:root {
  --background: 195 60% 98%;
  --foreground: 210 35% 16%;
  --primary: 204 80% 38%;
  --secondary: 150 45% 48%;
  --muted: 205 25% 92%;
  --destructive: 0 70% 48%;
  --border: 205 25% 84%;
  --card: 0 0% 100%;

  --shadow-sm: 0 4px 10px hsla(210, 35%, 16%, 0.08);
  --shadow-md: 0 12px 30px hsla(210, 35%, 16%, 0.12);
  --shadow-lg: 0 18px 45px hsla(210, 35%, 16%, 0.16);

  --transition-fast: 0.2s ease;
  --transition-smooth: 0.35s ease;

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 24px;
}

.dark {
  --background: 210 35% 8%;
  --foreground: 195 60% 96%;
  --primary: 204 80% 62%;
  --secondary: 150 45% 58%;
  --muted: 210 25% 18%;
  --destructive: 0 70% 58%;
  --border: 210 20% 28%;
  --card: 210 30% 12%;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: Arial, Helvetica, sans-serif;
  background: hsl(var(--background));
  color: hsl(var(--foreground));
  line-height: 1.6;
}

.site-header {
  background: hsl(var(--card));
  border-bottom: 1px solid hsl(var(--border));
  box-shadow: var(--shadow-sm);
}

.navbar {
  width: min(1100px, 92%);
  margin: auto;
  min-height: 70px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  color: hsl(var(--primary));
  font-weight: bold;
  font-size: 1.35rem;
  text-decoration: none;
}

.menu-button {
  width: 46px;
  height: 46px;
  border: 1px solid hsl(var(--border));
  border-radius: var(--radius-sm);
  background: hsl(var(--card));
  color: hsl(var(--foreground));
  font-size: 1.5rem;
  cursor: pointer;
}

.nav-links {
  display: none;
  list-style: none;
  position: absolute;
  top: 70px;
  left: 0;
  width: 100%;
  background: hsl(var(--card));
  border-bottom: 1px solid hsl(var(--border));
  padding: 12px 4%;
}

.nav-links.show {
  display: block;
}

.nav-links li {
  margin: 8px 0;
}

.nav-links a {
  display: block;
  min-height: 44px;
  padding: 10px 12px;
  color: hsl(var(--foreground));
  text-decoration: none;
  border-radius: var(--radius-sm);
}

.nav-links a:hover,
.nav-links a.active {
  background: hsla(204, 80%, 38%, 0.12);
  color: hsl(var(--primary));
}

.login-main {
  min-height: calc(100vh - 70px);
  display: grid;
  place-items: center;
  padding: 32px 4%;
}

.login-card {
  width: min(430px, 100%);
  background: hsl(var(--card));
  border: 1px solid hsl(var(--border));
  border-radius: var(--radius-lg);
  padding: 30px;
  box-shadow: var(--shadow-md);
}

.login-icon {
  width: 64px;
  height: 64px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  background: hsla(204, 80%, 38%, 0.12);
  color: hsl(var(--primary));
  font-size: 1.8rem;
  margin-bottom: 14px;
}

.login-card h1 {
  margin-bottom: 8px;
}

.login-note {
  color: hsla(210, 35%, 16%, 0.72);
  margin-bottom: 22px;
}

.form-group {
  margin-bottom: 16px;
}

label {
  display: block;
  font-weight: bold;
  margin-bottom: 6px;
}

input {
  width: 100%;
  min-height: 48px;
  font-size: max(16px, 1rem);
  padding: 12px;
  border: 1px solid hsl(var(--border));
  border-radius: var(--radius-sm);
  outline: none;
}

input:focus {
  border-color: hsl(var(--primary));
  box-shadow: 0 0 0 3px hsla(204, 80%, 38%, 0.16);
}

.error-message {
  min-height: 24px;
  color: hsl(var(--destructive));
  margin-bottom: 10px;
  font-weight: bold;
}

.login-button {
  width: 100%;
  min-height: 48px;
  border: 0;
  border-radius: var(--radius-md);
  background: hsl(var(--primary));
  color: white;
  font-weight: bold;
  font-size: 1rem;
  cursor: pointer;
}

.login-button:hover {
  box-shadow: var(--shadow-md);
}

.demo-box {
  margin-top: 20px;
  padding: 14px;
  border-radius: var(--radius-md);
  background: hsla(150, 45%, 48%, 0.12);
  color: hsl(var(--foreground));
}

@media (min-width: 760px) {
  .menu-button {
    display: none;
  }

  .nav-links {
    display: flex;
    position: static;
    width: auto;
    padding: 0;
    border: 0;
    gap: 10px;
  }

  .nav-links li {
    margin: 0;
  }
}