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

:root {
  --bg: #f4f6f9;
  --surface: #ffffff;
  --text: #1a2332;
  --muted: #5c6b7a;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --border: #d8dee6;
  --error-bg: #fef2f2;
  --error-border: #fecaca;
  --error-text: #991b1b;
  --shadow: 0 8px 24px rgba(26, 35, 50, 0.08);
}

html {
  font-size: 16px;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.5;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.site-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.site-header__inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--text);
  text-decoration: none;
}

.brand:hover {
  text-decoration: none;
}

.brand__mark {
  width: 2rem;
  height: 2rem;
  border-radius: 0.5rem;
  background: linear-gradient(135deg, #2563eb, #1e40af);
  color: #fff;
  display: grid;
  place-items: center;
  font-size: 0.875rem;
  font-weight: 800;
}

.site-nav {
  display: flex;
  gap: 1.25rem;
  font-size: 0.9375rem;
}

.site-nav a {
  color: var(--muted);
}

.site-nav a:hover,
.site-nav a.is-active {
  color: var(--text);
  text-decoration: none;
}

main {
  max-width: 960px;
  margin: 0 auto;
  padding: 2.5rem 1.5rem 4rem;
}

.hero {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 1rem;
  box-shadow: var(--shadow);
  padding: 2.5rem;
}

.hero h1 {
  margin: 0 0 0.75rem;
  font-size: clamp(1.75rem, 4vw, 2.25rem);
  font-weight: 700;
}

.hero p {
  margin: 0 0 1.5rem;
  color: var(--muted);
  max-width: 42rem;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.625rem 1.125rem;
  border-radius: 0.5rem;
  border: 1px solid transparent;
  font: inherit;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
}

.btn:hover {
  text-decoration: none;
}

.btn--primary {
  background: var(--accent);
  color: #fff;
}

.btn--primary:hover {
  background: var(--accent-hover);
}

.btn--secondary {
  background: var(--surface);
  color: var(--text);
  border-color: var(--border);
}

.features {
  margin-top: 2rem;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
}

.feature {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0.875rem;
  padding: 1.25rem;
}

.feature h2 {
  margin: 0 0 0.5rem;
  font-size: 1rem;
}

.feature p {
  margin: 0;
  color: var(--muted);
  font-size: 0.9375rem;
}

.login-card {
  max-width: 420px;
  margin: 0 auto;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 1rem;
  box-shadow: var(--shadow);
  padding: 2rem;
}

.login-card h1 {
  margin: 0 0 0.5rem;
  font-size: 1.5rem;
}

.login-card__subtitle {
  margin: 0 0 1.5rem;
  color: var(--muted);
  font-size: 0.9375rem;
}

.alert {
  margin-bottom: 1.25rem;
  padding: 0.875rem 1rem;
  border-radius: 0.5rem;
  background: var(--error-bg);
  border: 1px solid var(--error-border);
  color: var(--error-text);
  font-size: 0.9375rem;
}

.form-group {
  margin-bottom: 1rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.375rem;
  font-size: 0.875rem;
  font-weight: 600;
}

.form-group input {
  width: 100%;
  padding: 0.625rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  font: inherit;
  background: #fff;
}

.form-group input:focus {
  outline: 2px solid rgba(37, 99, 235, 0.25);
  border-color: var(--accent);
}

.form-actions {
  margin-top: 1.5rem;
}

.form-actions .btn {
  width: 100%;
}

.site-footer {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 1.5rem 2rem;
  color: var(--muted);
  font-size: 0.8125rem;
}

@media (max-width: 640px) {
  .site-header__inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .hero,
  .login-card {
    padding: 1.5rem;
  }
}