/* ==========================================================================
   線性迴歸模型 (Linear Regression) CSS Design System
   Modern Dark Glassmorphism Theme
   ========================================================================== */

:root {
  --bg-dark: #0b0f19;
  --bg-card: rgba(18, 24, 38, 0.75);
  --bg-card-hover: rgba(26, 34, 54, 0.85);
  --border-glass: rgba(255, 255, 255, 0.1);
  --border-focus: rgba(56, 189, 248, 0.5);

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

  --accent-cyan: #38bdf8;
  --accent-cyan-glow: rgba(56, 189, 248, 0.35);
  --accent-purple: #c084fc;
  --accent-purple-glow: rgba(192, 132, 252, 0.35);
  --accent-emerald: #34d399;
  --accent-rose: #fb7185;

  --font-main: 'Inter', system-ui, -apple-system, sans-serif;
  --font-mono: 'Fira Code', monospace;
  
  --radius-lg: 16px;
  --radius-md: 12px;
  --radius-sm: 8px;
}

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

body {
  font-family: var(--font-main);
  background-color: var(--bg-dark);
  background-image: 
    radial-gradient(at 0% 0%, rgba(56, 189, 248, 0.12) 0px, transparent 50%),
    radial-gradient(at 100% 100%, rgba(192, 132, 252, 0.12) 0px, transparent 50%),
    radial-gradient(at 50% 50%, rgba(16, 185, 129, 0.05) 0px, transparent 50%);
  color: var(--text-primary);
  min-height: 100vh;
  padding: 24px;
  line-height: 1.5;
}

.app-container {
  max-width: 1320px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

/* --------------------------------------------------------------------------
   Header
   -------------------------------------------------------------------------- */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 4px;
}

.header-brand {
  display: flex;
  align-items: center;
  gap: 16px;
}

.logo-icon {
  width: 48px;
  height: 48px;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-purple));
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  box-shadow: 0 0 20px var(--accent-cyan-glow);
}

.app-header h1 {
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, #ffffff 30%, var(--accent-cyan));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.subtitle {
  font-size: 0.88rem;
  color: var(--text-secondary);
}

.badge-pulse {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(56, 189, 248, 0.1);
  border: 1px solid rgba(56, 189, 248, 0.3);
  color: var(--accent-cyan);
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 0.82rem;
  font-weight: 500;
}

.pulse-dot {
  width: 8px;
  height: 8px;
  background: var(--accent-cyan);
  border-radius: 50%;
  box-shadow: 0 0 8px var(--accent-cyan);
  animation: pulse-animation 1.5s infinite;
}

@keyframes pulse-animation {
  0% { transform: scale(0.95); opacity: 0.8; }
  50% { transform: scale(1.3); opacity: 1; }
  100% { transform: scale(0.95); opacity: 0.8; }
}

/* --------------------------------------------------------------------------
   Glassmorphism Cards
   -------------------------------------------------------------------------- */
.glass-card {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-lg);
  box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.glass-card:hover {
  border-color: rgba(255, 255, 255, 0.18);
}

/* --------------------------------------------------------------------------
   Metrics Grid
   -------------------------------------------------------------------------- */
.metrics-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.metric-card {
  padding: 16px 20px;
  display: flex;
  align-items: center;
  gap: 16px;
}

.metric-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.icon-purple { background: rgba(192, 132, 252, 0.15); color: var(--accent-purple); }
.icon-cyan { background: rgba(56, 189, 248, 0.15); color: var(--accent-cyan); }
.icon-emerald { background: rgba(52, 211, 153, 0.15); color: var(--accent-emerald); }
.icon-rose { background: rgba(251, 113, 133, 0.15); color: var(--accent-rose); }

.metric-content {
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.metric-label {
  font-size: 0.78rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-weight: 600;
}

.metric-value {
  font-size: 1.15rem;
  font-weight: 700;
  font-family: var(--font-mono);
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

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

.highlight-green { color: var(--accent-emerald); }
.highlight-rose { color: var(--accent-rose); }

/* --------------------------------------------------------------------------
   Main Workspace Layout
   -------------------------------------------------------------------------- */
.workspace-grid {
  display: grid;
  grid-template-columns: 1fr 380px;
  gap: 20px;
}

.panel-header {
  padding: 18px 22px;
  border-bottom: 1px solid var(--border-glass);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.panel-header h2 {
  font-size: 1.05rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text-primary);
}

/* --------------------------------------------------------------------------
   Canvas Panel
   -------------------------------------------------------------------------- */
.canvas-panel {
  display: flex;
  flex-direction: column;
}

