/* ================================
   URANIUM PLAYGROUND · core styles
   ================================ */

:root {
  --bg: #07090e;
  --bg-2: #0d111a;
  --panel: rgba(18, 22, 33, 0.75);
  --panel-2: rgba(28, 33, 48, 0.55);
  --border: rgba(120, 140, 180, 0.15);
  --border-strong: rgba(120, 140, 180, 0.3);

  --text: #e8ecf5;
  --text-dim: #8a93a6;
  --text-faint: #5d6578;

  --accent: #7cf9c5;       /* mint/radioactive */
  --accent-2: #9d7bff;     /* violet */
  --proton: #ff5a6a;       /* red */
  --proton-glow: rgba(255, 90, 106, 0.5);
  --neutron: #4ea9ff;      /* blue */
  --neutron-glow: rgba(78, 169, 255, 0.5);
  --danger: #ff4e7c;
  --warn: #ffcf4a;

  --radius: 14px;
  --radius-lg: 20px;
  --shadow: 0 20px 50px -20px rgba(0, 0, 0, 0.6);
  --shadow-glow: 0 0 40px rgba(124, 249, 197, 0.15);

  --mono: 'JetBrains Mono', ui-monospace, 'SF Mono', Menlo, monospace;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html, body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  font-size: 16px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  scrollbar-width: none;
  -ms-overflow-style: none;
}
html::-webkit-scrollbar,
body::-webkit-scrollbar {
  display: none;
}

/* ====== BACKGROUND ====== */
.bg-grid {
  position: fixed; inset: 0;
  background-image:
    linear-gradient(rgba(120,140,180,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(120,140,180,0.04) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: radial-gradient(ellipse at center, #000 0%, transparent 70%);
  pointer-events: none;
  z-index: 0;
}
.bg-glow {
  position: fixed;
  top: -200px; left: 50%;
  width: 900px; height: 900px;
  transform: translateX(-50%);
  background: radial-gradient(circle, rgba(124,249,197,0.08), transparent 60%);
  pointer-events: none;
  z-index: 0;
}

/* ====== HERO ====== */
.hero {
  position: relative;
  z-index: 1;
  max-width: 1200px;
  margin: 0 auto;
  padding: 80px 24px 60px;
  text-align: center;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  border: 1px solid var(--border-strong);
  border-radius: 100px;
  font-size: 11px;
  letter-spacing: 0.15em;
  color: var(--text-dim);
  background: var(--panel);
  backdrop-filter: blur(10px);
  margin-bottom: 24px;
}
.badge .dot {
  width: 8px; height: 8px; border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 10px var(--accent);
  animation: pulse 2s infinite;
}
@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.85); }
}

.hero h1 {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.05;
  margin-bottom: 20px;
}
.accent {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.subtitle {
  font-size: clamp(1rem, 2vw, 1.2rem);
  color: var(--text-dim);
  max-width: 640px;
  margin: 0 auto 36px;
}

.nav-pills {
  display: flex;
  justify-content: center;
  gap: 10px;
  flex-wrap: wrap;
}
.pill {
  padding: 10px 18px;
  border: 1px solid var(--border-strong);
  border-radius: 100px;
  color: var(--text);
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
  background: var(--panel);
  backdrop-filter: blur(10px);
  transition: all 0.2s;
}
.pill:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-1px);
}

/* ====== SECTIONS ====== */
.section {
  position: relative;
  z-index: 1;
  max-width: 1200px;
  margin: 0 auto;
  padding: 80px 24px;
}

.section-head {
  margin-bottom: 40px;
  text-align: center;
}
.step {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--accent);
  letter-spacing: 0.2em;
  padding: 4px 10px;
  border: 1px solid var(--border-strong);
  border-radius: 6px;
  display: inline-block;
  margin-bottom: 16px;
}
.section-head h2 {
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 10px;
}
.section-head p {
  color: var(--text-dim);
  font-size: 1rem;
}

/* ====== CARDS (info rapid) ====== */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
}

