/* ============================================
   CHESSER — Main Design System & Global Styles
   ============================================ */

/* --- CSS Custom Properties (Design Tokens) --- */
:root {
  /* Background Palette (Warm Cozy Espresso/Cocoa) */
  --color-bg-primary: #120e0b;     /* Deep espresso/obsidian */
  --color-bg-secondary: #1b1511;   /* Rich dark cocoa */
  --color-bg-tertiary: #271f1a;    /* Muted warm wood */
  --color-bg-panel: rgba(27, 21, 17, 0.82);
  --color-bg-overlay: rgba(10, 8, 6, 0.85);

  /* Accent Palette — Classic Champagne Gold & Amber Glow */
  --color-accent-gold: #dfbd83;    /* Champagne Gold */
  --color-accent-amber: #eed4a0;   /* Creamy Amber Gold */
  --color-accent-gold-dim: #9c7b46; /* Hazelnut Gold */
  --color-accent-gold-glow: rgba(223, 189, 131, 0.28);

  /* Text Palette */
  --color-text-primary: #f8f6f0;   /* Alabaster cream white */
  --color-text-secondary: #baa696; /* Warm taupe gray */
  --color-text-dim: #7f6e62;       /* Cocoa gray */

  /* Board Palette */
  --color-board-light: #eed9c4;
  --color-board-dark: #8e684a;

  /* Highlight Palette */
  --color-highlight-move: rgba(223, 189, 131, 0.4);
  --color-highlight-selected: rgba(223, 189, 131, 0.6);
  --color-highlight-legal: rgba(100, 180, 100, 0.35);
  --color-highlight-check: rgba(220, 50, 50, 0.6);
  --color-highlight-last-move: rgba(223, 189, 131, 0.25);

  /* Semantic Colors */
  --color-success: #78c56d;
  --color-error: #db5c5c;
  --color-warning: #e8a94a;
  --color-info: #6da2db;

  /* Category Colors */
  --color-cat-abertura: #4a90d9;
  --color-cat-tatica: #d94a4a;
  --color-cat-final: #4abd7a;
  --color-cat-armadilha: #e8944a;
  --color-cat-defesa: #9a5ad9;
  --color-cat-estrategia: #5bbdd6;

  /* Typography */
  --font-display: 'Playfair Display', Georgia, serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Cascadia Code', 'Fira Code', monospace;

  /* Spacing Scale */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;

  /* Border Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 50%;

  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
  --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.6);
  --shadow-gold: 0 0 20px rgba(219, 178, 74, 0.30);
  --shadow-gold-lg: 0 0 40px rgba(219, 178, 74, 0.40);
  --shadow-inset: inset 0 2px 4px rgba(0, 0, 0, 0.3);

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.3s ease;
  --transition-slow: 0.5s ease;
  --transition-slower: 0.8s ease;

  /* Glass — more polished, more visible border */
  --glass-bg: rgba(27, 21, 17, 0.76);
  --glass-border: rgba(223, 189, 131, 0.18);
  --glass-blur: blur(14px);

  /* Z-index Scale */
  --z-base: 1;
  --z-dropdown: 100;
  --z-overlay: 500;
  --z-modal: 1000;
  --z-toast: 1500;

  /* Board sizing */
  --board-size: min(560px, 70vh);
}

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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
}


body {
  font-family: var(--font-body);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  line-height: 1.6;
  overflow: hidden;
  width: 100vw;
  height: 100vh;
  position: relative;
}

/* Subtle ambient glows on body */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    /* Deep space ambiance with suttle gold dust */
    radial-gradient(circle at 10% 20%, rgba(207, 171, 83, 0.05) 0%, transparent 40%),
    radial-gradient(circle at 90% 80%, rgba(207, 171, 83, 0.04) 0%, transparent 50%),
    radial-gradient(circle at 50% 50%, rgba(10, 13, 20, 0.4) 0%, transparent 100%);
  pointer-events: none;
  z-index: 0;
}

