/* ============================================================
   Vaccine Match — Style Sheet
   Design: medical-authoritative, warm navy + teal palette
   Fonts: Cabinet Grotesk (display) + Satoshi (body)
   ============================================================ */

/* --- Design Tokens --- */
:root, [data-theme="light"] {
  /* Type scale */
  --text-xs:   clamp(0.75rem,  0.7rem  + 0.25vw, 0.875rem);
  --text-sm:   clamp(0.875rem, 0.8rem  + 0.35vw, 1rem);
  --text-base: clamp(1rem,     0.95rem + 0.25vw, 1.125rem);
  --text-lg:   clamp(1.125rem, 1rem    + 0.75vw, 1.5rem);
  --text-xl:   clamp(1.5rem,   1.2rem  + 1.25vw, 2.25rem);

  /* Spacing */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-5:  1.25rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;

  /* Palette — Medical Navy + Teal */
  --color-bg:              #f4f6f9;
  --color-surface:         #ffffff;
  --color-surface-2:       #f8f9fb;
  --color-surface-offset:  #edf0f5;
  --color-divider:         #d8dde6;
  --color-border:          #c8cfd9;
  --color-text:            #1a2238;
  --color-text-muted:      #5a6579;
  --color-text-faint:      #9aa3b0;
  --color-text-inverse:    #f4f6f9;

  /* Primary: Teal */
  --color-primary:         #0b7a75;
  --color-primary-hover:   #085c58;
  --color-primary-active:  #064341;
  --color-primary-highlight: #c5e8e7;
  --color-primary-light:   #e3f4f3;

  /* Accent: Navy */
  --color-accent:          #1a3a6b;
  --color-accent-hover:    #122a52;
  --color-accent-light:    #e2e8f4;

  /* Disease card: warm amber */
  --color-disease:         #c45e00;
  --color-disease-bg:      #fff3e6;
  --color-disease-border:  #f5b87a;
  --color-disease-hover:   #a34c00;

  /* Vaccine card: teal */
  --color-vaccine:         #0b7a75;
  --color-vaccine-bg:      #e3f4f3;
  --color-vaccine-border:  #82ceca;
  --color-vaccine-hover:   #085c58;

  /* Success */
  --color-success:         #1a7c44;
  --color-success-light:   #e4f5ec;

  /* Radii */
  --radius-sm: 0.375rem;
  --radius-md: 0.625rem;
  --radius-lg: 1rem;
  --radius-xl: 1.25rem;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(26,34,56,0.07);
  --shadow-md: 0 4px 16px rgba(26,34,56,0.10);
  --shadow-lg: 0 12px 36px rgba(26,34,56,0.14);
  --shadow-card: 0 2px 8px rgba(26,34,56,0.09), 0 0 0 1px rgba(26,34,56,0.05);

  /* Transitions */
  --transition: 200ms cubic-bezier(0.16, 1, 0.3, 1);
  --transition-slow: 400ms cubic-bezier(0.16, 1, 0.3, 1);

  /* Fonts */
  --font-display: 'Cabinet Grotesk', 'Helvetica Neue', sans-serif;
  --font-body:    'Satoshi', 'Inter', sans-serif;

  /* Card flip */
  --card-w: clamp(130px, 16vw, 170px);
  --card-h: clamp(90px, 11vw, 118px);
}

