/* physchem-interactives shared site styles */

:root {
  --color-bg: #f7f8fa;
  --color-surface: #ffffff;
  --color-text: #1b1f23;
  --color-muted: #55606b;
  --color-primary: #0b5fa5;
  --color-primary-dark: #08426f;
  --color-border: #d7dce1;
  --focus-ring: 3px solid #ffbf47;
  --radius: 0.5rem;
  --max-width: 64rem;
}

* {
  box-sizing: border-box;
}

html {
  font-size: 100%;
}

body {
  margin: 0;
  font-family: "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.5;
}

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

a:hover,
a:focus {
  color: var(--color-primary-dark);
}

a:focus-visible,
button:focus-visible,
input:focus-visible {
  outline: var(--focus-ring);
  outline-offset: 2px;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--color-primary-dark);
  color: #fff;
  padding: 0.75rem 1rem;
  z-index: 100;
  border-radius: 0 0 var(--radius) 0;
}

.skip-link:focus {
  left: 0;
}

.site-header {
  background-color: var(--color-primary-dark);
  color: #fff;
  padding: 1.5rem 1rem;
}

.site-header .container {
  max-width: var(--max-width);
  margin: 0 auto;
}

.site-header h1 {
  margin: 0 0 0.25rem 0;
  font-size: clamp(1.5rem, 4vw, 2.25rem);
}

.site-header p {
  margin: 0;
  color: #d9e8f5;
}

.site-main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1.5rem 1rem 3rem;
}

.topic-section {
  margin-bottom: 2.5rem;
}

.topic-section h2 {
  font-size: 1.5rem;
  border-bottom: 2px solid var(--color-border);
  padding-bottom: 0.5rem;
  margin-bottom: 1rem;
}

.activity-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(15rem, 1fr));
  gap: 1rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.activity-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1rem;
  display: flex;
  flex-direction: column;
  height: 100%;
}

.activity-card h3 {
  margin: 0 0 0.5rem 0;
  font-size: 1.1rem;
}

.activity-card p {
  margin: 0 0 1rem 0;
  color: var(--color-muted);
  flex-grow: 1;
}

.activity-card a.button-link {
  display: inline-block;
  align-self: flex-start;
  background-color: var(--color-primary);
  color: #fff;
  text-decoration: none;
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
  font-weight: 600;
}

.activity-card a.button-link:hover,
.activity-card a.button-link:focus {
  background-color: var(--color-primary-dark);
}

.site-footer {
  text-align: center;
  padding: 1.5rem 1rem;
  color: var(--color-muted);
  font-size: 0.9rem;
}

.activity-page main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1.5rem 1rem 3rem;
}

.breadcrumb {
  font-size: 0.9rem;
  margin-bottom: 1rem;
}

.placeholder-note {
  background-color: #fff8e5;
  border: 1px solid #f0d585;
  border-radius: var(--radius);
  padding: 1rem;
}