/* ==========================================================================
   DigitalED Gradient Descent 3D - Design System & Modern Stylesheet
   ========================================================================== */

:root {
  --bg-dark: #0a0d14;
  --bg-sidebar: rgba(13, 17, 27, 0.88);
  --bg-card: rgba(21, 28, 44, 0.7);
  --bg-card-hover: rgba(29, 39, 61, 0.85);
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-focus: rgba(0, 242, 254, 0.5);

  --accent-cyan: #00f2fe;
  --accent-blue: #4facfe;
  --accent-emerald: #10b981;
  --accent-amber: #f59e0b;
  --accent-rose: #f43f5e;
  --accent-purple: #a855f7;

  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  --shadow-glow: 0 0 20px rgba(0, 242, 254, 0.25);
  --shadow-card: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
  --transition-fast: 0.18s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 0.28s cubic-bezier(0.16, 1, 0.3, 1);
}

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

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg-dark);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 14px;
  line-height: 1.45;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Master Layout: 25% max left column, 75% right 3D visualizer */
.app-container {
  display: flex;
  width: 100vw;
  height: 100vh;
  position: relative;
  overflow: hidden;
}

/* ==========================================================================
   LEFT COLUMN (NARROW: MAX 25% OF PAGE)
   ========================================================================== */
.sidebar {
  flex: 0 0 25%;
  width: 25vw;
  max-width: 25%;
  min-width: 310px;
  height: 100vh;
  background: var(--bg-sidebar);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-right: 1px solid var(--border-subtle);
  display: flex;
  flex-direction: column;
  z-index: 20;
  box-shadow: 4px 0 24px rgba(0, 0, 0, 0.4);
  position: relative;
}

.sidebar-header {
  padding: 16px 18px 12px;
  border-bottom: 1px solid var(--border-subtle);
  background: rgba(10, 13, 20, 0.4);
}

.brand-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 6px;
}

.brand-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.brand-icon {
  font-size: 18px;
  -webkit-text-fill-color: initial;
}

.score-banner {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 6px 10px;
  background: rgba(16, 185, 129, 0.1);
  border: 1px solid rgba(16, 185, 129, 0.25);
  border-radius: var(--radius-sm);
  font-size: 12px;
  font-weight: 600;
}

.score-pill, .runs-pill {
  display: flex;
  align-items: center;
  gap: 4px;
}
.score-pill span, .runs-pill span {
  font-family: var(--font-mono);
  color: #34d399;
}

/* Scrollable controls panel */
.sidebar-scroll {
  flex: 1 1 auto;
  overflow-y: auto;
  overflow-x: hidden;
  padding: 14px 16px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.sidebar-scroll::-webkit-scrollbar {
  width: 5px;
}
.sidebar-scroll::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.15);
  border-radius: 4px;
}

/* Control Cards */
.control-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 12px 14px;
  transition: border-color var(--transition-fast), background var(--transition-fast);
}

.control-card:hover {
  border-color: rgba(255, 255, 255, 0.14);
}

.card-title-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 10px;
}

.card-title {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 6px;
}

.help-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 17px;
  height: 17px;
  border-radius: var(--radius-full);
  background: rgba(255, 255, 255, 0.1);
  color: var(--accent-cyan);
  font-size: 11px;
  font-weight: 700;
  cursor: help;
  transition: transform var(--transition-fast), background var(--transition-fast);
}
.help-icon:hover {
  transform: scale(1.15);
  background: rgba(0, 242, 254, 0.25);
}

/* Challenge Level Card */
.challenge-card {
  border-left: 3px solid var(--accent-amber);
  background: linear-gradient(135deg, rgba(245, 158, 11, 0.08), rgba(21, 28, 44, 0.8));
}
.challenge-title {
  font-size: 13px;
  font-weight: 700;
  color: var(--accent-amber);
  margin-bottom: 4px;
}
.challenge-obj {
  font-size: 12px;
  color: var(--text-primary);
  margin-bottom: 6px;
}
.challenge-hint {
  font-size: 11px;
  color: var(--text-muted);
  font-style: italic;
}

/* Forms & Parameter Sliders */
.param-group {
  margin-bottom: 12px;
}
.param-group:last-child {
  margin-bottom: 0;
}

.param-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 5px;
}

.param-label {
  font-size: 12px;
  font-weight: 500;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 4px;
  cursor: pointer;
}

.param-val {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--accent-cyan);
  font-weight: 600;
  background: rgba(0, 242, 254, 0.1);
  padding: 1px 6px;
  border-radius: 4px;
}

/* Custom Range Slider */
input[type="range"] {
  -webkit-appearance: none;
  width: 100%;
  height: 6px;
  border-radius: var(--radius-full);
  background: rgba(255, 255, 255, 0.12);
  outline: none;
  cursor: pointer;
  transition: background var(--transition-fast);
}

input[type="range"]:hover {
  background: rgba(255, 255, 255, 0.18);
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 16px;
  height: 16px;
  border-radius: var(--radius-full);
  background: var(--accent-cyan);
  cursor: pointer;
  box-shadow: 0 0 10px rgba(0, 242, 254, 0.6);
  transition: transform var(--transition-fast), background var(--transition-fast);
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.2);
  background: #ffffff;
}

