/* ==========================================
   Variables
   ========================================== */
:root {
  /* Color Palette */
  --color-bg: #f7fbff; /* soft ice background */
  --color-surface: #ffffff; /* pure white cards */
  --color-surface-alt: #f1f5fb;
  --color-text: #0f172a; /* deep navy */
  --color-text-soft: #4b5563;
  --color-primary: #1d82ff; /* sky blue CTA */
  --color-primary-soft: #e1efff;
  --color-primary-strong: #0050c8;
  --color-success: #16a34a;
  --color-warning: #f59e0b;
  --color-danger: #ef4444;

  --color-gray-50: #f9fafb;
  --color-gray-100: #f3f4f6;
  --color-gray-200: #e5e7eb;
  --color-gray-300: #d1d5db;
  --color-gray-400: #9ca3af;
  --color-gray-500: #6b7280;
  --color-gray-600: #4b5563;
  --color-gray-700: #374151;
  --color-gray-800: #1f2933;
  --color-gray-900: #111827;

  /* Gradients (for light, airy hero/CTAs) */
  --gradient-hero: radial-gradient(circle at top, #e5f3ff 0, #f7fbff 55%, #ffffff 100%);
  --gradient-primary-soft: linear-gradient(135deg, #e1efff, #c4e3ff);

  /* Typography */
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Noto Sans', sans-serif;
  --font-heading: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Noto Sans', sans-serif;

  --font-size-xs: 0.75rem;   /* 12px */
  --font-size-sm: 0.875rem;  /* 14px */
  --font-size-base: 1rem;    /* 16px */
  --font-size-lg: 1.125rem;  /* 18px */
  --font-size-xl: 1.25rem;   /* 20px */
  --font-size-2xl: 1.5rem;   /* 24px */
  --font-size-3xl: 1.875rem; /* 30px */
  --font-size-4xl: 2.25rem;  /* 36px */
  --font-size-5xl: 3rem;     /* 48px */

  --line-height-tight: 1.2;
  --line-height-snug: 1.35;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.7;

  /* Spacing scale (0–96px) */
  --space-0: 0;
  --space-1: 0.25rem;  /* 4px */
  --space-2: 0.5rem;   /* 8px */
  --space-3: 0.75rem;  /* 12px */
  --space-4: 1rem;     /* 16px */
  --space-5: 1.25rem;  /* 20px */
  --space-6: 1.5rem;   /* 24px */
  --space-8: 2rem;     /* 32px */
  --space-10: 2.5rem;  /* 40px */
  --space-12: 3rem;    /* 48px */
  --space-16: 4rem;    /* 64px */
  --space-20: 5rem;    /* 80px */
  --space-24: 6rem;    /* 96px */

  /* Radius */
  --radius-sm: 0.375rem; /* 6px */
  --radius-md: 0.75rem;  /* 12px */
  --radius-lg: 1.25rem;  /* 20px */
  --radius-pill: 999px;

  /* Shadows (soft, airy) */
  --shadow-sm: 0 6px 18px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 14px 40px rgba(15, 23, 42, 0.10);
  --shadow-soft-focus: 0 0 0 3px rgba(29, 130, 255, 0.18);

  /* Transitions & Motion */
  --transition-fast: 150ms ease-out;
  --transition-normal: 220ms ease-out;
  --transition-slow: 320ms ease-out;

  /* Layout */
  --layout-max-width: 1120px;
  --layout-gutter: 1.25rem;
}

@media (prefers-reduced-motion: reduce) {
  :root {
    --transition-fast: 0ms;
    --transition-normal: 0ms;
    --transition-slow: 0ms;
  }
}

/* ==========================================
   Reset / Normalize
   ========================================== */
*, *::before, *::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  text-size-adjust: 100%;
}

body {
  margin: 0;
}

h1, h2, h3, h4, h5, h6,
p,
figure,
blockquote,
dl,
dd {
  margin: 0;
}

ul, ol {
  margin: 0;
  padding: 0;
}

/* Required by spec / project */
ul {
  list-style: none !important;
}

img,
picture,
video,
canvas,
svg {
  display: block;
  max-width: 100%;
}

input,
button,
textarea,
select {
  font: inherit;
}

button {
  border: none;
  background: none;
  padding: 0;
  cursor: pointer;
}

:focus {
  outline: none;
}

/* ==========================================
   Base Styles
   ========================================== */
body {
  min-height: 100vh;
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  line-height: var(--line-height-relaxed);
  color: var(--color-text);
  background: var(--gradient-hero);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: var(--line-height-tight);
  color: var(--color-text);
}

h1 {
  font-size: var(--font-size-4xl);
  letter-spacing: -0.03em;
  margin-bottom: var(--space-4);
}

h2 {
  font-size: var(--font-size-3xl);
  letter-spacing: -0.02em;
  margin-bottom: var(--space-4);
}

h3 {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--space-3);
}

h4 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-2);
}

p {
  margin-bottom: var(--space-4);
  color: var(--color-text-soft);
}

p:last-child {
  margin-bottom: 0;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast), opacity var(--transition-fast);
}

a:hover {
  color: var(--color-primary-strong);
}

a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
}

strong {
  font-weight: 600;
}

hr {
  border: none;
  border-top: 1px solid var(--color-gray-200);
  margin: var(--space-8) 0;
}

