/*
  UIUC++ SRSE — theme (customize via :root variables)
  Illinois-inspired palette: https://brand.illinois.edu/
*/

:root {
  /* Brand */
  --color-illini-blue: #13294b;
  --color-illini-orange: #ff552e;
  --color-illini-blue-light: #1a3a6e;
  --color-illini-orange-muted: #e04a28;

  /* Surfaces */
  --color-bg: #f5f7fa;
  --color-bg-card: #ffffff;
  --color-bg-hero: linear-gradient(
    145deg,
    var(--color-illini-blue) 0%,
    var(--color-illini-blue-light) 55%,
    #0d1f3a 100%
  );
  --color-border: #d1d9e6;
  --color-border-accent: rgba(255, 85, 46, 0.35);

  /* Text */
  --color-text: #1a1a1a;
  --color-text-muted: #4a5568;
  --color-text-on-dark: #f7fafc;
  --color-text-on-dark-muted: #cbd5e0;

  /* Links & focus */
  --color-link: #0b4f9c;
  --color-link-hover: var(--color-illini-orange);
  --color-focus-ring: var(--color-illini-orange);

  /* Components */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --shadow-sm: 0 1px 3px rgba(19, 41, 75, 0.08);
  --shadow-md: 0 8px 24px rgba(19, 41, 75, 0.12);
  --max-width: 52rem;
  --max-width-wide: 72rem;
  --space-section: 3.5rem;
  --font-sans: "Source Sans 3", "Segoe UI", system-ui, sans-serif;
  --font-heading: var(--font-sans);
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
}

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

a {
  color: var(--color-link);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

a:hover {
  color: var(--color-link-hover);
}

.skip-link {
  position: absolute;
  left: -9999px;
  z-index: 100;
  padding: 0.75rem 1rem;
  background: var(--color-illini-orange);
  color: #fff;
  font-weight: 600;
}

.skip-link:focus {
  left: 1rem;
  top: 1rem;
}

.site-header {
  background: var(--color-illini-blue);
  color: var(--color-text-on-dark);
  border-bottom: 4px solid var(--color-illini-orange);
}

.site-header__inner {
  max-width: var(--max-width-wide);
  margin: 0 auto;
  padding: 1rem 1.25rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.site-title {
  margin: 0;
  font-size: 1.125rem;
  font-weight: 700;
  font-family: var(--font-heading);
  letter-spacing: 0.02em;
}

.site-title a {
  color: inherit;
  text-decoration: none;
}

.site-title a:hover {
  color: var(--color-text-on-dark-muted);
}

.site-nav ul {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.25rem;
}

.site-nav a {
  color: var(--color-text-on-dark-muted);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
}

.site-nav a:hover {
  color: #fff;
}

.hero {
  background: var(--color-bg-hero);
  color: var(--color-text-on-dark);
  padding: 2.75rem 1.25rem 3rem;
}

.hero__inner {
  max-width: var(--max-width-wide);
  margin: 0 auto;
}

.hero__badge {
  display: inline-block;
  margin: 0 0 0.75rem;
  padding: 0.35rem 0.75rem;
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  background: rgba(255, 85, 46, 0.25);
  border: 1px solid rgba(255, 85, 46, 0.5);
  border-radius: var(--radius-sm);
}

.hero h1 {
  margin: 0 0 0.75rem;
  font-size: clamp(1.75rem, 4vw, 2.35rem);
  font-weight: 700;
  line-height: 1.2;
  font-family: var(--font-heading);
}

.hero__lead {
  margin: 0 0 1.5rem;
  max-width: 42rem;
  font-size: 1.125rem;
  color: var(--color-text-on-dark-muted);
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: center;
}

/* Deadline callout */
.deadline-strip {
  background: #fff8f5;
  border-bottom: 1px solid var(--color-border-accent);
  padding: 1rem 1.25rem;
}

