:root {
  /* Light theme variables */
  --bg-color: #f7f9fa;
  --text-color: #111111;
  --card-bg: #fff;
  --card-border: #e0e0e0;
  --header-bg: #22304a;
  --search-bg: #f0f2f5;
  --search-text: #222831;
  --button-hover: #e5e5e5;
  --accent-color: #2563eb;
  --accent-bg: #eaf1fb;
  --shadow: 0 4px 24px rgba(34, 48, 74, 0.1);
  --radius: 18px;
  --font-main: "Outfit", "Segoe UI", "Roboto", "Arial", sans-serif;
  --font-size-base: 1.08rem;
  --font-size-lg: 1.25rem;
  --font-size-sm: 0.97rem;
  --line-height: 1.6;
}

/* Dark theme variables */
.dark-mode {
  --bg-color: #181c23;
  --text-color: #f3f6fa;
  --card-bg: #232a36;
  --card-border: #2d3748;
  --header-bg: #1a2233;
  --search-bg: #232a36;
  --search-text: #f3f6fa;
  --button-hover: #2d3748;
  --accent-color: #60a5fa;
  --accent-bg: #1e293b;
  --shadow: 0 4px 24px rgba(16, 24, 39, 0.18);
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  font-family: var(--font-main);
  font-size: var(--font-size-base);
  line-height: var(--line-height);
  transition: background-color 0.3s, color 0.3s;
}

header,
footer {
  background-color: var(--header-bg) !important;
  color: var(--text-color);
  font-family: var(--font-main);
}

.cards {
  background-color: var(--card-bg);
  border: 1.5px solid var(--card-border);
  box-shadow: var(--shadow);
  color: var(--text-color);
  border-radius: var(--radius);
  transition: background-color 0.3s, border-color 0.3s, box-shadow 0.3s;
  contain: content;
  will-change: transform;
}

.cards:hover {
  box-shadow: 0 8px 32px rgba(34, 48, 74, 0.16);
  transform: translateY(-4px) scale(1.03);
}

.cards h2,
.cards h3,
.cards p,
.cards .study-links a {
  color: var(--text-color);
}

.cards h2 {
  font-size: var(--font-size-lg);
}

.cards h3 {
  font-size: var(--font-size-base);
  color: var(--text-color);
  opacity: 0.85;
}

.cards p {
  font-size: var(--font-size-sm);
  color: var(--text-color);
  margin-bottom: 0.75em;
}

.cards .card-links {
  display: flex;
  gap: 0.5em;
  margin-bottom: 0.75em;
}

.cards .card-links a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-bg);
  color: var(--accent-color);
  border-radius: 50%;
  width: 2.2em;
  height: 2.2em;
  font-size: 1.2em;
  transition: background 0.2s, color 0.2s;
  box-shadow: none;
}

.cards .card-links a:hover {
  background: var(--accent-color);
  color: #fff;
}

.cards .study-links {
  display: flex;
  flex-direction: column;
  gap: 0.5em;
  margin-top: 0.5em;
}

.cards .study-links a {
  background: #f7f9fa;
  border: 1px solid #e0e0e0;
  color: #111111;
  border-radius: var(--radius);
  padding: 0.5em 1em;
  font-size: var(--font-size-sm);
  font-weight: 500;
  text-align: center;
  text-decoration: none;
  transition: background 0.2s, color 0.2s;
}

.cards .study-links a:hover {
  background: var(--accent-color);
  color: #fff;
}

.cards .card-date {
  display: flex;
  align-items: center;
  gap: 0.4em;
  background: var(--accent-bg);
  color: var(--accent-color);
  border-radius: 1em;
  font-size: 0.95em;
  padding: 0.2em 0.9em;
  margin-bottom: 0.7em;
  font-weight: 500;
}

/* Card social link button hover/focus */
.cards .card-social-links a {
  transition: background 0.25s, color 0.25s, box-shadow 0.25s, transform 0.25s;
  box-shadow: none;
  outline: none;
}
.cards .card-social-links a:hover,
.cards .card-social-links a:focus {
  background: var(--accent-color);
  color: #fff;
  box-shadow: 0 2px 8px rgba(34, 48, 74, 0.1);
  transform: translateY(-2px) scale(1.07);
}
.dark-mode .cards .card-social-links a:hover,
.dark-mode .cards .card-social-links a:focus {
  background: var(--accent-color);
  color: #fff;
  box-shadow: 0 2px 8px rgba(16, 24, 39, 0.18);
}

/* Card study link button hover/focus */
.cards .card-study-links a {
  transition: background 0.25s, color 0.25s, box-shadow 0.25s, transform 0.25s;
  outline: none;
}
.cards .card-study-links a:hover,
.cards .card-study-links a:focus {
  background: var(--accent-color);
  color: #fff;
  box-shadow: 0 2px 8px rgba(34, 48, 74, 0.1);
  transform: translateY(-2px) scale(1.03);
}
.dark-mode .cards .card-study-links a:hover,
.dark-mode .cards .card-study-links a:focus {
  background: var(--accent-color);
  color: #fff;
  box-shadow: 0 2px 8px rgba(16, 24, 39, 0.18);
}

#searchInput {
  background-color: var(--search-bg);
  color: var(--search-text);
  border-radius: var(--radius);
  border: 1.5px solid var(--card-border);
  padding: 0.6em 1.2em;
  font-size: var(--font-size-base);
  margin: 0.5em 0;
  transition: background-color 0.3s, color 0.3s, border-color 0.3s;
}

#searchInput:focus {
  outline: 2px solid var(--accent-color);
  border-color: var(--accent-color);
}

