/* =========================================================================
   Chess Frame — Design System
   Dark glassmorphism · gold/amber accent · floating pieces.
   Same art direction as before, rebuilt for a richer, more dynamic UX.
   ========================================================================= */

:root {
  /* Core palette */
  --primary-dark: #1a1a2e;
  --primary-darker: #0f0f1e;
  --primary-darkest: #080814;
  --surface-1: #16162a;

  --accent: #f39c12;
  --accent-2: #e74c3c;
  --accent-soft: rgba(243, 156, 18, 0.16);
  --accent-glow: rgba(243, 156, 18, 0.45);
  --info: #4aa3df;

  --glass-bg: rgba(255, 255, 255, 0.045);
  --glass-bg-2: rgba(255, 255, 255, 0.07);
  --glass-border: rgba(255, 255, 255, 0.1);
  --glass-border-strong: rgba(255, 255, 255, 0.18);

  --text-primary: #f5f5fb;
  --text-secondary: #b8b8c8;
  --text-muted: #7e7e92;

  --success: #27ae60;
  --danger: #e74c3c;
  --warning: #f1c40f;

  /* Board */
  --board-light: #ead9b0;
  --board-dark: #b07d52;
  --board-frame: rgba(0, 0, 0, 0.35);

  --card-shadow: 0 12px 40px rgba(0, 0, 0, 0.38);
  --radius-lg: 22px;
  --radius-md: 14px;
  --radius-sm: 10px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);

  --font-display: "Sora", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-ui: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", ui-monospace, "Courier New", monospace;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  /* Solid dark base so no white ever shows through, at any scroll height. */
  background-color: var(--primary-darkest);
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-ui);
  background: radial-gradient(1200px 800px at 15% -10%, #232347 0%, transparent 55%),
              radial-gradient(1000px 700px at 110% 10%, #2a1d33 0%, transparent 50%),
              linear-gradient(135deg, var(--primary-dark) 0%, var(--primary-darker) 60%, var(--primary-darkest) 100%);
  min-height: 100vh;
  color: var(--text-primary);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* Animated ambient glow */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -2;
  background-image:
    radial-gradient(circle at 20% 50%, rgba(243, 156, 18, 0.10) 0%, transparent 45%),
    radial-gradient(circle at 80% 80%, rgba(231, 76, 60, 0.06) 0%, transparent 45%),
    radial-gradient(circle at 45% 20%, rgba(74, 163, 223, 0.05) 0%, transparent 45%);
  animation: ambientPulse 22s ease-in-out infinite;
}

/* Subtle chessboard texture */
body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -3;
  background-image:
    linear-gradient(45deg, rgba(255, 255, 255, 0.012) 25%, transparent 25%, transparent 75%, rgba(255, 255, 255, 0.012) 75%),
    linear-gradient(45deg, rgba(255, 255, 255, 0.012) 25%, transparent 25%, transparent 75%, rgba(255, 255, 255, 0.012) 75%);
  background-size: 120px 120px;
  background-position: 0 0, 60px 60px;
  opacity: 0.6;
  pointer-events: none;
}

@keyframes ambientPulse {
  0%, 100% { opacity: 0.55; transform: scale(1); }
  50% { opacity: 0.9; transform: scale(1.04); }
}

/* ============================ Layout ============================ */
.main-container {
  padding: 2rem;
  max-width: 1240px;
  margin: 0 auto;
  animation: fadeInUp 0.8s ease-out;
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(28px); }
  to { opacity: 1; transform: translateY(0); }
}

.section-stack > * + * { margin-top: 1.75rem; }

/* Two-column studio: form + sticky board */
.studio-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
  gap: 1.75rem;
  align-items: start;
}

.studio-form { min-width: 0; }
.studio-form > * + * { margin-top: 1.75rem; }

.studio-board-col {
  position: sticky;
  top: 1.5rem;
  min-width: 0;
}

/* ============================ Header ============================ */
.header-section {
  text-align: center;
  margin-bottom: 2.5rem;
  position: relative;
  padding: 1rem 0 0.5rem;
}

.floating-pieces {
  position: absolute;
  inset: -2rem 0 0 0;
  height: 130%;
  pointer-events: none;
  overflow: visible;
  z-index: 0;
}

.chess-piece {
  position: absolute;
  font-size: 2.4rem;
  color: rgba(243, 156, 18, 0.16);
  text-shadow: 0 6px 24px rgba(243, 156, 18, 0.18);
  animation: floatPiece 8s ease-in-out infinite;
  will-change: transform;
  user-select: none;
}

