/* === Design systém – dark téma === */
:root {
  /* Barvy */
  --color-bg: #09090b;
  --color-surface: rgba(255, 255, 255, 0.04);
  --color-surface-hover: rgba(255, 255, 255, 0.06);
  --color-text: #fafafa;
  --color-text-muted: #71717a;
  --color-border: rgba(255, 255, 255, 0.08);
  --color-accent: #ef4444;
  --color-accent-soft: rgba(239, 68, 68, 0.12);
  --color-accent-hover: #dc2626;
  --color-accent-glow: rgba(239, 68, 68, 0.25);
  --color-link: #a1a1aa;

  /* Typografie */
  --font: 'DM Sans', system-ui, -apple-system, sans-serif;

  /* Rozměry */
  --radius-sm: 10px;
  --radius-md: 14px;
  --radius-lg: 22px;
  --radius-xl: 30px;

  /* Stíny */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 16px 48px rgba(0, 0, 0, 0.5);

  /* Animace */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --duration-fast: 200ms;
  --duration-normal: 500ms;
}

/* === Reset === */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
}

body {
  font-family: var(--font);
  color: var(--color-text);
  background: var(--color-bg);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  -webkit-font-smoothing: antialiased;
  /* Jemný radiální gradient pro hloubku */
  background-image:
    radial-gradient(ellipse 60% 50% at 50% 0%, rgba(239, 68, 68, 0.06) 0%, transparent 70%),
    radial-gradient(ellipse 80% 40% at 50% 100%, rgba(120, 60, 200, 0.04) 0%, transparent 70%);
  background-attachment: fixed;
}

/* === Layout === */
.app {
  max-width: 520px;
  width: 100%;
  padding: 64px 24px 48px;
}

/* === Hlavička === */
.hero {
  text-align: center;
  margin-bottom: 44px;
}

.hero h1 {
  font-size: clamp(1.6rem, 5vw, 2.2rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.25;
  color: var(--color-text);
}

.hero h1 em {
  font-style: normal;
  color: var(--color-accent);
}

/* === Přepínač režimů === */
.mode-switch {
  display: flex;
  gap: 2px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 4px;
  margin-bottom: 28px;
}

.mode-btn {
  flex: 1;
  padding: 10px 16px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-text-muted);
  font-family: var(--font);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--duration-fast) var(--ease-out);
}

.mode-btn.active {
  background: rgba(255, 255, 255, 0.1);
  color: var(--color-text);
}

.mode-btn:hover:not(.active) {
  color: var(--color-text);
  background: rgba(255, 255, 255, 0.03);
}

/* === Panely === */
.panel {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  margin-bottom: 20px;
  backdrop-filter: blur(12px);
  animation: fadeIn var(--duration-normal) var(--ease-out);
}

.hidden {
  display: none !important;
}

/* === Formulářové prvky === */
label {
  display: block;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--color-text-muted);
  margin-bottom: 8px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

input[type="date"] {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-family: var(--font);
  font-size: 1rem;
  color: var(--color-text);
  background: rgba(255, 255, 255, 0.03);
  transition: border-color var(--duration-fast), box-shadow var(--duration-fast);
  margin-bottom: 16px;
  color-scheme: dark;
}

input[type="date"]:focus {
  outline: none;
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-soft);
}

input[type="date"]:hover {
  border-color: rgba(255, 255, 255, 0.15);
}

.date-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.date-row input[type="date"] {
  margin-bottom: 16px;
}

/* === Tlačítko === */
.btn-primary {
  width: 100%;
  padding: 14px 24px;
  border: none;
  border-radius: var(--radius-sm);
  background: var(--color-accent);
  color: #fff;
  font-family: var(--font);
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  cursor: pointer;
  transition: all var(--duration-fast) var(--ease-out);
}

.btn-primary:hover {
  background: var(--color-accent-hover);
  box-shadow: 0 0 24px var(--color-accent-glow);
  transform: translateY(-1px);
}

.btn-primary:active {
  transform: translateY(0);
  box-shadow: none;
}

/* === Chybová hláška === */
.error-box {
  background: var(--color-accent-soft);
  color: #fca5a5;
  border: 1px solid rgba(239, 68, 68, 0.2);
  border-radius: var(--radius-sm);
  padding: 12px 16px;
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: 20px;
  animation: fadeIn var(--duration-fast) var(--ease-out);
}

/* === Výsledková karta === */
.result-card {
  text-align: center;
  padding: 48px 24px 36px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  margin-bottom: 20px;
  backdrop-filter: blur(12px);
  animation: slideUp var(--duration-normal) var(--ease-out);
  position: relative;
  overflow: hidden;
}

/* Jemná červená záře za číslem */
.result-card::before {
  content: '';
  position: absolute;
  top: 20%;
  left: 50%;
  transform: translateX(-50%);
  width: 200px;
  height: 200px;
  background: radial-gradient(circle, var(--color-accent-glow) 0%, transparent 70%);
  pointer-events: none;
  opacity: 0.5;
}

.result-number {
  font-size: clamp(4rem, 12vw, 8rem);
  font-weight: 900;
  color: var(--color-accent);
  line-height: 1;
  letter-spacing: -0.04em;
  margin-bottom: 8px;
  position: relative;
  /* Jemný text-shadow pro glow efekt */
  text-shadow: 0 0 40px var(--color-accent-glow);
}

.result-label {
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--color-text-muted);
  margin-bottom: 4px;
  position: relative;
}

.result-detail {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  opacity: 0.7;
  margin-bottom: 0;
  position: relative;
}

/* === Rozbalovací seznam dat === */
.date-list-wrapper {
  margin-top: 32px;
  text-align: left;
  border-top: 1px solid var(--color-border);
  padding-top: 20px;
  position: relative;
}

.date-list-wrapper summary {
  cursor: pointer;
  font-weight: 500;
  color: var(--color-link);
  font-size: 0.9rem;
  padding: 4px 0;
  transition: color var(--duration-fast);
}

.date-list-wrapper summary:hover {
  color: var(--color-text);
}

.date-list {
  columns: 2;
  gap: 16px;
  list-style: none;
  padding: 0;
  margin: 16px 0 0;
}

.date-list li {
  padding: 7px 0;
  color: var(--color-text-muted);
  font-size: 0.85rem;
  font-variant-numeric: tabular-nums;
  border-bottom: 1px solid var(--color-border);
  break-inside: avoid;
}

/* === Patička === */
.footer {
  text-align: center;
  padding-top: 24px;
  margin-top: 8px;
  border-top: 1px solid var(--color-border);
}

.footer-promo {
  color: var(--color-text-muted);
  font-size: 0.85rem;
  line-height: 1.7;
  margin-bottom: 16px;
}

.footer-promo a {
  color: var(--color-accent);
  text-decoration: none;
  font-weight: 600;
  transition: opacity var(--duration-fast);
}

.footer-promo a:hover {
  text-decoration: underline;
  opacity: 0.85;
}

.footer-copy {
  color: var(--color-text-muted);
  font-size: 0.75rem;
  opacity: 0.4;
}

/* === Animace === */
@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(28px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* === Responzivní úpravy === */
@media (max-width: 480px) {
  .app {
    padding: 40px 16px 32px;
  }

  .panel {
    padding: 24px 20px;
  }

  .date-row {
    grid-template-columns: 1fr;
    gap: 0;
  }

  .date-list {
    columns: 1;
  }

  .result-card {
    padding: 40px 20px 28px;
  }
}