[data-theme="dark"] {
  --color-bg:              #111827;
  --color-surface:         #1c2436;
  --color-surface-2:       #222d42;
  --color-surface-offset:  #19202f;
  --color-divider:         #2a3347;
  --color-border:          #334057;
  --color-text:            #dde3ef;
  --color-text-muted:      #7e8fa8;
  --color-text-faint:      #4a5568;
  --color-text-inverse:    #1a2238;
  --color-primary:         #2fc7bf;
  --color-primary-hover:   #5dd6d0;
  --color-primary-active:  #1aada6;
  --color-primary-highlight: #1d3f3e;
  --color-primary-light:   #193333;
  --color-accent:          #6a93d4;
  --color-accent-hover:    #8aadde;
  --color-accent-light:    #1c2a44;
  --color-disease:         #f0924a;
  --color-disease-bg:      #2a1e0f;
  --color-disease-border:  #7a4010;
  --color-disease-hover:   #f5a66e;
  --color-vaccine:         #2fc7bf;
  --color-vaccine-bg:      #132e2d;
  --color-vaccine-border:  #1a5552;
  --color-vaccine-hover:   #5dd6d0;
  --color-success:         #4ade80;
  --color-success-light:   #0f2e1c;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.25);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.35);
  --shadow-lg: 0 12px 36px rgba(0,0,0,0.45);
  --shadow-card: 0 2px 8px rgba(0,0,0,0.3), 0 0 0 1px rgba(255,255,255,0.04);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --color-bg:              #111827;
    --color-surface:         #1c2436;
    --color-surface-2:       #222d42;
    --color-surface-offset:  #19202f;
    --color-divider:         #2a3347;
    --color-border:          #334057;
    --color-text:            #dde3ef;
    --color-text-muted:      #7e8fa8;
    --color-text-faint:      #4a5568;
    --color-text-inverse:    #1a2238;
    --color-primary:         #2fc7bf;
    --color-primary-hover:   #5dd6d0;
    --color-primary-active:  #1aada6;
    --color-primary-highlight: #1d3f3e;
    --color-primary-light:   #193333;
    --color-accent:          #6a93d4;
    --color-accent-hover:    #8aadde;
    --color-accent-light:    #1c2a44;
    --color-disease:         #f0924a;
    --color-disease-bg:      #2a1e0f;
    --color-disease-border:  #7a4010;
    --color-disease-hover:   #f5a66e;
    --color-vaccine:         #2fc7bf;
    --color-vaccine-bg:      #132e2d;
    --color-vaccine-border:  #1a5552;
    --color-vaccine-hover:   #5dd6d0;
    --color-success:         #4ade80;
    --color-success-light:   #0f2e1c;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.25);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.35);
    --shadow-lg: 0 12px 36px rgba(0,0,0,0.45);
    --shadow-card: 0 2px 8px rgba(0,0,0,0.3), 0 0 0 1px rgba(255,255,255,0.04);
  }
}

/* --- Base Reset --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
}
body {
  min-height: 100dvh;
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.6;
  display: flex;
  flex-direction: column;
}
img, svg { display: block; max-width: 100%; }
button { cursor: pointer; border: none; background: none; font: inherit; color: inherit; }
a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, h4 { font-family: var(--font-display); line-height: 1.15; text-wrap: balance; }
p, li { text-wrap: pretty; }
:focus-visible { outline: 2px solid var(--color-primary); outline-offset: 3px; border-radius: var(--radius-sm); }
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
}

/* --- Header --- */
.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-divider);
  position: sticky;
  top: 0;
  z-index: 100;
}
.header-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: var(--space-3) var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.logo-group {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  color: var(--color-primary);
}
.logo-text {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: var(--text-lg);
  color: var(--color-text);
  letter-spacing: -0.02em;
}
.theme-toggle {
  width: 38px;
  height: 38px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-muted);
  transition: background var(--transition), color var(--transition);
}
.theme-toggle:hover {
  background: var(--color-surface-offset);
  color: var(--color-text);
}

/* --- Layout --- */
.main-content {
  flex: 1;
  max-width: 1100px;
  margin: 0 auto;
  width: 100%;
  padding: var(--space-8) var(--space-6);
}
.screen { width: 100%; }
.hidden { display: none !important; }

/* --- Start Screen --- */
.start-hero {
  max-width: 640px;
  margin: 0 auto;
  text-align: center;
  padding: var(--space-8) 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-6);
}
.start-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-1) var(--space-4);
  background: var(--color-primary-light);
  color: var(--color-primary);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}
.start-title {
  font-size: var(--text-xl);
  font-weight: 800;
  color: var(--color-text);
  letter-spacing: -0.02em;
  line-height: 1.1;
}
.start-desc {
  font-size: var(--text-base);
  color: var(--color-text-muted);
  max-width: 480px;
  line-height: 1.7;
}
.start-stats {
  display: flex;
  gap: var(--space-4);
  flex-wrap: wrap;
  justify-content: center;
}
.stat-pill {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-3) var(--space-5);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-1);
  min-width: 100px;
  box-shadow: var(--shadow-sm);
}
.stat-num {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 800;
  color: var(--color-primary);
}
.stat-label {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  text-align: center;
  font-weight: 500;
}
.start-hint {
  font-size: var(--text-sm);
  color: var(--color-text-faint);
  max-width: 400px;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: 700;
  font-family: var(--font-display);
  transition: background var(--transition), color var(--transition), box-shadow var(--transition), transform 80ms ease;
  cursor: pointer;
  border: none;
  text-decoration: none;
  white-space: nowrap;
}
.btn:active { transform: scale(0.97); }
.btn-primary {
  background: var(--color-primary);
  color: #fff;
  box-shadow: 0 2px 8px rgba(11,122,117,0.25);
}
.btn-primary:hover { background: var(--color-primary-hover); box-shadow: 0 4px 14px rgba(11,122,117,0.35); text-decoration: none; }
.btn-secondary {
  background: var(--color-surface);
  color: var(--color-text);
  border: 1.5px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}
.btn-secondary:hover { background: var(--color-surface-offset); text-decoration: none; }
.btn-lg {
  padding: var(--space-4) var(--space-10);
  font-size: var(--text-base);
  border-radius: var(--radius-lg);
}