.chess-piece:nth-child(1) { top: 4%;  left: 6%;  font-size: 3rem;   animation-delay: 0s;   color: rgba(243, 156, 18, 0.14); }
.chess-piece:nth-child(2) { top: 12%; right: 9%; font-size: 2.2rem; animation-delay: 1.4s; color: rgba(231, 76, 60, 0.12); }
.chess-piece:nth-child(3) { bottom: 6%; left: 16%; font-size: 1.9rem; animation-delay: 2.6s; color: rgba(255, 255, 255, 0.07); }
.chess-piece:nth-child(4) { bottom: 12%; right: 14%; font-size: 2.7rem; animation-delay: 3.8s; color: rgba(243, 156, 18, 0.12); }
.chess-piece:nth-child(5) { top: 40%; left: 2%;  font-size: 1.7rem; animation-delay: 1s;   color: rgba(74, 163, 223, 0.10); }
.chess-piece:nth-child(6) { top: 46%; right: 3%; font-size: 2rem;   animation-delay: 2s;   color: rgba(243, 156, 18, 0.10); }

@keyframes floatPiece {
  0%, 100% { transform: translateY(0) rotate(0deg); }
  50% { transform: translateY(-18px) rotate(8deg); }
}

.logo-container {
  position: relative;
  display: inline-block;
  margin-bottom: 1rem;
  z-index: 1;
}

.logo-container::after {
  content: "";
  position: absolute;
  inset: 8%;
  border-radius: 50%;
  background: radial-gradient(circle, var(--accent-glow) 0%, transparent 70%);
  filter: blur(18px);
  opacity: 0.5;
  z-index: -1;
  animation: logoGlow 4s ease-in-out infinite;
}

.logo-container img {
  width: 116px;
  height: 116px;
  filter: drop-shadow(0 8px 26px rgba(243, 156, 18, 0.35));
  transition: var(--transition);
  animation: logoFloat 6s ease-in-out infinite;
}

.logo-container:hover img {
  transform: scale(1.06) rotate(4deg);
  filter: drop-shadow(0 10px 36px rgba(243, 156, 18, 0.6));
}

@keyframes logoFloat { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-8px); } }
@keyframes logoGlow { 0%, 100% { opacity: 0.35; } 50% { opacity: 0.7; } }

.chess-brand {
  font-family: var(--font-display);
  font-size: clamp(2.6rem, 6vw, 4rem);
  font-weight: 800;
  line-height: 1.05;
  background: linear-gradient(110deg, #ffd479, var(--accent) 35%, var(--accent-2) 75%, #ff8a5c);
  background-size: 220% auto;
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin: 0 0 0.4rem;
  letter-spacing: -1.5px;
  animation: brandShimmer 6s ease-in-out infinite;
}

@keyframes brandShimmer {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

.subtitle {
  font-size: clamp(1rem, 2.4vw, 1.25rem);
  color: var(--text-secondary);
  font-weight: 300;
  letter-spacing: 0.4px;
  max-width: 620px;
  margin: 0 auto;
}

/* ============================ Glass card ============================ */
.glass-card {
  position: relative;
  background: var(--glass-bg);
  backdrop-filter: blur(22px);
  -webkit-backdrop-filter: blur(22px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: 1.85rem;
  box-shadow: var(--card-shadow);
  transition: var(--transition);
  overflow: hidden;
}

.glass-card::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), var(--accent-2), transparent);
  opacity: 0.55;
}

.glass-card.interactive:hover {
  transform: translateY(-3px);
  border-color: var(--glass-border-strong);
  box-shadow: 0 18px 52px rgba(0, 0, 0, 0.45);
}

/* Section header with step badge */
.section-head {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  margin-bottom: 1.35rem;
}

.step-badge {
  flex: 0 0 auto;
  width: 38px;
  height: 38px;
  display: grid;
  place-items: center;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #1a1a2e;
  font-weight: 800;
  font-size: 1.05rem;
  box-shadow: 0 4px 16px rgba(243, 156, 18, 0.3);
}

.section-head h2 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 700;
  margin: 0;
  color: var(--text-primary);
}

.section-head .section-sub {
  display: block;
  font-family: var(--font-ui);
  font-size: 0.82rem;
  font-weight: 400;
  color: var(--text-muted);
  margin-top: 2px;
}

/* ============================ Explainer / pills ============================ */
.pill-row {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  margin-bottom: 1.1rem;
}

.pill {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1.4rem;
  background: transparent;
  border: 1.5px solid var(--glass-border);
  border-radius: 50px;
  color: var(--text-secondary);
  font-family: var(--font-ui);
  font-weight: 500;
  font-size: 0.92rem;
  cursor: pointer;
  transition: var(--transition);
}

