:root {
  /* Colors */
  --clr-primary-teal: hsl(179, 62%, 43%);
  --clr-primary-teal-light: hsl(179, 62%, 48%); /* Lighter variation for layout grid */
  --clr-primary-green: hsl(71, 73%, 54%);
  --clr-primary-green-hover: hsl(71, 73%, 60%);
  
  --clr-neutral-light-gray: hsl(204, 43%, 93%);
  --clr-neutral-gray-blue: hsl(218, 22%, 67%);
  --clr-neutral-white: hsl(0, 0%, 100%);

  /* Typography */
  --ff-sans: 'Karla', sans-serif;
  --fs-body: 1rem; /* 16px */
  
  /* Shadows & Radius */
  --radius-main: 8px;
  --shadow-card: 0 10px 30px rgba(0, 0, 0, 0.1);
}

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

body {
  font-family: var(--ff-sans);
  font-size: var(--fs-body);
  line-height: 1.6;
  background-color: var(--clr-neutral-light-gray);
  color: var(--clr-neutral-gray-blue);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 1.5rem;
}

/* Accessibility: Screen Reader Only helper */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

/* Reset list defaults for role="list" layouts */
ul[role="list"] {
  list-style: none;
}

.card-container {
  width: 100%;
  max-width: 635px;
  margin-block: auto;
}

.price-card {
  background-color: var(--clr-neutral-white);
  border-radius: var(--radius-main);
  overflow: hidden;
  box-shadow: var(--shadow-card);
  display: grid;
  grid-template-columns: 1fr;
}

/* Shared Padding System via Logical Properties */
.price-card__intro,
.price-card__subscription,
.price-card__features {
  padding: 1.5rem;
}

/* --- Intro Section Styles --- */
.price-card__intro {
  background-color: var(--clr-neutral-white);
}

.price-card__title {
  color: var(--clr-primary-teal);
  font-size: 1.35rem;
  font-weight: 700;
  margin-block-end: 1rem;
}

.price-card__guarantee {
  color: var(--clr-primary-green);
  font-weight: 700;
  font-size: 0.95rem;
  margin-block-end: 0.75rem;
}

.price-card__description {
  font-size: 0.875rem;
  line-height: 1.7;
}

/* --- Subscription Section Styles --- */
.price-card__subscription {
  background-color: var(--clr-primary-teal);
  color: var(--clr-neutral-white);
}

.price-card__subtitle {
  font-size: 1.1rem;
  font-weight: 700;
  margin-block-end: 1rem;
}

.price-card__price-container {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-block-end: 0.5rem;
}

.price-card__amount {
  font-size: 2rem;
  font-weight: 700;
}

.price-card__frequency {
  color: rgba(255, 255, 255, 0.6);
  font-size: 0.95rem;
}

.price-card__access {
  font-size: 0.95rem;
  margin-block-end: 1.75rem;
}

/* Action Call-to-action Element */
.price-card__cta {
  display: block;
  text-align: center;
  background-color: var(--clr-primary-green);
  color: var(--clr-neutral-white);
  text-decoration: none;
  font-weight: 700;
  padding-block: 0.85rem;
  border-radius: 5px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.15);
  transition: background-color 0.2s ease, transform 0.1s ease;
}

.price-card__cta:hover {
  background-color: var(--clr-primary-green-hover);
}

.price-card__cta:focus-visible {
  outline: 3px solid var(--clr-neutral-white);
  outline-offset: 2px;
}

.price-card__cta:active {
  transform: scale(0.98);
}

/* --- Features Section Styles --- */
.price-card__features {
  background-color: var(--clr-primary-teal-light);
  color: var(--clr-neutral-white);
}

.price-card__list {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.price-card__list-item {
  font-size: 0.85rem;
  color: rgba(255, 255, 255, 0.85);
}

/* Responsive desktop */
@media (min-width: 600px) {
  .price-card {
    grid-template-columns: 1fr 1fr;
  }
  
  .price-card__intro {
    grid-column: span 2;
    padding: 2.5rem;
  }

  .price-card__subscription,
  .price-card__features {
    padding: 2.5rem;
  }
}

/* Attribution Footer */
.attribution {
  font-size: 0.6875rem;
  text-align: center;
  margin-block-start: 2rem;
}

.attribution a {
  color: hsl(228, 45%, 44%);
  font-weight: 700;
  text-decoration: none;
}

.attribution a:hover {
  text-decoration: underline;
}