.deadline-strip__inner {
  max-width: var(--max-width-wide);
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  align-items: flex-start;
  gap: 0.75rem 1.5rem;
}

.deadline-strip strong {
  color: var(--color-illini-blue);
}

.deadline-strip p {
  margin: 0;
  flex: 1;
  min-width: min(100%, 16rem);
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.85rem 1.5rem;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 700;
  text-align: center;
  text-decoration: none;
  border-radius: var(--radius-md);
  border: 2px solid transparent;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

.btn--primary {
  background: var(--color-illini-orange);
  color: #fff;
  border-color: var(--color-illini-orange);
}

.btn--primary:hover {
  background: var(--color-illini-orange-muted);
  border-color: var(--color-illini-orange-muted);
  color: #fff;
}

.btn--secondary {
  background: transparent;
  color: var(--color-text-on-dark);
  border-color: rgba(255, 255, 255, 0.45);
}

.btn--secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
}

/* Sections */
main > section {
  padding: var(--space-section) 1.25rem;
}

main > section:nth-child(even) {
  background: var(--color-bg-card);
  box-shadow: var(--shadow-sm);
}

.section__inner {
  max-width: var(--max-width);
  margin: 0 auto;
}

.section__title {
  margin: 0 0 1rem;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-illini-blue);
  font-family: var(--font-heading);
  padding-bottom: 0.5rem;
  border-bottom: 3px solid var(--color-illini-orange);
  display: inline-block;
}

.section__intro {
  margin: 0 0 1.25rem;
  color: var(--color-text-muted);
}

.callout {
  margin: 1.5rem 0 0;
  padding: 1rem 1.25rem;
  background: #eef4fc;
  border-left: 4px solid var(--color-illini-blue);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.callout p {
  margin: 0;
}

/* Faculty list */
.faculty-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(17rem, 1fr));
  gap: 1rem;
  margin: 1.5rem 0 0;
  padding: 0;
  list-style: none;
}

.faculty-grid li {
  margin: 0;
  padding: 1rem 1.1rem;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}

.faculty-grid__name {
  display: block;
  margin-bottom: 0.25rem;
  color: var(--color-illini-blue);
  font-weight: 700;
  text-decoration: none;
}

.faculty-grid__name:hover {
  color: var(--color-link-hover);
  text-decoration: underline;
}

.faculty-grid__name strong {
  font-weight: 700;
}

.faculty-grid span {
  font-size: 0.95rem;
  color: var(--color-text-muted);
}

/* Topic tags */
.topic-list {
  margin: 1rem 0 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.topic-list li {
  margin: 0;
  padding: 0.35rem 0.75rem;
  font-size: 0.9rem;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
}

/* Lists */
.content-list {
  margin: 0.75rem 0 0;
  padding-left: 1.35rem;
}

.content-list li {
  margin-bottom: 0.35rem;
}

.link-list {
  margin: 1rem 0 0;
  padding: 0;
  list-style: none;
}

.link-list li {
  margin-bottom: 0.5rem;
  padding-left: 0;
}

/* Application CTA block */
.apply-block {
  margin-top: 1.5rem;
  padding: 1.75rem;
  background: var(--color-illini-blue);
  color: var(--color-text-on-dark);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  text-align: center;
}

.apply-block p {
  margin: 0 0 1rem;
  font-size: 1.05rem;
}

.apply-block .btn--primary {
  font-size: 1.05rem;
  padding: 1rem 2rem;
}

.apply-block .note {
  margin: 1rem 0 0;
  font-size: 0.9rem;
  color: var(--color-text-on-dark-muted);
}

/* Footer */
.site-footer {
  padding: 2rem 1.25rem;
  background: var(--color-illini-blue);
  color: var(--color-text-on-dark-muted);
  font-size: 0.9rem;
}

.site-footer__inner {
  max-width: var(--max-width-wide);
  margin: 0 auto;
}

.site-footer a {
  color: #fff;
}

.site-footer p {
  margin: 0 0 0.5rem;
}