.pill:hover { color: var(--text-primary); border-color: var(--accent); transform: translateY(-1px); }
.pill.active {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #1a1a2e;
  border-color: transparent;
  font-weight: 600;
}

.info-panel {
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 1.25rem 1.35rem;
  background: rgba(255, 255, 255, 0.025);
  animation: slideDown 0.3s ease-out;
}
.info-panel h4 { color: var(--accent); margin: 0 0 0.6rem; font-family: var(--font-display); }
.info-panel p { color: var(--text-secondary); line-height: 1.65; margin: 0 0 0.6rem; }
.info-panel code { color: var(--accent); background: rgba(243, 156, 18, 0.1); padding: 0.05rem 0.4rem; border-radius: 5px; }
.code-sample {
  background: rgba(0, 0, 0, 0.28);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-sm);
  padding: 0.9rem 1rem;
  margin-top: 0.75rem;
}
.code-sample pre {
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  margin: 0;
  white-space: pre-wrap;
  word-break: break-word;
}
.code-sample .label { font-size: 0.85rem; color: var(--text-secondary); margin: 0 0 0.5rem; }

/* ============================ Tabs ============================ */
.tab-row {
  display: inline-flex;
  gap: 0.35rem;
  padding: 0.35rem;
  background: rgba(0, 0, 0, 0.22);
  border: 1px solid var(--glass-border);
  border-radius: 50px;
  margin-bottom: 1.25rem;
}

.tab-button {
  padding: 0.55rem 1.5rem;
  background: transparent;
  border: none;
  border-radius: 50px;
  color: var(--text-secondary);
  font-family: var(--font-ui);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}
.tab-button:hover { color: var(--text-primary); }
.tab-button.active {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #1a1a2e;
  box-shadow: 0 4px 16px rgba(243, 156, 18, 0.28);
}

.tab-content { animation: fadeIn 0.35s ease-out; }

/* ============================ Form ============================ */
.form-group { margin-bottom: 1.4rem; }
.form-grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 1.4rem; }

.form-label {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  margin-bottom: 0.5rem;
  color: var(--text-secondary);
  font-weight: 600;
  text-transform: uppercase;
  font-size: 0.76rem;
  letter-spacing: 1.2px;
}

.form-control {
  width: 100%;
  padding: 0.9rem 1rem;
  background: rgba(255, 255, 255, 0.045);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-family: var(--font-ui);
  font-size: 1rem;
  transition: var(--transition);
}
.form-control:hover { border-color: var(--glass-border-strong); }
.form-control:focus {
  outline: none;
  border-color: var(--accent);
  background: rgba(255, 255, 255, 0.07);
  box-shadow: 0 0 0 3px rgba(243, 156, 18, 0.18);
}
.form-control::placeholder { color: rgba(184, 184, 200, 0.45); }

textarea.form-control { resize: vertical; min-height: 110px; font-family: var(--font-mono); font-size: 0.92rem; line-height: 1.6; }

.field-hint { color: var(--text-muted); display: block; margin-top: 0.5rem; font-size: 0.83rem; line-height: 1.5; }

.optional-divider {
  display: flex;
  align-items: center;
  gap: 1rem;
  color: var(--text-muted);
  font-size: 0.85rem;
  margin: 1.5rem 0;
}
.optional-divider::before, .optional-divider::after {
  content: ""; flex: 1; height: 1px;
  background: linear-gradient(90deg, transparent, var(--glass-border), transparent);
}

/* Live validation status */
.input-status {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 0.6rem;
  font-size: 0.86rem;
  min-height: 1.2rem;
  transition: var(--transition);
}
.input-status .dot { width: 8px; height: 8px; border-radius: 50%; flex: 0 0 auto; }
.input-status.is-ok { color: #6ee7a8; }
.input-status.is-ok .dot { background: var(--success); box-shadow: 0 0 8px var(--success); }
.input-status.is-error { color: #ff8a7a; }
.input-status.is-error .dot { background: var(--danger); box-shadow: 0 0 8px var(--danger); }
.input-status.is-idle { color: var(--text-muted); }
.input-status.is-idle .dot { background: var(--text-muted); }

/* Drop zone */
.drop-zone {
  border: 2px dashed var(--glass-border);
  border-radius: var(--radius-md);
  padding: 2.5rem 1.5rem;
  text-align: center;
  transition: var(--transition);
  cursor: pointer;
  background: rgba(255, 255, 255, 0.018);
}
.drop-zone:hover { border-color: var(--accent); background: rgba(243, 156, 18, 0.05); }
.drop-zone.dragover { border-color: var(--accent); background: rgba(243, 156, 18, 0.12); transform: scale(1.01); }
.drop-icon { font-size: 2.6rem; margin-bottom: 0.75rem; color: var(--accent); opacity: 0.8; }
.drop-zone p { margin: 0; color: var(--text-secondary); }