.hidden {
  display: none !important;
}

/* Navbar tab switcher styles */
#viewToggle {
  border-radius: 0.5rem;
  overflow: hidden;
  border: 1.5px solid var(--card-border);
  background: var(--header-bg);
}
#viewToggle button {
  background: transparent;
  color: var(--text-color);
  border: none;
  outline: none;
  font-weight: 500;
  transition: background 0.25s, color 0.25s, box-shadow 0.25s, transform 0.25s;
  position: relative;
  z-index: 1;
}
#viewToggle button:hover {
  background: var(--button-hover);
  color: var(--accent-color);
  box-shadow: 0 2px 8px rgba(34, 48, 74, 0.1);
  transform: translateY(-2px) scale(1.04);
}
.dark-mode #viewToggle button:hover {
  background: #2d3748;
  color: var(--accent-color);
  box-shadow: 0 2px 8px rgba(16, 24, 39, 0.18);
}
#viewToggle button[aria-pressed="true"],
#viewToggle button.bg-blue-600,
#viewToggle button.dark\:bg-blue-500 {
  background: var(--accent-color);
  color: #fff;
}
#viewToggle button[aria-pressed="false"] {
  background: transparent;
  color: var(--text-color);
}
#viewToggle .material-icons {
  font-size: 1.3em;
}

/* --- List View Card Styles --- */
.card-list-item {
  background: var(--card-bg);
  border: 1.5px solid var(--card-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  transition: background 0.3s, border-color 0.3s, box-shadow 0.3s,
    transform 0.3s;
  align-items: flex-start;
  min-height: 110px;
  contain: content;
  will-change: transform;
}
.card-list-item:hover {
  box-shadow: 0 8px 32px rgba(34, 48, 74, 0.16);
  transform: translateY(-2px) scale(1.01);
}
.card-list-item .card-title {
  font-size: 1.1rem;
  font-weight: 700;
  margin-right: 0.5em;
}
.card-list-item .card-subtitle {
  font-size: 0.98rem;
  opacity: 0.8;
  font-weight: 500;
}
.card-list-item .card-date {
  font-size: 0.85rem;
  margin-bottom: 0.5em;
  padding: 0.2em 0.7em;
}
.card-list-item .card-social-links a {
  border-radius: 0.5em;
  font-size: 1.1em;
  padding: 0.5em;
  background: var(--accent-bg);
  color: var(--accent-color);
  transition: background 0.2s, color 0.2s, box-shadow 0.2s, transform 0.2s;
}
.card-list-item .card-social-links a:hover,
.card-list-item .card-social-links a:focus {
  background: var(--accent-color);
  color: #fff;
  box-shadow: 0 2px 8px rgba(34, 48, 74, 0.1);
  transform: translateY(-2px) scale(1.07);
}
.card-list-item .card-study-links a {
  font-size: 0.95rem;
  padding: 0.4em 0.8em;
}

/* --- Accordion Styles --- */
.accordion-toggle {
  background: var(--accent-bg);
  color: var(--accent-color);
  border: none;
  cursor: pointer;
  font-size: 0.98rem;
  font-weight: 600;
  margin: 0.2em 0 0.2em 0;
  transition: background 0.2s, color 0.2s, box-shadow 0.2s;
  outline: none;
  box-shadow: none;
}
.accordion-toggle:hover,
.accordion-toggle:focus {
  background: var(--accent-color);
  color: #fff;
  box-shadow: 0 2px 8px rgba(34, 48, 74, 0.1);
}

.accordion-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  will-change: max-height;
}
.card-list-item .accordion-content[aria-hidden="false"] {
  /* When expanded, allow content to show */
  overflow: visible;
}

/* Accordion chevron indicator */
.accordion-toggle .chevron {
  display: inline-block;
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  vertical-align: middle;
  margin-left: 0.2em;
}

/* Accordion expanded state highlight */
.card-list-item .accordion-content.expanded {
  background: linear-gradient(
    90deg,
    var(--accent-bg) 0 10%,
    var(--card-bg) 100%
  );
  border-left: 3px solid var(--accent-color);
  box-shadow: 0 2px 12px rgba(34, 48, 74, 0.07);
}

.card-list-item .accordion-content {
  border-top: 1.5px solid var(--card-border);
  margin-top: -1px;
}

.card-list-item .accordion-content .card-text {
  margin-bottom: 0.5em;
}

.card-list-item .accordion-content .card-study-links {
  margin-top: 0.5em;
}

@media (max-width: 640px) {
  nav {
    flex-direction: column !important;
    align-items: stretch !important;
    gap: 0.5rem !important;
  }
  nav > h3 {
    width: 100%;
    text-align: center;
    margin-bottom: 0.25rem;
  }
  nav > div {
    flex-direction: column !important;
    width: 100%;
    gap: 0.5rem !important;
  }
  #viewToggle {
    width: 100%;
    justify-content: center;
    margin-bottom: 0.25rem;
  }
  #searchInput {
    width: 100%;
    margin-left: 0 !important;
    margin-bottom: 0.25rem;
  }
  #themeToggleBtn {
    margin-left: 0 !important;
    align-self: center;
  }
}

@media (max-width: 600px) {
  .cards {
    padding: 1.1em !important;
  }
  .cards h2 {
    font-size: 1.08rem;
  }
  .card-list-item {
    flex-direction: column !important;
    align-items: stretch !important;
    padding: 1em !important;
  }
  .card-list-item .card-title {
    font-size: 1rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  * {
    transition: none !important;
  }
}