/* Select and inputs */
select, .select-styled {
  width: 100%;
  background: rgba(10, 14, 23, 0.85);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  padding: 7px 10px;
  font-size: 12px;
  font-family: var(--font-sans);
  outline: none;
  cursor: pointer;
  transition: border-color var(--transition-fast);
}
select:focus {
  border-color: var(--accent-cyan);
}

/* Optimizer Radio Pill Grid */
.optimizer-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 6px;
  margin-top: 6px;
}

.optimizer-radio-label {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 6px 4px;
  font-size: 11px;
  font-weight: 600;
  background: rgba(10, 14, 23, 0.6);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-align: center;
}

.optimizer-radio-label input {
  display: none;
}

.optimizer-radio-label:hover {
  background: rgba(255, 255, 255, 0.06);
  border-color: rgba(255, 255, 255, 0.16);
}

.optimizer-radio-label:has(input:checked) {
  background: rgba(0, 242, 254, 0.15);
  border-color: var(--accent-cyan);
  color: var(--accent-cyan);
  box-shadow: 0 0 10px rgba(0, 242, 254, 0.2);
}

.formula-info-badge {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--text-muted);
  margin-top: 6px;
  text-align: center;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* Primary Action Buttons */
.btn-primary {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 10px 14px;
  background: linear-gradient(135deg, #00f2fe 0%, #4facfe 100%);
  color: #031024;
  border: none;
  border-radius: var(--radius-md);
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  box-shadow: 0 4px 16px rgba(0, 242, 254, 0.35);
}

.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 22px rgba(0, 242, 254, 0.5);
}

.btn-primary:active {
  transform: translateY(1px);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 12px;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.14);
  border-color: rgba(255, 255, 255, 0.2);
}

.action-buttons-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin-top: 8px;
}

/* Random Surface Button */
.btn-random {
  background: linear-gradient(135deg, rgba(168, 85, 247, 0.2), rgba(79, 172, 254, 0.2));
  border: 1px solid rgba(168, 85, 247, 0.4);
  color: #e9d5ff;
}
.btn-random:hover {
  background: linear-gradient(135deg, rgba(168, 85, 247, 0.35), rgba(79, 172, 254, 0.35));
  border-color: var(--accent-purple);
}

/* Sidebar Footer */
.sidebar-footer {
  padding: 10px 16px;
  border-top: 1px solid var(--border-subtle);
  font-size: 11px;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(10, 13, 20, 0.5);
}

.session-indicator {
  display: flex;
  align-items: center;
  gap: 6px;
}
.session-dot {
  width: 7px;
  height: 7px;
  border-radius: var(--radius-full);
  background: #10b981;
  box-shadow: 0 0 8px #10b981;
}

/* ==========================================================================
   RIGHT AREA: 3D VISUALIZER CANVAS (~75% OF PAGE)
   ========================================================================== */
.visualizer-area {
  flex: 1 1 75%;
  height: 100vh;
  position: relative;
  overflow: hidden;
  background: var(--bg-dark);
}

#canvas-container {
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
}

#graph2d-container {
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
  background: var(--bg-dark);
}

/* Floating Top HUD over 3D Canvas */
.canvas-hud-top {
  position: absolute;
  top: 16px;
  left: 20px;
  right: 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  pointer-events: none;
  z-index: 10;
}

.hud-group {
  display: flex;
  align-items: center;
  gap: 10px;
  pointer-events: auto;
}

/* 2D / 3D Mode Toggle Pill */
.mode-toggle-pill {
  display: inline-flex;
  background: rgba(13, 17, 27, 0.85);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  padding: 3px;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: var(--shadow-card);
}

.mode-toggle-btn {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  font-size: 12px;
  font-weight: 600;
  padding: 6px 14px;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.mode-toggle-btn.active {
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  color: #031024;
  box-shadow: 0 2px 10px rgba(0, 242, 254, 0.35);
}

/* HUD Telemetry Card */
.hud-telemetry-card {
  background: rgba(13, 17, 27, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  padding: 6px 16px;
  display: flex;
  align-items: center;
  gap: 16px;
  font-size: 12px;
  box-shadow: var(--shadow-card);
}

.telemetry-item {
  display: flex;
  align-items: center;
  gap: 5px;
}
.telemetry-label {
  color: var(--text-muted);
  font-weight: 500;
}
.telemetry-val {
  font-family: var(--font-mono);
  font-weight: 600;
  color: var(--accent-cyan);
}

/* Status Pill */
.status-pill {
  padding: 3px 10px;
  border-radius: var(--radius-full);
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.status-ready { background: rgba(100, 116, 139, 0.25); color: #94a3b8; }
.status-running { background: rgba(0, 242, 254, 0.2); color: #00f2fe; animation: pulseGlow 1.4s infinite; }
.status-success { background: rgba(16, 185, 129, 0.25); color: #10b981; }
.status-danger { background: rgba(244, 63, 94, 0.25); color: #f43f5e; }
.status-warning { background: rgba(245, 158, 11, 0.25); color: #f59e0b; }
.status-info { background: rgba(56, 189, 248, 0.25); color: #38bdf8; }