/* ==========================================
   Accessibility & Focus States
   ========================================== */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}

/* Screen-reader only */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ==========================================
   Layout Utilities
   ========================================== */
.container {
  width: 100%;
  max-width: var(--layout-max-width);
  margin-inline: auto;
  padding-inline: var(--layout-gutter);
}

.section {
  padding-block: var(--space-12);
}

.section--tight {
  padding-block: var(--space-8);
}

.section--hero {
  padding-block: var(--space-16);
}

/* Flex utilities */
.flex {
  display: flex;
}

.inline-flex {
  display: inline-flex;
}

.flex-center {
  display: flex;
  align-items: center;
  justify-content: center;
}

.flex-between {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.flex-column {
  display: flex;
  flex-direction: column;
}

.flex-wrap {
  flex-wrap: wrap;
}

.gap-2 {
  gap: var(--space-2);
}

.gap-3 {
  gap: var(--space-3);
}

.gap-4 {
  gap: var(--space-4);
}

.gap-6 {
  gap: var(--space-6);
}

/* Grid utilities */
.grid {
  display: grid;
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-6);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-6);
}

@media (max-width: 768px) {
  .grid-2,
  .grid-3 {
    grid-template-columns: 1fr;
  }
}

/* Spacing utilities (limited set) */
.mt-0 { margin-top: 0; }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }
.mb-0 { margin-bottom: 0; }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }
.pt-8 { padding-top: var(--space-8); }
.pb-8 { padding-bottom: var(--space-8); }

.text-center { text-align: center; }
.text-right { text-align: right; }

.w-full {
  width: 100%;
}

/* ==========================================
   Navigation & Header helpers
   ========================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(247, 251, 255, 0.9);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(148, 163, 184, 0.18);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-block: var(--space-3);
}

.site-logo {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
}

.site-logo__mark {
  width: 34px;
  height: 34px;
  border-radius: 1rem;
  background: var(--gradient-primary-soft);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-sm);
}

.site-name {
  font-size: var(--font-size-lg);
  font-weight: 700;
  letter-spacing: -0.02em;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.main-nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.main-nav__link {
  font-size: var(--font-size-sm);
  padding: 0.35rem 0.6rem;
  border-radius: var(--radius-pill);
  color: var(--color-text-soft);
}

.main-nav__link--active,
.main-nav__link:hover {
  color: var(--color-text);
  background-color: rgba(226, 239, 255, 0.9);
}

/* Burger / nav-toggle control
   Required: .nav-toggle { flex-direction: column; } */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 4px;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-pill);
  background-color: rgba(255, 255, 255, 0.9);
  box-shadow: var(--shadow-sm);
}

.nav-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  border-radius: 999px;
  background-color: var(--color-text);
  transition: transform var(--transition-normal), opacity var(--transition-normal), background-color var(--transition-fast);
}

.nav-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

@media (max-width: 960px) {
  .site-header__inner {
    gap: var(--space-2);
  }

  .main-nav {
    position: fixed;
    inset: 64px 0 auto 0;
    padding: var(--space-4) var(--layout-gutter) var(--space-6);
    background: rgba(247, 251, 255, 0.98);
    border-bottom: 1px solid rgba(148, 163, 184, 0.18);
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-4);
    transform: translateY(-120%);
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-normal), transform var(--transition-normal);
  }

  .main-nav--open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .main-nav__list {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-2);
  }

  .nav-toggle {
    display: inline-flex;
  }
}

/* ==========================================
   Buttons
   ========================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.7rem 1.4rem;
  border-radius: var(--radius-pill);
  border: 1px solid transparent;
  font-size: var(--font-size-sm);
  font-weight: 600;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  text-decoration: none;
  cursor: pointer;
  transition: background-color var(--transition-normal), border-color var(--transition-normal), color var(--transition-normal), box-shadow var(--transition-normal), transform var(--transition-fast);
}

.btn--primary {
  background: linear-gradient(135deg, #1d82ff, #4da2ff);
  color: #ffffff;
  box-shadow: var(--shadow-md);
}

.btn--primary:hover {
  background: linear-gradient(135deg, #1764d4, #337ef1);
  transform: translateY(-1px);
  box-shadow: 0 18px 40px rgba(15, 23, 42, 0.18);
}

.btn--secondary {
  background-color: rgba(255, 255, 255, 0.95);
  color: var(--color-text);
  border-color: rgba(148, 163, 184, 0.6);
  box-shadow: var(--shadow-sm);
}

.btn--secondary:hover {
  background-color: #ffffff;
  border-color: var(--color-primary);
}

.btn--ghost {
  background-color: transparent;
  color: var(--color-text-soft);
  border-color: transparent;
}

