif;
  color: var(--color-ink);
  background: linear-gradient(180deg, var(--color-cotton-white) 0%, var(--color-quench-blue) 100%);
  line-height: 1.6;
}

header,
.hero {
  background: linear-gradient(135deg, var(--color-flyway), var(--color-minor-blue));
  color: var(--color-cotton-white);
  text-align: center;
  padding: 3rem 1rem 2.5rem;
  border-bottom: 6px solid var(--color-cotton-white);
  box-shadow: var(--shadow-soft);
}

nav {
  background: var(--color-flyway);
  color: var(--color-cotton-white);
  border-top: 2px solid var(--color-quench-blue);
  border-bottom: 2px solid var(--color-quench-blue);
  padding: 0.75rem 1rem;
}

nav a {
  color: var(--color-cotton-white);
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3rem);
  letter-spacing: 0.01em;
}

.tagline {
  font-size: 1.1rem;
  margin-top: 0.75rem;
}

main {
  max-width: 860px;
  margin: 0 auto;
  padding: 2rem 1rem 3rem;
}

section,
.section,
.card {
  background: #eef5fc;
  border: 1px solid var(--color-quench-blue);
  border-left: 6px solid var(--color-flyway);
  padding: 1rem 1.25rem;
  border-radius: var(--radius-soft);
  margin-bottom: 1rem;
  box-shadow: var(--shadow-soft);
}

h2 {
  margin-top: 0;
  color: var(--color-minor-blue);
}

a {
  color: var(--color-liquid-blue);
  text-underline-offset: 3px;
  transition: color 0.2s ease;
}

a:hover,
a:focus-visible {
  color: var(--color-flyway);
}

button,
.button {
  background: var(--color-flyway);
  color: var(--color-cotton-white);
  border: 2px solid var(--color-cotton-white);
  border-radius: 999px;
  padding: 0.6rem 1rem;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 4px 10px rgba(21, 50, 79, 0.18);
  transition: background-color 0.2s ease, transform 0.2s ease;
}

button:hover,
button:focus-visible,
.button:hover,
.button:focus-visible {
  background: var(--color-liquid-blue);
  transform: translateY(-1px);
}

ul {
  margin: 0;
  padding-left: 1.2rem;
}

footer {
  text-align: center;
  padding: 1rem;
  font-weight: 600;
  color: var(--color-flyway);
  border-top: 2px solid var(--color-quench-blue);
  background: var(--color-cotton-white);
}