.iso-card {
  position: relative;
  padding: 24px;
  background: var(--panel);
  backdrop-filter: blur(14px);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: transform 0.3s, border-color 0.3s;
}
.iso-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: var(--iso-color, var(--accent));
  opacity: 0.8;
}
.iso-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-strong);
}
.iso-card-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 6px;
}
.iso-card-head h3 {
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}
.iso-card-head .z {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-faint);
}
.iso-card-tag {
  display: inline-block;
  padding: 3px 8px;
  border-radius: 6px;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.05em;
  margin-bottom: 16px;
  background: rgba(255,255,255,0.05);
  color: var(--iso-color, var(--accent));
  border: 1px solid currentColor;
}

.iso-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin: 14px 0;
  padding: 14px;
  background: rgba(0,0,0,0.25);
  border-radius: 10px;
}
.iso-stats > div {
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.iso-stats span:first-child {
  font-size: 10px;
  color: var(--text-faint);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}
.iso-stats span:last-child {
  font-family: var(--mono);
  font-size: 14px;
  color: var(--text);
  font-weight: 600;
}

.iso-card p {
  color: var(--text-dim);
  font-size: 14px;
  line-height: 1.5;
}

/* ====== SIMULATOR ====== */
.simulator-grid {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 30px;
  align-items: start;
}
@media (max-width: 900px) {
  .simulator-grid { grid-template-columns: 1fr; }
}

.canvas-wrap {
  position: relative;
  background: radial-gradient(circle at center, #0f1320 0%, #070910 100%);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  aspect-ratio: 1/1;
  box-shadow: var(--shadow-glow);
}
.canvas-wrap.small {
  aspect-ratio: auto;
  height: 340px;
}
.canvas-wrap canvas {
  width: 100%;
  height: 100%;
  display: block;
}

.canvas-overlay {
  position: absolute;
  inset: 0;
  padding: 16px;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  pointer-events: none;
}
.iso-tag {
  font-family: var(--mono);
  font-size: 14px;
  font-weight: 600;
  padding: 6px 12px;
  background: rgba(0,0,0,0.5);
  border: 1px solid var(--border-strong);
  border-radius: 8px;
  color: var(--accent);
  backdrop-filter: blur(10px);
}
.legend {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 12px;
  color: var(--text-dim);
}
.legend span {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  background: rgba(0,0,0,0.5);
  border-radius: 6px;
  backdrop-filter: blur(10px);
}
.legend i {
  width: 10px; height: 10px;
  border-radius: 50%;
  display: inline-block;
}
.legend .proton { background: var(--proton); box-shadow: 0 0 8px var(--proton-glow); }
.legend .neutron { background: var(--neutron); box-shadow: 0 0 8px var(--neutron-glow); }

/* controls */
.controls {
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.control-block label {
  display: block;
  font-size: 12px;
  color: var(--text-dim);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 10px;
}

.iso-selector {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
}
.iso-selector.compact { grid-template-columns: repeat(4, 1fr); }
.iso-selector button {
  padding: 12px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  color: var(--text);
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
}
.iso-selector button:hover {
  border-color: var(--border-strong);
  transform: translateY(-1px);
}
.iso-selector button.active {
  background: rgba(124, 249, 197, 0.1);
  border-color: var(--accent);
  color: var(--accent);
  box-shadow: 0 0 20px rgba(124, 249, 197, 0.2);
}

.stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
}
.stat {
  padding: 14px 16px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.stat-label {
  font-size: 11px;
  color: var(--text-faint);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}
.stat-value {
  font-family: var(--mono);
  font-size: 22px;
  font-weight: 700;
  color: var(--text);
}

.stability {
  padding: 16px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
}
.stability-head {
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  margin-bottom: 10px;
}
.stability-head span:last-child {
  color: var(--accent);
  font-weight: 600;
}
.stability-bar {
  height: 8px;
  background: rgba(255,255,255,0.05);
  border-radius: 100px;
  overflow: hidden;
  margin-bottom: 8px;
}
.stability-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--danger), var(--warn), var(--accent));
  border-radius: 100px;
  transition: width 0.5s ease;
}
.stability small {
  color: var(--text-faint);
  font-family: var(--mono);
  font-size: 11px;
}