/* Tooltip */
.tip {
  position: relative;
  display: inline-grid;
  place-items: center;
  width: 16px; height: 16px;
  border-radius: 50%;
  border: 1px solid var(--glass-border-strong);
  color: var(--text-muted);
  font-size: 10px;
  font-weight: 700;
  cursor: help;
  flex: 0 0 auto;
}
.tip:hover, .tip:focus-visible { color: var(--accent); border-color: var(--accent); outline: none; }
.tip::after {
  content: attr(data-tip);
  position: absolute;
  bottom: calc(100% + 9px);
  left: 50%;
  transform: translateX(-50%) translateY(4px);
  width: max-content;
  max-width: 240px;
  padding: 0.6rem 0.8rem;
  background: #0c0c1a;
  border: 1px solid var(--glass-border-strong);
  border-radius: 8px;
  color: var(--text-secondary);
  font-size: 0.78rem;
  font-weight: 400;
  line-height: 1.45;
  text-transform: none;
  letter-spacing: normal;
  text-align: left;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease;
  z-index: 50;
}
.tip:hover::after, .tip:focus-visible::after { opacity: 1; transform: translateX(-50%) translateY(0); }

/* ============================ Presets ============================ */
.preset-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.9rem;
  margin-bottom: 1.4rem;
}
.preset-card {
  text-align: left;
  padding: 1.1rem;
  background: rgba(255, 255, 255, 0.03);
  border: 1.5px solid var(--glass-border);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: var(--transition);
  color: var(--text-secondary);
}
.preset-card:hover { transform: translateY(-3px); border-color: var(--glass-border-strong); }
.preset-card.active {
  border-color: var(--accent);
  background: rgba(243, 156, 18, 0.08);
  box-shadow: 0 0 0 3px rgba(243, 156, 18, 0.14), 0 10px 26px rgba(0, 0, 0, 0.3);
}
.preset-card .preset-icon { font-size: 1.5rem; margin-bottom: 0.4rem; }
.preset-card .preset-name { font-family: var(--font-display); font-weight: 700; color: var(--text-primary); font-size: 1rem; }
.preset-card .preset-desc { font-size: 0.8rem; line-height: 1.45; margin-top: 0.25rem; }

/* ============================ Advanced ============================ */
.advanced-toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.7rem 1.4rem;
  background: transparent;
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-family: var(--font-ui);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  transition: var(--transition);
}
.advanced-toggle:hover { border-color: var(--accent); color: var(--accent); }
.advanced-toggle-icon { transition: transform 0.3s; }
.advanced-toggle.expanded .advanced-toggle-icon { transform: rotate(180deg); }

.advanced-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem 1.75rem;
  padding: 1.5rem;
  margin-top: 1.1rem;
  background: rgba(0, 0, 0, 0.18);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  animation: slideDown 0.35s ease-out;
}

/* Range sliders */
.range-field .range-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.55rem;
}
.range-field .range-label { display: flex; align-items: center; gap: 0.4rem; color: var(--text-secondary); font-weight: 600; font-size: 0.82rem; text-transform: uppercase; letter-spacing: 0.8px; }
.range-value {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 600;
  color: #1a1a2e;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  padding: 0.15rem 0.6rem;
  border-radius: 7px;
  min-width: 46px;
  text-align: center;
}
.range-help { display: block; color: var(--text-muted); font-size: 0.78rem; line-height: 1.45; margin-top: 0.5rem; }

input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 5px;
  background: rgba(255, 255, 255, 0.12);
  outline: none;
  cursor: pointer;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 18px; height: 18px;
  border-radius: 50%;
  background: linear-gradient(135deg, #ffd479, var(--accent));
  border: 2px solid #1a1a2e;
  box-shadow: 0 0 0 3px rgba(243, 156, 18, 0.25), 0 2px 8px rgba(0, 0, 0, 0.4);
  transition: transform 0.15s ease;
}
input[type="range"]::-webkit-slider-thumb:hover { transform: scale(1.18); }
input[type="range"]::-moz-range-thumb {
  width: 18px; height: 18px;
  border-radius: 50%;
  background: linear-gradient(135deg, #ffd479, var(--accent));
  border: 2px solid #1a1a2e;
  box-shadow: 0 0 0 3px rgba(243, 156, 18, 0.25);
}