.canvas-controls-inline {
  display: flex;
  align-items: center;
  gap: 12px;
}

.canvas-hint {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.canvas-wrapper {
  position: relative;
  width: 100%;
  padding: 16px;
  display: flex;
  justify-content: center;
  align-items: center;
  background: rgba(0, 0, 0, 0.2);
}

#scatter-canvas {
  background: #0d1322;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-glass);
  cursor: crosshair;
  width: 100%;
  max-width: 800px;
  height: auto;
  box-shadow: inset 0 0 20px rgba(0, 0, 0, 0.5);
}

.preset-bar {
  padding: 14px 22px;
  border-top: 1px solid var(--border-glass);
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.preset-title {
  font-size: 0.82rem;
  color: var(--text-muted);
  font-weight: 600;
}

/* --------------------------------------------------------------------------
   Control Panel & Sliders
   -------------------------------------------------------------------------- */
.control-panel {
  display: flex;
  flex-direction: column;
  padding: 20px;
  gap: 18px;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.control-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.custom-select {
  background: rgba(15, 23, 42, 0.8);
  border: 1px solid var(--border-glass);
  color: var(--text-primary);
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-family: var(--font-main);
  outline: none;
  cursor: pointer;
  transition: border-color 0.2s ease;
}

.custom-select:focus {
  border-color: var(--accent-cyan);
}

.hyperparam-box {
  display: flex;
  flex-direction: column;
  gap: 16px;
  background: rgba(0, 0, 0, 0.15);
  padding: 16px;
  border-radius: var(--radius-md);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.slider-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.slider-header {
  display: flex;
  justify-content: space-between;
  font-size: 0.82rem;
  color: var(--text-secondary);
}

.slider-val {
  font-family: var(--font-mono);
  color: var(--accent-cyan);
  font-weight: 600;
}

.custom-slider {
  -webkit-appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: rgba(255, 255, 255, 0.15);
  outline: none;
  cursor: pointer;
}

.custom-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--accent-cyan);
  box-shadow: 0 0 10px var(--accent-cyan-glow);
  cursor: pointer;
  transition: transform 0.1s ease;
}

.custom-slider::-webkit-slider-thumb:hover {
  transform: scale(1.25);
}

/* --------------------------------------------------------------------------
   Buttons
   -------------------------------------------------------------------------- */
.action-buttons {
  display: flex;
  gap: 10px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  font-size: 0.88rem;
  font-weight: 600;
  font-family: var(--font-main);
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.2s ease;
}

.btn-primary {
  background: linear-gradient(135deg, #0284c7, #0369a1);
  color: #ffffff;
  flex: 1;
}

.btn-glow {
  box-shadow: 0 0 15px rgba(2, 132, 199, 0.4);
}

.btn-glow:hover {
  background: linear-gradient(135deg, #38bdf8, #0284c7);
  box-shadow: 0 0 25px rgba(56, 189, 248, 0.6);
  transform: translateY(-1px);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-primary);
  border: 1px solid var(--border-glass);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.15);
}

.btn-preset {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-secondary);
  border: 1px solid rgba(255, 255, 255, 0.08);
  font-size: 0.8rem;
  padding: 6px 12px;
}

.btn-preset:hover {
  background: rgba(56, 189, 248, 0.15);
  color: var(--accent-cyan);
  border-color: rgba(56, 189, 248, 0.3);
}

.btn-sm {
  padding: 6px 12px;
  font-size: 0.8rem;
}

/* --------------------------------------------------------------------------
   Loss Chart Section
   -------------------------------------------------------------------------- */
.loss-chart-box {
  background: rgba(0, 0, 0, 0.25);
  border-radius: var(--radius-md);
  padding: 14px;
  border: 1px solid rgba(255, 255, 255, 0.05);
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.loss-chart-header {
  display: flex;
  justify-content: space-between;
  font-size: 0.82rem;
  color: var(--text-secondary);
  font-weight: 500;
}

.loss-epoch-counter {
  font-family: var(--font-mono);
  color: var(--accent-purple);
}

#loss-canvas {
  background: #090d16;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(255, 255, 255, 0.05);
  width: 100%;
  height: 140px;
}

/* Responsive adjustments */
@media (max-width: 1024px) {
  .workspace-grid {
    grid-template-columns: 1fr;
  }
  .metrics-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 640px) {
  .metrics-grid {
    grid-template-columns: 1fr;
  }
  .preset-bar {
    flex-direction: column;
    align-items: stretch;
  }
}