@keyframes pulseGlow {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.55; }
}

/* Canvas Floating Bottom HUD */
.canvas-hud-bottom {
  position: absolute;
  bottom: 20px;
  left: 20px;
  right: 20px;
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  pointer-events: none;
  z-index: 10;
}

.surface-info-plate {
  pointer-events: auto;
  background: rgba(13, 17, 27, 0.85);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 10px 14px;
  max-width: 380px;
  box-shadow: var(--shadow-card);
}

.surface-title-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 4px;
}
.surface-name {
  font-size: 13px;
  font-weight: 700;
  color: var(--text-primary);
}
.formula-badge {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--accent-cyan);
  background: rgba(0, 242, 254, 0.1);
  padding: 2px 6px;
  border-radius: 4px;
}
.surface-desc {
  font-size: 11px;
  color: var(--text-secondary);
  line-height: 1.4;
}

.hud-click-prompt {
  font-size: 11px;
  color: #34d399;
  margin-top: 4px;
  display: flex;
  align-items: center;
  gap: 4px;
}

/* Quick Tools Pill (Bottom Right) */
.hud-tools-plate {
  pointer-events: auto;
  background: rgba(13, 17, 27, 0.85);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  padding: 5px 12px;
  display: flex;
  align-items: center;
  gap: 12px;
  box-shadow: var(--shadow-card);
}

.toggle-label {
  display: flex;
  align-items: center;
  gap: 5px;
  font-size: 11px;
  color: var(--text-secondary);
  cursor: pointer;
  user-select: none;
}
.toggle-label input {
  accent-color: var(--accent-cyan);
  cursor: pointer;
}

.btn-icon {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  font-size: 14px;
  cursor: pointer;
  padding: 4px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: color var(--transition-fast);
}
.btn-icon:hover {
  color: var(--text-primary);
}

/* ==========================================================================
   HOVER EXPLANATION TOOLTIP CARD
   ========================================================================== */
.educational-tooltip-card {
  position: fixed;
  width: 320px;
  background: rgba(13, 17, 27, 0.94);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border: 1px solid rgba(0, 242, 254, 0.35);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.6), 0 0 20px rgba(0, 242, 254, 0.2);
  z-index: 1000;
  pointer-events: none;
  opacity: 0;
  transform: translateY(6px);
  transition: opacity var(--transition-fast), transform var(--transition-fast);
}

.educational-tooltip-card.visible {
  opacity: 1;
  transform: translateY(0);
}

.tooltip-header {
  margin-bottom: 8px;
}
.tooltip-title {
  font-size: 13px;
  font-weight: 700;
  color: #ffffff;
  display: flex;
  align-items: center;
  gap: 6px;
}
.tooltip-formula {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--accent-cyan);
  background: rgba(0, 242, 254, 0.08);
  padding: 2px 6px;
  border-radius: 4px;
  margin-top: 4px;
  display: inline-block;
}

.tooltip-concept {
  font-size: 12px;
  color: var(--text-secondary);
  margin-bottom: 10px;
  line-height: 1.4;
}

.tooltip-split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin-bottom: 10px;
}
.tooltip-box {
  background: rgba(0, 0, 0, 0.3);
  padding: 8px;
  border-radius: var(--radius-sm);
  font-size: 11px;
  line-height: 1.35;
}
.tooltip-box-low { border-left: 2px solid var(--accent-amber); }
.tooltip-box-high { border-left: 2px solid var(--accent-rose); }
.box-tag {
  font-weight: 700;
  font-size: 10px;
  text-transform: uppercase;
  margin-bottom: 2px;
}
.tooltip-box-low .box-tag { color: var(--accent-amber); }
.tooltip-box-high .box-tag { color: var(--accent-rose); }

.tooltip-analogy {
  font-size: 11px;
  color: #38bdf8;
  font-style: italic;
  background: rgba(56, 189, 248, 0.08);
  padding: 6px 8px;
  border-radius: 4px;
}

/* Notification Banner */
.app-notification {
  position: fixed;
  top: 24px;
  right: 24px;
  background: rgba(13, 17, 27, 0.95);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 12px 18px;
  font-size: 13px;
  font-weight: 600;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  z-index: 2000;
  opacity: 0;
  transform: translateY(-10px);
  pointer-events: none;
  transition: all var(--transition-smooth);
}
.app-notification.visible {
  opacity: 1;
  transform: translateY(0);
}
.notification-success { border-color: var(--accent-emerald); color: #34d399; }
.notification-warning { border-color: var(--accent-amber); color: #fbbf24; }
.notification-danger { border-color: var(--accent-rose); color: #f43f5e; }
.notification-info { border-color: var(--accent-cyan); color: #38bdf8; }