.actions {
  display: flex;
  gap: 10px;
}

.btn {
  padding: 14px 20px;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.2s;
  font-family: inherit;
}
.btn-primary {
  background: linear-gradient(135deg, var(--accent), #5ee1a5);
  color: #06120d;
  flex: 1;
}
.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 10px 30px rgba(124, 249, 197, 0.3);
}
.btn-ghost {
  background: var(--panel);
  border-color: var(--border-strong);
  color: var(--text);
}
.btn-ghost:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.btn-danger {
  background: linear-gradient(135deg, var(--danger), #ff7a4e);
  color: white;
  width: 100%;
  margin-top: 16px;
  padding: 16px;
  font-size: 15px;
}
.btn-danger:hover {
  transform: translateY(-1px);
  box-shadow: 0 10px 30px rgba(255, 78, 124, 0.3);
}

.note {
  font-size: 13px;
  color: var(--text-dim);
  padding: 14px;
  background: rgba(124, 249, 197, 0.05);
  border-left: 3px solid var(--accent);
  border-radius: 8px;
  line-height: 1.6;
}
.note b { color: var(--text); }

/* ====== LAB SECTION ====== */
.lab-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}
.lab-card.wide { grid-column: 1 / -1; }
@media (max-width: 900px) {
  .lab-grid { grid-template-columns: 1fr; }
  .lab-card.wide { grid-column: auto; }
}

.lab-card {
  padding: 24px;
  background: var(--panel);
  backdrop-filter: blur(14px);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
}
.lab-head { margin-bottom: 20px; }
.lab-head h3 {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 6px;
}
.lab-head p {
  font-size: 13px;
  color: var(--text-dim);
}

.fission-formula {
  margin-top: 16px;
  padding: 18px;
  background: rgba(0,0,0,0.3);
  border-radius: 10px;
  text-align: center;
}
.formula {
  font-family: var(--mono);
  font-size: 17px;
  color: var(--text);
  margin-bottom: 14px;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 4px;
  line-height: 1.4;
}
.formula.big {
  font-size: 22px;
  color: var(--warn);
  font-weight: 700;
  letter-spacing: 0.05em;
  font-family: 'Inter', sans-serif;
  margin-top: 8px;
  margin-bottom: 0;
}
.formula .energy {
  color: var(--warn);
  text-shadow: 0 0 10px rgba(255, 207, 74, 0.5);
}
.fission-formula small {
  display: block;
  margin-top: 8px;
  color: var(--text-faint);
  font-size: 12px;
}

/* ====== NUCLEAR NOTATION (A top, Z bottom, on the left of element) ====== */
.nuclide {
  display: inline-flex;
  align-items: center;
  gap: 2px;
  font-family: var(--mono);
  font-weight: 600;
  color: var(--text);
  white-space: nowrap;
}
.nuclide .nums {
  display: inline-flex;
  flex-direction: column;
  align-items: flex-end;
  justify-content: center;
  line-height: 1;
  font-size: 0.62em;
  color: var(--text-dim);
}
.nuclide .nums sup,
.nuclide .nums sub {
  display: block;
  line-height: 1.05;
  vertical-align: baseline;
  font-size: inherit;
  top: 0;
  position: static;
}
.nuclide .nums sup { color: var(--accent); }
.nuclide .nums sub { color: var(--accent-2); }

/* conservation proof lines */
.conservation {
  display: flex;
  flex-direction: column;
  gap: 4px;
  margin: 10px 0 14px;
  padding: 10px 12px;
  background: rgba(124, 249, 197, 0.05);
  border: 1px dashed rgba(124, 249, 197, 0.25);
  border-radius: 8px;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-dim);
}
.conservation .cons-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
}
.conservation b {
  color: var(--accent);
  margin-right: 4px;
}
.conservation .check {
  color: var(--accent);
  font-weight: 700;
  padding: 2px 8px;
  background: rgba(124, 249, 197, 0.1);
  border-radius: 100px;
  font-size: 11px;
}

/* nuclides inside note paragraph */
.note .nuclide { font-size: 14px; margin: 0 1px; }

/* compare table */
.compare {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}
.compare th, .compare td {
  padding: 12px 14px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}
.compare th {
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 700;
}
.compare .col-235 { color: var(--accent); }
.compare .col-238 { color: var(--accent-2); }
.compare td:first-child { color: var(--text-dim); font-size: 13px; }
.compare .yes { color: var(--accent); font-weight: 700; }
.compare .no { color: var(--danger); font-weight: 700; }