/* Vignette effect */
body::after {
  content: '';
  position: fixed;
  inset: 0;
  background: radial-gradient(ellipse at center, transparent 55%, rgba(0, 0, 0, 0.45) 100%);
  pointer-events: none;
  z-index: 0;
}

a {
  color: var(--color-accent-gold);
  text-decoration: none;
  transition: color var(--transition-fast);
}
a:hover {
  color: var(--color-accent-amber);
}

img, svg {
  display: block;
  max-width: 100%;
}

button {
  font-family: var(--font-body);
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
  font-size: inherit;
}

input, select, textarea {
  font-family: var(--font-body);
  color: var(--color-text-primary);
  background: var(--color-bg-tertiary);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-sm);
  padding: var(--space-sm) var(--space-md);
  font-size: 0.95rem;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}
input:focus, select:focus, textarea:focus {
  outline: none;
  border-color: var(--color-accent-gold);
  box-shadow: 0 0 0 3px var(--color-accent-gold-glow);
}

ul, ol {
  list-style: none;
}

/* Scrollbar Styling */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: var(--color-bg-secondary);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb {
  background: var(--color-accent-gold-dim);
  border-radius: 4px;
  transition: background var(--transition-fast);
}
::-webkit-scrollbar-thumb:hover {
  background: var(--color-accent-gold);
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-text-primary);
}

h1 { font-size: 2.5rem; letter-spacing: -0.02em; }
h2 { font-size: 2rem; letter-spacing: -0.01em; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.1rem; }
h6 { font-size: 1rem; }

.text-gold {
  color: var(--color-accent-gold);
}

.text-secondary {
  color: var(--color-text-secondary);
}

.text-dim {
  color: var(--color-text-dim);
}

.text-mono {
  font-family: var(--font-mono);
}

/* --- Layout Utilities --- */
#app {
  width: 100vw;
  height: 100vh;
  position: relative;
  z-index: var(--z-base);
  overflow: hidden;
}

.screen {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-slow), visibility var(--transition-slow);
  overflow: hidden;
}

.screen.active {
  opacity: 1;
  visibility: visible;
  z-index: 2;
}

.screen-content {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  padding: var(--space-lg);
}

/* --- Chess Pattern Background --- */
.bg-chess-pattern {
  background-image:
    /* Repeating 8×8-ish chess checkerboard */
    repeating-conic-gradient(
      rgba(219, 178, 74, 0.035) 0% 25%,
      transparent 0% 50%
    );
  background-size: 60px 60px;
}

/* --- Logo Glow --- */
.logo-glow {
  text-shadow:
    0 0 40px rgba(219, 178, 74, 0.35),
    0 0 80px rgba(219, 178, 74, 0.15),
    0 0 120px rgba(219, 178, 74, 0.08);
  position: relative;
}

/* --- Glass Panel --- polished with more visible borders */
.glass-panel {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md), inset 0 1px 0 rgba(255, 255, 255, 0.04);
}

.glass-panel-sm {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm), inset 0 1px 0 rgba(255, 255, 255, 0.04);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.95rem;
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
  white-space: nowrap;
}

.btn::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.1) 0%, transparent 50%);
  opacity: 0;
  transition: opacity var(--transition-fast);
}
.btn:hover::after {
  opacity: 1;
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-accent-gold), var(--color-accent-amber));
  color: var(--color-bg-primary);
  box-shadow: var(--shadow-sm), var(--shadow-gold);
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md), var(--shadow-gold-lg);
}
.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  background: var(--color-bg-tertiary);
  color: var(--color-text-primary);
  border: 1px solid var(--glass-border);
}
.btn-secondary:hover {
  background: rgba(58, 48, 40, 0.9);
  border-color: var(--color-accent-gold-dim);
  transform: translateY(-1px);
}

.btn-ghost {
  background: transparent;
  color: var(--color-text-secondary);
  border: 1px solid transparent;
}
.btn-ghost:hover {
  color: var(--color-accent-gold);
  background: rgba(219, 178, 74, 0.08);
  border-color: var(--glass-border);
}

.btn-danger {
  background: var(--color-error);
  color: #fff;
}
.btn-danger:hover {
  background: #c04040;
  transform: translateY(-1px);
}

.btn-icon {
  width: 40px;
  height: 40px;
  padding: 0;
  border-radius: var(--radius-full);
  font-size: 1.2rem;
}

.btn-lg {
  padding: var(--space-md) var(--space-xl);
  font-size: 1.1rem;
  border-radius: var(--radius-lg);
}

.btn-sm {
  padding: var(--space-xs) var(--space-md);
  font-size: 0.85rem;
  border-radius: var(--radius-sm);
}

