:root {
  --font-heading: "Playfair Display", "Noto Serif SC", serif;
  --font-body: "Source Sans Pro", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: "SF Mono", "Monaco", "Consolas", monospace;

  --color-bg-primary: #f7efe6;
  --color-bg-secondary: #fffaf4;
  --color-bg-dark: #2d2a26;
  --color-text-primary: #2d2a26;
  --color-text-secondary: #7a6b5a;
  --color-text-inverse: #fffaf4;
  --color-border: #e7d8c7;
  --color-brand: #8b5d33;
  --color-stamp: #b15a44;

  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  --space-xs: 6px;
  --space-sm: 10px;
  --space-md: 14px;
  --space-lg: 20px;
  --space-xl: 28px;
  --space-2xl: 36px;
}

* { box-sizing: border-box; }

body {
  font-family: var(--font-body);
  background: var(--color-bg-primary);
  color: var(--color-text-primary);
  min-height: 100vh;
  margin: 0;
  -webkit-font-smoothing: antialiased;
}

.shell {
  width: min(920px, 100%);
  min-height: 100vh;
  margin: 0 auto;
  padding: var(--space-md);
  display: grid;
  place-items: center;
}

@media (min-width: 640px) {
  body {
    background: #ede5d8;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--space-xl);
  }

  .shell {
    min-height: auto;
    padding: 0;
  }
}

@media (min-width: 1024px) {
  body {
    background: #e0d4c3;
    background-image:
      radial-gradient(ellipse at 30% 40%, rgba(237,148,64,0.08) 0%, transparent 60%),
      radial-gradient(ellipse at 70% 70%, rgba(139,93,51,0.06) 0%, transparent 60%);
  }
}

.envelope,
.letter {
  width: 100%;
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: 0 16px 48px rgba(45, 42, 38, 0.08);
}

.envelope {
  max-width: 560px;
  padding: var(--space-xl);
}

@media (min-width: 640px) {
  .envelope {
    border-radius: var(--radius-xl);
    padding: var(--space-2xl);
  }
}

.header {
  text-align: center;
  margin-bottom: var(--space-xl);
}

.eyebrow {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 2px;
  color: var(--color-brand);
  margin: 0 0 var(--space-sm);
}

.header h1 {
  margin: 0;
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--color-text-primary);
}

@media (min-width: 640px) {
  .header h1 { font-size: 1.8rem; }
}

.envelope-card {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  margin-bottom: var(--space-xl);
  position: relative;
}

@media (min-width: 640px) {
  .envelope-card {
    border: 2px dashed var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--space-xl);
  }

  .envelope-card::before {
    content: "";
    position: absolute;
    top: -10px;
    right: 20px;
    width: 48px;
    height: 56px;
    background: var(--color-stamp);
    border-radius: var(--radius-sm);
    transform: rotate(6deg);
    opacity: 0.85;
  }
}

.envelope-icon {
  width: 64px;
  height: 64px;
  background: var(--color-bg-primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--space-md);
}

.envelope-icon svg {
  width: 32px;
  height: 32px;
  color: var(--color-brand);
}

.letter-title-label {
  margin: 0 0 var(--space-xs);
  text-align: center;
  font-size: 0.75rem;
  color: var(--color-text-secondary);
}

.letter-title-value {
  margin: 0 0 var(--space-lg);
  text-align: center;
  font-family: var(--font-heading);
  font-size: 1.35rem;
  font-weight: 600;
  line-height: 1.3;
  color: var(--color-text-primary);
}

.participant-info {
  text-align: center;
  margin-bottom: var(--space-lg);
}

.participant-arrow {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-md);
  font-size: 1rem;
  color: var(--color-text-primary);
  flex-wrap: wrap;
}

.participant-name { font-weight: 600; }

.participant-arrow svg {
  width: 18px;
  height: 18px;
  color: var(--color-brand);
  flex-shrink: 0;
}

.unlock-date {
  text-align: center;
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  margin: 0;
  padding-top: var(--space-md);
  border-top: 1px dashed var(--color-border);
}

.unlock-date strong { color: var(--color-text-primary); }

.countdown-section {
  background: var(--color-bg-dark);
  border-radius: var(--radius-xl);
  padding: var(--space-xl);
  margin-bottom: var(--space-xl);
}

@media (min-width: 640px) {
  .countdown-section {
    border-radius: var(--radius-md);
    padding: var(--space-xl) var(--space-2xl);
  }
}

.countdown-label {
  text-align: center;
  font-size: 0.875rem;
  color: rgba(255, 250, 244, 0.6);
  margin: 0 0 var(--space-lg);
}

.countdown-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-sm);
}

@media (min-width: 640px) {
  .countdown-grid { gap: var(--space-md); }
}

.countdown-item { text-align: center; }

.countdown-value {
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-text-inverse);
  background: rgba(255, 250, 244, 0.1);
  border-radius: var(--radius-md);
  padding: var(--space-sm);
  margin-bottom: var(--space-sm);
  line-height: 1;
  font-variant-numeric: tabular-nums;
}

@media (min-width: 640px) {
  .countdown-value {
    font-size: 2.5rem;
    padding: var(--space-md);
  }
}

.countdown-unit {
  font-size: 0.7rem;
  color: rgba(255, 250, 244, 0.5);
  letter-spacing: 1px;
}

.hint {
  text-align: center;
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  font-style: italic;
  margin: 0 0 var(--space-xl);
}

.footer {
  text-align: center;
  border-top: 1px solid var(--color-border);
  padding-top: var(--space-lg);
}

.footer-brand {
  margin: 0;
  font-family: var(--font-heading);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-brand);
}

.footer-tagline {
  margin: var(--space-xs) 0 0;
  font-size: 0.75rem;
  color: var(--color-text-secondary);
}

.letter {
  overflow: hidden;
}

.letterHeader {
  padding: 26px clamp(20px, 5vw, 40px);
  border-bottom: 1px solid var(--color-border);
}

.letterHeader h1 {
  margin-bottom: 8px;
  font-size: clamp(28px, 5vw, 42px);
}

.letterHeader p:last-child {
  margin: 0;
  color: var(--color-text-secondary);
}

iframe {
  display: block;
  width: 100%;
  min-height: 70vh;
  border: 0;
  background: var(--color-bg-secondary);
}

.letterContent {
  padding: 28px clamp(20px, 5vw, 40px);
  line-height: 1.8;
  color: var(--color-text-primary);
}

.letterTextBlock {
  margin: 0 0 14px;
  white-space: pre-wrap;
}

.letterImageBlock {
  display: block;
  max-width: 100%;
  height: auto;
  border-radius: 8px;
  margin: 14px 0;
}

[hidden] { display: none !important; }

@media (max-width: 680px) {
  .shell {
    padding: 18px 12px;
    place-items: stretch;
  }

  .countdown-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}