/* Switch (orientation) */
.switch-field { display: flex; align-items: flex-start; gap: 0.8rem; }
.switch {
  position: relative;
  flex: 0 0 auto;
  width: 46px; height: 26px;
  margin-top: 2px;
}
.switch input { opacity: 0; width: 0; height: 0; }
.switch .slider {
  position: absolute;
  inset: 0;
  border-radius: 50px;
  background: rgba(255, 255, 255, 0.14);
  border: 1px solid var(--glass-border);
  transition: var(--transition);
}
.switch .slider::before {
  content: "";
  position: absolute;
  height: 18px; width: 18px;
  left: 3px; top: 3px;
  border-radius: 50%;
  background: #f5f5fb;
  transition: var(--transition);
}
.switch input:checked + .slider { background: linear-gradient(135deg, var(--accent), var(--accent-2)); border-color: transparent; }
.switch input:checked + .slider::before { transform: translateX(20px); }
.switch input:focus-visible + .slider { box-shadow: 0 0 0 3px rgba(243, 156, 18, 0.3); }

/* ============================ Buttons ============================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.55rem;
  padding: 0.85rem 2rem;
  border: none;
  border-radius: 50px;
  font-family: var(--font-ui);
  font-weight: 700;
  letter-spacing: 0.4px;
  font-size: 0.92rem;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
  text-decoration: none;
}
.btn:disabled { opacity: 0.55; cursor: not-allowed; }
.btn::after {
  content: "";
  position: absolute;
  top: 50%; left: 50%;
  width: 0; height: 0;
  background: rgba(255, 255, 255, 0.22);
  border-radius: 50%;
  transform: translate(-50%, -50%);
  transition: width 0.6s, height 0.6s;
}
.btn:hover:not(:disabled)::after { width: 320%; height: 320%; }

.btn-sm { padding: 0.5rem 1.2rem; font-size: 0.82rem; }
.btn-lg { padding: 1.05rem 2rem; font-size: 1.05rem; width: 100%; }

.btn-primary { background: linear-gradient(135deg, var(--accent), var(--accent-2)); color: #fff; box-shadow: 0 6px 24px rgba(243, 156, 18, 0.32); }
.btn-primary:hover:not(:disabled) { transform: translateY(-2px); box-shadow: 0 10px 34px rgba(243, 156, 18, 0.45); }
.btn-success { background: linear-gradient(135deg, var(--success), #1f8f4f); color: #fff; box-shadow: 0 6px 24px rgba(39, 174, 96, 0.3); }
.btn-success:hover:not(:disabled) { transform: translateY(-2px); }
.btn-danger { background: linear-gradient(135deg, var(--danger), #c0392b); color: #fff; }
.btn-outline { background: transparent; border: 1.5px solid var(--accent); color: var(--accent); }
.btn-outline:hover:not(:disabled) { background: var(--accent); color: #1a1a2e; }
.btn-ghost { background: rgba(255, 255, 255, 0.05); border: 1px solid var(--glass-border); color: var(--text-secondary); }
.btn-ghost:hover:not(:disabled) { color: var(--text-primary); border-color: var(--glass-border-strong); }

.btn .spinner-dot {
  width: 7px; height: 7px; border-radius: 50%; background: currentColor;
  animation: btnPulse 1s ease-in-out infinite;
}

@keyframes btnPulse { 0%, 100% { opacity: 0.3; } 50% { opacity: 1; } }

/* ============================ Board panel ============================ */
.board-panel { padding: 1.5rem; }
.board-panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 1rem;
}
.board-panel-head h3 { font-family: var(--font-display); font-size: 1.05rem; margin: 0; color: var(--text-primary); }
.board-live-tag {
  display: inline-flex; align-items: center; gap: 0.4rem;
  font-size: 0.72rem; font-weight: 600; text-transform: uppercase; letter-spacing: 1px;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 0.25rem 0.65rem; border-radius: 50px;
}
.board-live-tag .dot { width: 7px; height: 7px; border-radius: 50%; background: var(--accent); animation: btnPulse 1.5s ease-in-out infinite; }

.board-frame {
  position: relative;
  width: 100%;
  aspect-ratio: 1 / 1;
  border-radius: 12px;
  padding: 22px;
  background: linear-gradient(135deg, #2b2b46, #1c1c30);
  box-shadow: inset 0 0 0 1px var(--glass-border), 0 14px 40px rgba(0, 0, 0, 0.45);
}

.board-grid {
  position: relative;
  width: 100%;
  height: 100%;
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  grid-template-rows: repeat(8, 1fr);
  border-radius: 6px;
  overflow: hidden;
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.4);
}