/* --- Game Header --- */
.game-header {
  margin-bottom: var(--space-6);
}
.game-meta {
  display: flex;
  gap: var(--space-4);
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
}
.meta-item {
  background: var(--color-surface);
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-lg);
  padding: var(--space-3) var(--space-5);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  min-width: 90px;
  box-shadow: var(--shadow-sm);
}
.timer-item {
  border-color: var(--color-primary-highlight);
  background: var(--color-primary-light);
}
.meta-label {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-weight: 600;
}
.meta-value {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 800;
  color: var(--color-text);
  line-height: 1;
}
.timer-item .meta-value { color: var(--color-primary); }

/* --- Card Grid --- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-4);
  max-width: 780px;
  margin: 0 auto;
  align-items: stretch;
}

/* --- Flip Cards --- */
.flip-card {
  width: 100%;
  min-height: 140px;
  aspect-ratio: 4 / 3;
  perspective: 1000px;
  -webkit-perspective: 1000px;
  cursor: pointer;
  border-radius: var(--radius-lg);
  position: relative;
  display: block;
}

.flip-card:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 3px;
}

.flip-card-inner {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
  -webkit-transform-style: preserve-3d;
  transition: transform 0.5s cubic-bezier(0.16, 1, 0.3, 1);
  border-radius: var(--radius-lg);
}

.flip-card.flipped .flip-card-inner {
  transform: rotateY(180deg);
}

.flip-card-front,
.flip-card-back {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: var(--space-2);
  padding: var(--space-3);
  text-align: center;
  overflow: hidden;
}

/* Card back (face-down state) */
.flip-card-front {
  background: var(--color-accent);
  background-image: repeating-linear-gradient(
    45deg,
    transparent,
    transparent 10px,
    rgba(255,255,255,0.035) 10px,
    rgba(255,255,255,0.035) 20px
  );
  box-shadow: var(--shadow-card);
  border: 2px solid rgba(255,255,255,0.1);
}

.flip-card-front .card-back-icon {
  width: 32px;
  height: 32px;
  opacity: 0.6;
  color: #fff;
}

.flip-card-front .card-back-label {
  font-family: var(--font-display);
  font-size: var(--text-xs);
  font-weight: 700;
  color: rgba(255,255,255,0.5);
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

/* Card front (face-up state) */
.flip-card-back {
  transform: rotateY(180deg);
  box-shadow: var(--shadow-card);
}

.flip-card-back.disease-card {
  background: var(--color-disease-bg);
  border: 2px solid var(--color-disease-border);
}

.flip-card-back.vaccine-card {
  background: var(--color-vaccine-bg);
  border: 2px solid var(--color-vaccine-border);
}

/* Hover state — only on unflipped, unmatched cards */
.flip-card:not(.flipped):not(.matched):hover .flip-card-front {
  background: var(--color-primary);
  border-color: var(--color-primary-hover);
}

.flip-card:not(.flipped):not(.matched):hover .flip-card-front .card-back-icon {
  opacity: 1;
}

/* Matched state */
.flip-card.matched .flip-card-back.disease-card,
.flip-card.matched .flip-card-back.vaccine-card {
  background: var(--color-success-light);
  border-color: var(--color-success);
}

.flip-card.matched .card-type-badge {
  background: rgba(26,124,68,0.15);
  color: var(--color-success);
}