.btn:disabled, .btn.disabled {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none !important;
}

/* --- Gold Border Accent --- */
.gold-border {
  border: 1px solid transparent;
  background-clip: padding-box;
  position: relative;
}
.gold-border::before {
  content: '';
  position: absolute;
  inset: -1px;
  border-radius: inherit;
  background: linear-gradient(135deg, var(--color-accent-gold), var(--color-accent-amber), var(--color-accent-gold-dim));
  z-index: -1;
  mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  mask-composite: exclude;
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  padding: 1px;
}

/* --- Badge --- */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 2px 10px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

.badge-gold {
  background: rgba(219, 178, 74, 0.15);
  color: var(--color-accent-gold);
  border: 1px solid rgba(219, 178, 74, 0.3);
}

.badge-success {
  background: rgba(109, 191, 103, 0.15);
  color: var(--color-success);
  border: 1px solid rgba(109, 191, 103, 0.3);
}

.badge-error {
  background: rgba(212, 84, 84, 0.15);
  color: var(--color-error);
  border: 1px solid rgba(212, 84, 84, 0.3);
}

.badge-warning {
  background: rgba(232, 169, 74, 0.15);
  color: var(--color-warning);
  border: 1px solid rgba(232, 169, 74, 0.3);
}

/* Category badges */
.badge-abertura { background: rgba(74, 144, 217, 0.15); color: var(--color-cat-abertura); border: 1px solid rgba(74, 144, 217, 0.3); }
.badge-tatica { background: rgba(217, 74, 74, 0.15); color: var(--color-cat-tatica); border: 1px solid rgba(217, 74, 74, 0.3); }
.badge-final { background: rgba(74, 189, 122, 0.15); color: var(--color-cat-final); border: 1px solid rgba(74, 189, 122, 0.3); }
.badge-armadilha { background: rgba(232, 148, 74, 0.15); color: var(--color-cat-armadilha); border: 1px solid rgba(232, 148, 74, 0.3); }
.badge-defesa { background: rgba(154, 90, 217, 0.15); color: var(--color-cat-defesa); border: 1px solid rgba(154, 90, 217, 0.3); }
.badge-estrategia { background: rgba(91, 189, 214, 0.15); color: var(--color-cat-estrategia); border: 1px solid rgba(91, 189, 214, 0.3); }

/* --- Divider --- */
.divider {
  width: 100%;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--glass-border), transparent);
  margin: var(--space-lg) 0;
}

/* --- Back Button --- */
.btn-back {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  font-weight: 500;
  border-radius: var(--radius-md);
  transition: all var(--transition-base);
  position: absolute;
  top: var(--space-lg);
  left: var(--space-lg);
  z-index: 10;
}
.btn-back:hover {
  color: var(--color-accent-gold);
  background: rgba(219, 178, 74, 0.08);
}
.btn-back .icon {
  font-size: 1.2rem;
  transition: transform var(--transition-fast);
}
.btn-back:hover .icon {
  transform: translateX(-3px);
}

/* --- Header bar with gold gradient bottom border --- */
.screen-header {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-lg) var(--space-2xl);
  position: relative;
  min-height: 72px;
  border-bottom: 1px solid transparent;
  background-image: linear-gradient(var(--color-bg-primary), var(--color-bg-primary)),
                    linear-gradient(90deg, transparent, var(--color-accent-gold-dim), var(--color-accent-gold), var(--color-accent-gold-dim), transparent);
  background-clip: padding-box, border-box;
  background-origin: padding-box, border-box;
}

.screen-header h2 {
  font-family: var(--font-display);
  font-size: 1.5rem;
  color: var(--color-accent-gold);
  padding: 0 90px;
  text-align: center;
  width: 100%;
}

/* --- Difficulty Stars --- */
.difficulty-stars {
  display: inline-flex;
  gap: 2px;
}
.difficulty-stars .star {
  font-size: 0.8rem;
  color: var(--color-text-dim);
}
.difficulty-stars .star.filled {
  color: var(--color-accent-gold);
}