.cf-square { position: relative; }
.cf-square.light { background: var(--board-light); }
.cf-square.dark { background: var(--board-dark); }

.cf-square .coord {
  position: absolute;
  font-size: clamp(7px, 1.5vw, 11px);
  font-weight: 700;
  font-family: var(--font-ui);
  opacity: 0.6;
  pointer-events: none;
}
.cf-square .coord.file { right: 3px; bottom: 1px; }
.cf-square .coord.rank { left: 3px; top: 1px; }
.cf-square.light .coord { color: var(--board-dark); }
.cf-square.dark .coord { color: var(--board-light); }

.cf-square.sq-from::after, .cf-square.sq-to::after {
  content: ""; position: absolute; inset: 0;
  background: rgba(243, 200, 60, 0.42);
  box-shadow: inset 0 0 0 3px rgba(243, 156, 18, 0.5);
  pointer-events: none;
}
.cf-square.sq-check::before {
  content: ""; position: absolute; inset: 0;
  background: radial-gradient(circle, rgba(231, 76, 60, 0.85) 0%, rgba(231, 76, 60, 0) 72%);
  pointer-events: none;
}

.cf-piece {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  /* Scales with the square: JS sets --cf-piece-size from the board width. */
  font-size: var(--cf-piece-size, 6vmin);
  line-height: 1;
  z-index: 2;
  pointer-events: none;
  will-change: transform;
}
.cf-piece.white { color: #fdfdfd; text-shadow: 0 1px 1px rgba(0,0,0,0.35); -webkit-text-stroke: 1.2px #4a4a55; }
.cf-piece.black { color: #2a2a33; text-shadow: 0 1px 1px rgba(255,255,255,0.15); -webkit-text-stroke: 1.2px #0d0d14; }
.cf-piece.sliding { transition: transform 0.34s cubic-bezier(0.22, 1, 0.36, 1); }
.cf-piece.captured { animation: captureFade 0.3s ease forwards; }

@keyframes captureFade { to { opacity: 0; transform: scale(0.6); } }

.board-empty-hint {
  position: absolute;
  inset: 22px;
  display: grid;
  place-items: center;
  text-align: center;
  border-radius: 6px;
  background: rgba(15, 15, 30, 0.55);
  backdrop-filter: blur(2px);
  color: var(--text-secondary);
  font-size: 0.9rem;
  padding: 1.5rem;
  z-index: 5;
  transition: opacity 0.3s ease;
}
.board-empty-hint .big { font-size: 2rem; margin-bottom: 0.5rem; }

/* Board controls */
.board-controls {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  margin-top: 1rem;
}
.board-btn {
  flex: 1;
  display: grid;
  place-items: center;
  padding: 0.55rem 0;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 1rem;
  cursor: pointer;
  transition: var(--transition);
}
.board-btn:hover:not(:disabled) { color: var(--accent); border-color: var(--accent); background: rgba(243, 156, 18, 0.08); }
.board-btn:disabled { opacity: 0.35; cursor: not-allowed; }
.board-btn.play { flex: 1.3; background: linear-gradient(135deg, var(--accent), var(--accent-2)); color: #1a1a2e; border-color: transparent; }

.board-scrub { display: flex; align-items: center; gap: 0.75rem; margin-top: 0.85rem; }
.board-scrub input[type="range"] { flex: 1; }
.board-ply {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-secondary);
  white-space: nowrap;
  min-width: 64px;
  text-align: right;
}

.board-movecaption {
  text-align: center;
  margin-top: 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.92rem;
  color: var(--accent);
  min-height: 1.2rem;
}

/* Move list */
.move-list {
  margin-top: 1rem;
  max-height: 150px;
  overflow-y: auto;
  padding: 0.6rem 0.75rem;
  background: rgba(0, 0, 0, 0.22);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.9;
}
.move-list:empty { display: none; }
.move-list .move-no { color: var(--text-muted); margin-right: 0.2rem; }
.move-list .ply {
  display: inline-block;
  padding: 0.05rem 0.4rem;
  margin-right: 0.15rem;
  border-radius: 5px;
  color: var(--text-secondary);
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease;
}
.move-list .ply:hover { background: rgba(255, 255, 255, 0.08); color: var(--text-primary); }
.move-list .ply.current { background: linear-gradient(135deg, var(--accent), var(--accent-2)); color: #1a1a2e; font-weight: 700; }

/* ============================ Loading overlay ============================ */
.loading-overlay {
  position: fixed;
  inset: 0;
  background: rgba(8, 8, 20, 0.92);
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  backdrop-filter: blur(12px);
}
.loading-overlay.show { display: flex; }