/* time grid */
.time-grid {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 20px;
  align-items: stretch;
}
@media (max-width: 780px) {
  .time-grid { grid-template-columns: 1fr; }
}

.atoms-wrap {
  position: relative;
  background: radial-gradient(circle at center, #0f1320 0%, #070910 100%);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  min-height: 260px;
}
.atoms-wrap canvas {
  width: 100%;
  height: 100%;
  display: block;
}
.atoms-overlay {
  position: absolute;
  top: 12px; left: 12px; right: 12px;
  display: flex;
  justify-content: space-between;
  gap: 10px;
  pointer-events: none;
}
.atoms-overlay > div {
  background: rgba(0,0,0,0.6);
  backdrop-filter: blur(10px);
  padding: 8px 12px;
  border-radius: 8px;
  border: 1px solid var(--border-strong);
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.atoms-label {
  font-size: 10px;
  color: var(--text-faint);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}
.atoms-value {
  font-family: var(--mono);
  font-size: 18px;
  font-weight: 700;
  color: var(--accent);
}

.time-controls {
  display: flex;
  flex-direction: column;
  gap: 18px;
  padding: 20px;
  background: rgba(0,0,0,0.2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}
.time-actions {
  display: flex;
  gap: 10px;
}
.time-actions .btn { flex: 1; padding: 12px; }

.half-life-info {
  padding: 12px;
  background: rgba(124, 249, 197, 0.05);
  border: 1px solid rgba(124, 249, 197, 0.2);
  border-radius: 8px;
  font-size: 13px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.half-life-info span { color: var(--text-dim); }
.half-life-info b { color: var(--accent); font-family: var(--mono); }

/* slider */
input[type="range"] {
  width: 100%;
  -webkit-appearance: none;
  appearance: none;
  height: 6px;
  background: rgba(255,255,255,0.08);
  border-radius: 100px;
  outline: none;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
  box-shadow: 0 0 10px var(--accent);
  border: 2px solid #06120d;
}
input[type="range"]::-moz-range-thumb {
  width: 18px; height: 18px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
  border: 2px solid #06120d;
}
.speed-labels {
  display: flex;
  justify-content: space-between;
  font-size: 10px;
  color: var(--text-faint);
  margin-top: 6px;
  font-family: var(--mono);
  letter-spacing: 0.1em;
}

/* ====== FOOTER ====== */
footer {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 40px 20px 60px;
  color: var(--text-faint);
  font-size: 13px;
}

/* ====== UTILITY ====== */
.shake {
  animation: shake 0.5s;
}
@keyframes shake {
  0%, 100% { transform: translate(0, 0); }
  20% { transform: translate(-4px, 2px); }
  40% { transform: translate(4px, -2px); }
  60% { transform: translate(-3px, -3px); }
  80% { transform: translate(3px, 3px); }
}

.flash {
  animation: flash 0.6s;
}
@keyframes flash {
  0%, 100% { background-color: transparent; }
  30% { background-color: rgba(255, 207, 74, 0.2); }
}

@keyframes statFlash {
  0% { color: var(--accent); transform: scale(1.2); }
  100% { color: var(--text); transform: scale(1); }
}
.stat-flash {
  animation: statFlash 0.8s ease-out;
}

.btn:disabled {
  cursor: not-allowed;
  transform: none !important;
  box-shadow: none !important;
}
.btn-done {
  background: rgba(124, 249, 197, 0.12) !important;
  border: 1px solid var(--accent) !important;
  color: var(--accent) !important;
}
.btn-done:hover {
  transform: none;
  box-shadow: none;
}

/* ====== TEORIE (link către resurse PULS) ====== */
.theory-embed .theory-list {
  max-width: 720px;
  margin: 0 auto 1rem;
  padding-left: 1.25rem;
  color: var(--text-dim);
  line-height: 1.65;
}
.theory-embed .theory-list li { margin-bottom: 0.65rem; }
.theory-mono {
  font-family: var(--mono);
  font-size: 0.95em;
  color: var(--text);
}
.theory-more {
  text-align: center;
  margin-top: 1.25rem;
  font-size: 14px;
}
.theory-more a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid rgba(124, 249, 197, 0.35);
}
.theory-more a:hover { color: var(--text); border-bottom-color: var(--accent); }