/* --- Toggle Switch --- */
.toggle-switch {
  position: relative;
  width: 48px;
  height: 26px;
  flex-shrink: 0;
}
.toggle-switch input {
  opacity: 0;
  width: 0;
  height: 0;
  position: absolute;
}
.toggle-slider {
  position: absolute;
  inset: 0;
  background-color: var(--color-bg-tertiary);
  border: 1px solid var(--glass-border);
  border-radius: 26px;
  cursor: pointer;
  transition: all var(--transition-base);
}
.toggle-slider::before {
  content: '';
  position: absolute;
  width: 20px;
  height: 20px;
  left: 2px;
  bottom: 2px;
  background: var(--color-text-dim);
  border-radius: var(--radius-full);
  transition: all var(--transition-base);
}
.toggle-switch input:checked + .toggle-slider {
  background: linear-gradient(135deg, var(--color-accent-gold), var(--color-accent-amber));
  border-color: var(--color-accent-gold);
}
.toggle-switch input:checked + .toggle-slider::before {
  transform: translateX(22px);
  background: var(--color-bg-primary);
}

/* --- Range Slider --- */
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  background: var(--color-bg-tertiary);
  border-radius: 3px;
  outline: none;
  border: none;
  padding: 0;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 20px;
  height: 20px;
  border-radius: var(--radius-full);
  background: linear-gradient(135deg, var(--color-accent-gold), var(--color-accent-amber));
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
  transition: transform var(--transition-fast);
}
input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.15);
}
input[type="range"]::-moz-range-thumb {
  width: 20px;
  height: 20px;
  border-radius: var(--radius-full);
  background: linear-gradient(135deg, var(--color-accent-gold), var(--color-accent-amber));
  cursor: pointer;
  border: none;
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
}

/* --- Modal / Overlay --- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: var(--color-bg-overlay);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: var(--z-modal);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-base);
}
.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}

/* Confirm modal must stack above all other modals */
#confirm-modal.active {
  z-index: 1200;
}

.modal-content {
  background: var(--color-bg-secondary);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  max-width: 440px;
  width: 90%;
  box-shadow: var(--shadow-xl);
  transform: scale(0.9) translateY(20px);
  transition: transform var(--transition-base);
}
.modal-overlay.active .modal-content {
  transform: scale(1) translateY(0);
}

.modal-title {
  font-family: var(--font-display);
  font-size: 1.3rem;
  color: var(--color-accent-gold);
  margin-bottom: var(--space-md);
}

.modal-actions {
  display: flex;
  gap: var(--space-md);
  justify-content: flex-end;
  margin-top: var(--space-lg);
}

/* --- Toast Notification --- */
.toast-container {
  position: fixed;
  top: var(--space-lg);
  right: var(--space-lg);
  z-index: var(--z-toast);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.toast {
  background: var(--color-bg-secondary);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: var(--space-md) var(--space-lg);
  box-shadow: var(--shadow-lg);
  color: var(--color-text-primary);
  font-size: 0.9rem;
  transform: translateX(120%);
  transition: transform var(--transition-base);
  max-width: 360px;
}
.toast.show {
  transform: translateX(0);
}
.toast.toast-success { border-left: 3px solid var(--color-success); }
.toast.toast-error { border-left: 3px solid var(--color-error); }
.toast.toast-warning { border-left: 3px solid var(--color-warning); }

/* --- Loading Spinner --- */
.spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--color-bg-tertiary);
  border-top-color: var(--color-accent-gold);
  border-radius: var(--radius-full);
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.loading-screen {
  position: fixed;
  inset: 0;
  background: var(--color-bg-primary);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-lg);
  z-index: 9999;
  transition: opacity var(--transition-slow);
}
.loading-screen.hidden {
  opacity: 0;
  pointer-events: none;
}

/* --- Utility Classes --- */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.flex-between { display: flex; align-items: center; justify-content: space-between; }
.gap-sm { gap: var(--space-sm); }
.gap-md { gap: var(--space-md); }
.gap-lg { gap: var(--space-lg); }
.gap-xl { gap: var(--space-xl); }
.w-full { width: 100%; }
.h-full { height: 100%; }
.relative { position: relative; }
.overflow-hidden { overflow: hidden; }
.text-center { text-align: center; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

/* Selection styling */
::selection {
  background: var(--color-accent-gold);
  color: var(--color-bg-primary);
}

/* ============================================
   CHESSER — Theme Implementations
   Premium themes are securely fetched and loaded dynamically from the backend themes directory.
   ============================================ */