.loader-board {
  display: grid;
  grid-template-columns: repeat(3, 26px);
  grid-template-rows: repeat(3, 26px);
  gap: 4px;
  margin-bottom: 1.75rem;
}
.loader-board span {
  border-radius: 5px;
  background: var(--accent);
  animation: loaderTile 1.4s ease-in-out infinite;
}
.loader-board span:nth-child(odd) { background: var(--accent-2); }
.loader-board span:nth-child(1) { animation-delay: 0s; }
.loader-board span:nth-child(2) { animation-delay: 0.1s; }
.loader-board span:nth-child(3) { animation-delay: 0.2s; }
.loader-board span:nth-child(4) { animation-delay: 0.3s; }
.loader-board span:nth-child(5) { animation-delay: 0.4s; }
.loader-board span:nth-child(6) { animation-delay: 0.5s; }
.loader-board span:nth-child(7) { animation-delay: 0.6s; }
.loader-board span:nth-child(8) { animation-delay: 0.7s; }
.loader-board span:nth-child(9) { animation-delay: 0.8s; }

@keyframes loaderTile {
  0%, 100% { transform: scale(0.55); opacity: 0.35; }
  50% { transform: scale(1); opacity: 1; }
}

.loading-text { font-family: var(--font-display); font-size: 1.25rem; color: var(--text-primary); margin: 0 0 0.4rem; }
.loading-sub { color: var(--text-secondary); font-size: 0.92rem; transition: opacity 0.3s ease; min-height: 1.3rem; }

.loading-bar {
  width: min(320px, 70vw);
  height: 5px;
  border-radius: 5px;
  background: rgba(255, 255, 255, 0.1);
  overflow: hidden;
  margin-top: 1.5rem;
}
.loading-bar::before {
  content: "";
  display: block;
  width: 40%;
  height: 100%;
  border-radius: 5px;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  animation: loadingSlide 1.4s ease-in-out infinite;
}
@keyframes loadingSlide {
  0% { transform: translateX(-110%); }
  100% { transform: translateX(280%); }
}

/* ============================ Video reveal ============================ */
.video-section { margin-top: 2rem; }
.video-container {
  position: relative;
  background: var(--glass-bg);
  backdrop-filter: blur(22px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--card-shadow);
  overflow: hidden;
}
.video-container::before {
  content: "";
  position: absolute; top: 0; left: 0; right: 0; height: 3px;
  background: linear-gradient(90deg, transparent, var(--accent), var(--accent-2), transparent);
}
.video-section.revealing .video-container { animation: videoReveal 0.7s cubic-bezier(0.22, 1, 0.36, 1); }
@keyframes videoReveal {
  from { opacity: 0; transform: scale(0.94) translateY(24px); }
  to { opacity: 1; transform: scale(1) translateY(0); }
}

.video-ready-head { text-align: center; margin-bottom: 1.5rem; }
.video-ready-head .badge-ready {
  display: inline-flex; align-items: center; gap: 0.5rem;
  font-size: 0.78rem; font-weight: 700; text-transform: uppercase; letter-spacing: 1.2px;
  color: var(--success);
  background: rgba(39, 174, 96, 0.12);
  border: 1px solid rgba(39, 174, 96, 0.3);
  padding: 0.3rem 0.9rem; border-radius: 50px; margin-bottom: 0.75rem;
}
.video-ready-head h3 { font-family: var(--font-display); font-size: 1.6rem; margin: 0; color: var(--text-primary); }
.video-caption { color: var(--text-secondary); font-size: 0.92rem; margin-top: 0.5rem; }
.video-caption strong { color: var(--accent); }

.video-wrapper {
  position: relative;
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: 0 16px 50px rgba(0, 0, 0, 0.5), 0 0 0 1px var(--glass-border);
  margin-bottom: 1.5rem;
  background: #000;
}
.video-wrapper video { width: 100%; display: block; }

.video-actions { display: flex; gap: 0.85rem; justify-content: center; flex-wrap: wrap; }

/* Sparkles on reveal */
.spark {
  position: absolute;
  width: 8px; height: 8px;
  background: var(--accent);
  border-radius: 50%;
  pointer-events: none;
  opacity: 0;
}
.video-section.revealing .spark { animation: sparkPop 0.9s ease-out forwards; }
@keyframes sparkPop {
  0% { opacity: 1; transform: scale(0) translateY(0); }
  100% { opacity: 0; transform: scale(1.4) translateY(-40px); }
}