/* Mismatch animation */
@keyframes shake {
  0%, 100% { transform: rotateY(180deg) translateX(0); }
  20% { transform: rotateY(180deg) translateX(-6px); }
  40% { transform: rotateY(180deg) translateX(6px); }
  60% { transform: rotateY(180deg) translateX(-4px); }
  80% { transform: rotateY(180deg) translateX(4px); }
}

.flip-card.mismatch .flip-card-inner {
  animation: shake 0.45s ease;
}

/* --- Modal --- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(17,24,39,0.65);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-4);
  animation: fadeIn 0.25s ease;
}
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
.modal-card {
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  padding: var(--space-8);
  max-width: 560px;
  width: 100%;
  max-height: 90dvh;
  overflow-y: auto;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--color-divider);
  animation: slideUp 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}
@keyframes slideUp { from { opacity: 0; transform: translateY(20px); } to { opacity: 1; transform: translateY(0); } }
.modal-match-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  background: var(--color-success-light);
  color: var(--color-success);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: 700;
  align-self: flex-start;
}
.modal-title {
  font-size: var(--text-lg);
  font-weight: 800;
  color: var(--color-text);
  letter-spacing: -0.01em;
}
.modal-sections {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}
.modal-section {
  background: var(--color-surface-2);
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-lg);
  padding: var(--space-4) var(--space-5);
}
.modal-section-title {
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-primary);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: var(--space-3);
}
.modal-section-content {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.7;
}
.modal-section-content strong {
  color: var(--color-text);
  font-weight: 600;
}
.modal-continue-btn {
  width: 100%;
  padding: var(--space-4);
  font-size: var(--text-base);
  border-radius: var(--radius-lg);
}

/* --- Summary Screen --- */
.summary-card {
  max-width: 600px;
  margin: 0 auto;
  padding: var(--space-8) 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-8);
}
.summary-hero { text-align: center; display: flex; flex-direction: column; align-items: center; gap: var(--space-4); }
.summary-trophy {
  width: 80px;
  height: 80px;
  background: var(--color-primary-light);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-primary);
}
.summary-title {
  font-size: var(--text-xl);
  font-weight: 800;
  color: var(--color-text);
  letter-spacing: -0.02em;
}
.summary-subtitle {
  font-size: var(--text-base);
  color: var(--color-text-muted);
}
.summary-stats {
  display: flex;
  gap: var(--space-4);
  flex-wrap: wrap;
  justify-content: center;
  width: 100%;
}
.summary-stat {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-4) var(--space-6);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-1);
  flex: 1;
  min-width: 130px;
  box-shadow: var(--shadow-sm);
}
.summary-stat-label {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-weight: 600;
}
.summary-stat-value {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 800;
  color: var(--color-primary);
}
.summary-pairs {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}
.summary-pair-row {
  background: var(--color-surface);
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-lg);
  padding: var(--space-4) var(--space-5);
  display: flex;
  align-items: center;
  gap: var(--space-3);
  box-shadow: var(--shadow-sm);
}
.pair-match-icon {
  width: 28px;
  height: 28px;
  background: var(--color-success-light);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-success);
  flex-shrink: 0;
}
.pair-names {
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.pair-disease {
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-disease);
}
.pair-vaccine {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
}
.summary-learn {
  background: var(--color-accent-light);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  text-align: center;
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-4);
}
.summary-learn-text {
  font-size: var(--text-base);
  color: var(--color-text);
  font-weight: 500;
}

/* --- Footer --- */
.site-footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-divider);
  padding: var(--space-6);
}
.footer-inner {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  align-items: center;
  text-align: center;
}
.footer-sources {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  line-height: 1.8;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1) var(--space-2);
  justify-content: center;
  align-items: center;
}
.footer-sources a { color: var(--color-text-muted); }
.footer-sources a:hover { color: var(--color-primary); }
.sep { color: var(--color-text-faint); }
.footer-credit {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}
.footer-credit a { color: var(--color-text-faint); }
.footer-credit a:hover { color: var(--color-text-muted); }

/* --- Responsive --- */
@media (max-width: 680px) {
  .card-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: var(--space-3);
  }

  .flip-card {
    min-height: 120px;
    aspect-ratio: 3 / 2;
  }
}

@media (max-width: 440px) {
  .card-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: var(--space-2);
    grid-auto-rows: 120px;
  }

  .flip-card {
    min-height: 120px;
    height: 120px;
    aspect-ratio: auto;
  }
}