.btn--ghost:hover {
  background-color: rgba(226, 239, 255, 0.7);
  color: var(--color-text);
}

.btn:disabled,
.btn[aria-disabled="true"] {
  opacity: 0.6;
  cursor: not-allowed;
  box-shadow: none;
}

.btn:focus-visible {
  outline: none;
  box-shadow: var(--shadow-soft-focus);
}

/* ==========================================
   Form Elements
   ========================================== */
label {
  display: inline-block;
  margin-bottom: var(--space-2);
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text);
}

input[type="text"],
input[type="email"],
input[type="tel"],
input[type="search"],
input[type="number"],
textarea,
select {
  width: 100%;
  padding: 0.7rem 0.9rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-gray-200);
  background-color: #ffffff;
  color: var(--color-text);
  font-size: var(--font-size-sm);
  line-height: var(--line-height-normal);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast), background-color var(--transition-fast);
}

input::placeholder,
textarea::placeholder {
  color: var(--color-gray-400);
}

textarea {
  min-height: 140px;
  resize: vertical;
}

input:focus-visible,
textarea:focus-visible,
select:focus-visible {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: var(--shadow-soft-focus);
}

input:disabled,
textarea:disabled,
select:disabled {
  background-color: var(--color-gray-50);
  color: var(--color-gray-500);
  cursor: not-allowed;
}

.form-row {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
}

.form-row--inline {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-4);
}

@media (max-width: 640px) {
  .form-row--inline {
    grid-template-columns: 1fr;
  }
}

.form-hint {
  font-size: var(--font-size-xs);
  color: var(--color-gray-500);
}

.form-error {
  font-size: var(--font-size-xs);
  color: var(--color-danger);
}

/* ==========================================
   Cards & Surfaces
   ========================================== */
.card {
  background-color: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
  border: 1px solid rgba(148, 163, 184, 0.18);
}

.card--soft {
  background: linear-gradient(145deg, #ffffff, #f4f7fb);
}

.card__header {
  margin-bottom: var(--space-4);
}

.card__title {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-1);
}

.card__subtitle {
  font-size: var(--font-size-sm);
  color: var(--color-text-soft);
}

.card--interactive {
  transition: transform var(--transition-normal), box-shadow var(--transition-normal), border-color var(--transition-normal);
}

.card--interactive:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: rgba(59, 130, 246, 0.4);
}

/* Hero tag chips under CTAs */
.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.tag {
  display: inline-flex;
  align-items: center;
  padding: 0.25rem 0.7rem;
  border-radius: var(--radius-pill);
  background-color: rgba(226, 239, 255, 0.8);
  color: var(--color-text-soft);
  font-size: var(--font-size-xs);
  font-weight: 500;
}

/* ==========================================
   Hero Layout (central composition)
   ========================================== */
.hero {
  text-align: center;
}

.hero__label {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.25rem 0.75rem;
  border-radius: var(--radius-pill);
  background-color: rgba(255, 255, 255, 0.9);
  border: 1px solid rgba(148, 163, 184, 0.3);
  font-size: var(--font-size-xs);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-soft);
  margin-bottom: var(--space-3);
}

.hero__title {
  font-size: clamp(2.2rem, 4vw, 3rem);
  line-height: var(--line-height-tight);
  margin-bottom: var(--space-3);
}

.hero__subtitle {
  max-width: 36rem;
  margin-inline: auto;
  font-size: var(--font-size-lg);
  color: var(--color-text-soft);
  margin-bottom: var(--space-6);
}

.hero__actions {
  display: inline-flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  justify-content: center;
  margin-bottom: var(--space-4);
}

.hero__tags {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-2);
}

/* ==========================================
   Utilities specific to this project
   ========================================== */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-pill);
  font-size: var(--font-size-xs);
  font-weight: 500;
}

.badge--success {
  background-color: #dcfce7;
  color: #166534;
}

.badge--info {
  background-color: #e0f2fe;
  color: #075985;
}

.badge--neutral {
  background-color: #e5e7eb;
  color: #374151;
}

.text-pill {
  display: inline-flex;
  align-items: center;
  padding: 0.25rem 0.75rem;
  border-radius: var(--radius-pill);
  background-color: rgba(255, 255, 255, 0.9);
  font-size: var(--font-size-xs);
}

/* ==========================================
   Footer basics
   ========================================== */
.site-footer {
  border-top: 1px solid rgba(148, 163, 184, 0.25);
  background-color: rgba(248, 250, 252, 0.96);
  padding-block: var(--space-8);
  font-size: var(--font-size-sm);
}

.site-footer__top {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-6);
  justify-content: space-between;
  margin-bottom: var(--space-6);
}

.site-footer__bottom {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  justify-content: space-between;
  align-items: center;
  color: var(--color-gray-500);
}

.site-footer a {
  color: var(--color-text-soft);
}

.site-footer a:hover {
  color: var(--color-primary-strong);
}

@media (max-width: 768px) {
  .site-footer__top,
  .site-footer__bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}