/* ============================ Tip modal ============================ */
.tip-modal-overlay {
  position: fixed;
  inset: 0;
  z-index: 10000;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  background: rgba(8, 8, 20, 0.72);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}
.tip-modal-overlay.show { display: flex; animation: fadeIn 0.35s ease; }

.tip-modal {
  position: relative;
  width: 100%;
  max-width: 470px;
  background: linear-gradient(160deg, rgba(38, 38, 68, 0.94), rgba(15, 15, 30, 0.96));
  border: 1px solid var(--glass-border-strong);
  border-radius: var(--radius-lg);
  padding: 2.4rem 2rem 2rem;
  box-shadow: 0 30px 80px rgba(0, 0, 0, 0.6);
  text-align: center;
  overflow: hidden;
}
.tip-modal-overlay.show .tip-modal { animation: videoReveal 0.5s cubic-bezier(0.22, 1, 0.36, 1); }
.tip-modal::before {
  content: "";
  position: absolute; top: 0; left: 0; right: 0; height: 3px;
  background: linear-gradient(90deg, transparent, var(--accent), var(--accent-2), transparent);
}
.tip-emoji { font-size: 2.9rem; margin-bottom: 0.5rem; animation: logoFloat 5s ease-in-out infinite; }
.tip-modal h3 { font-family: var(--font-display); font-size: 1.42rem; margin: 0 0 0.95rem; color: var(--text-primary); }
.tip-modal p { color: var(--text-secondary); line-height: 1.7; margin: 0 0 0.85rem; font-size: 0.95rem; }
.tip-modal p strong { color: var(--accent); }
.tip-actions { display: flex; gap: 0.75rem; justify-content: center; flex-wrap: wrap; margin-top: 1.45rem; }

.tip-close {
  position: absolute;
  top: 0.65rem; right: 0.8rem;
  width: 34px; height: 34px;
  display: grid; place-items: center;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid var(--glass-border);
  border-radius: 50%;
  color: var(--text-secondary);
  font-size: 1.35rem; line-height: 1;
  cursor: pointer;
  transition: var(--transition);
}
.tip-close:hover { color: var(--text-primary); border-color: var(--accent); transform: rotate(90deg); }
.tip-close:focus-visible { outline: none; box-shadow: 0 0 0 3px rgba(243, 156, 18, 0.3); }

/* ============================ Alerts ============================ */
.alert {
  padding: 1rem 1.25rem;
  border-radius: var(--radius-sm);
  margin-top: 1.25rem;
  animation: slideDown 0.3s ease-out;
  font-size: 0.92rem;
}
.alert-danger { background: rgba(231, 76, 60, 0.12); border: 1px solid rgba(231, 76, 60, 0.35); color: #ff9a8c; }
.alert ul { margin: 0; padding-left: 1.2rem; }

/* ============================ Footer ============================ */
footer { text-align: center; padding: 3rem 1rem; color: var(--text-muted); font-size: 0.9rem; }
footer a { color: var(--accent); text-decoration: none; transition: var(--transition); }
footer a:hover { color: var(--accent-2); }
.heartbeat { color: #ff6b6b; animation: heartbeat 1.5s infinite; display: inline-block; }
@keyframes heartbeat {
  0% { transform: scale(1); } 25% { transform: scale(1.3); }
  40% { transform: scale(1); } 60% { transform: scale(1.3); } 100% { transform: scale(1); }
}

/* ============================ Animations / utils ============================ */
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes slideDown { from { opacity: 0; transform: translateY(-10px); } to { opacity: 1; transform: translateY(0); } }

.d-none { display: none !important; }
.visually-hidden {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0;
}

/* Scrollbar */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: var(--primary-darker); }
::-webkit-scrollbar-thumb { background: var(--accent); border-radius: 5px; }
::-webkit-scrollbar-thumb:hover { background: var(--accent-2); }

/* ============================ Responsive ============================ */
@media (max-width: 1000px) {
  .studio-grid { grid-template-columns: 1fr; }
  .studio-board-col { position: static; order: -1; }
  .board-frame { max-width: 460px; margin: 0 auto; }
  .board-controls, .board-scrub, .move-list, .board-movecaption { max-width: 460px; margin-left: auto; margin-right: auto; }
}

@media (max-width: 768px) {
  .main-container { padding: 1.1rem; }
  .glass-card { padding: 1.35rem; }
  .form-grid-2 { grid-template-columns: 1fr; }
  .preset-grid { grid-template-columns: 1fr; }
  .advanced-content { grid-template-columns: 1fr; padding: 1.1rem; }
  .tab-row { display: flex; }
  .tab-button { flex: 1; padding: 0.55rem 0.5rem; }
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
  .cf-piece.sliding { transition: none !important; }
}