/* ==== Design Tokens ==== */
:root {
  /* Typography */
  --font-family: 'Inter', system-ui, -apple-system, sans-serif;
  --font-size-base: 16px;
  --font-weight-regular: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;

  /* Modern Color palette */
  --color-primary: hsl(180, 70%, 50%); /* teal */
  --color-primary-dark: hsl(180, 70%, 40%);
  --color-bg: hsl(210, 20%, 98%);
  --color-bg-dark: hsl(210, 20%, 10%);
  --color-surface: rgba(255, 255, 255, 0.25);
  --color-text: hsl(210, 10%, 20%);
  --color-text-light: hsl(210, 10%, 95%);

  /* Layout */
  --max-width: 430px;
  --border-radius: 16px;
  --gap: 1rem;
  --transition: 0.25s ease;
}

/* ==== Card Component ==== */
.card {
  background: var(--color-surface);
  backdrop-filter: blur(12px);
  border-radius: var(--border-radius);
  padding: calc(var(--gap) * 1.5);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12), 0 0 0 1px rgba(0,0,0,0.05);
  transition: var(--transition);
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.15), 0 0 0 1px rgba(0,0,0,0.07);
}

/* ==== Floating Action Buttons ==== */
.fab-container {
  position: fixed;
  bottom: var(--gap);
  right: var(--gap);
  display: flex;
  flex-direction: column;
  gap: var(--gap);
  z-index: 1000;
}
.fab {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--color-primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
  transition: var(--transition);
}
.fab:hover {
  background: var(--color-primary-dark);
  transform: translateY(-2px);
}

/* ==== Loading Overlay ==== */
.loading {
  position: fixed;
  inset: 0;
  background: rgba(255,255,255,0.8);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2000;
}
.loading.hidden {
  display: none;
}
.spinner {
  width: 48px;
  height: 48px;
  border: 4px solid var(--color-primary-light, #e0f2f1);
  border-top: 4px solid var(--color-primary);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}
@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

/* ==== Screen Transitions ==== */
.screen {
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}
.screen.active {
  opacity: 1;
  pointer-events: auto;
}

/* ==== Updated Icon Button for FAB (override defaults) ==== */


/* ==== Accessibility Focus ==== */
button:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 2px;
}

/* ==== Dark Mode Adjustments ==== */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: var(--color-bg-dark);
    --color-text: var(--color-text-light);
    --color-surface: rgba(0, 0, 0, 0.35);
  }
  html, body {
    background: linear-gradient(135deg, hsl(210, 20%, 12%), hsl(210, 15%, 8%));
  }
}
  /* Typography */
  --font-family: 'Inter', system-ui, -apple-system, sans-serif;
  --font-size-base: 16px;
  --font-weight-regular: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;

  /* Color palette */
  --color-primary: hsl(210, 85%, 55%); /* vibrant blue */
  --color-primary-dark: hsl(210, 85%, 45%);
  --color-bg: hsl(210, 20%, 98%);
  --color-bg-dark: hsl(210, 20%, 10%);
  --color-surface: rgba(255, 255, 255, 0.15);
  --color-text: hsl(210, 10%, 20%);
  --color-text-light: hsl(210, 10%, 95%);

  /* Layout */
  --max-width: 430px;
  --border-radius: 16px;
  --gap: 1rem;
  --transition: 0.25s ease;
}

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

html, body {
  height: 100%;
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  background: linear-gradient(135deg, hsl(210, 60%, 95%), hsl(210, 50%, 90%));
  color: var(--color-text);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

/* ==== Container ==== */
body {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--gap);
}

/* Central wrapper – limits width for mobile‑first designs */
.wrapper {
  width: 100%;
  max-width: var(--max-width);
}

/* ==== Card Component ==== */
.card {
  background: var(--color-surface);
  backdrop-filter: blur(12px);
  border-radius: var(--border-radius);
  padding: calc(var(--gap) * 1.5);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12);
  transition: var(--transition);
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.15);
}

.title {
  font-size: 1.75rem;
  font-weight: var(--font-weight-bold);
  margin-bottom: 0.5rem;
  color: var(--color-primary);
  text-align: center;
}

.subtitle {
  font-size: 1rem;
  font-weight: var(--font-weight-medium);
  margin-bottom: 1.5rem;
  text-align: center;
  color: var(--color-text);
}

/* ==== Control Groups ==== */
.control-group {
  margin-bottom: var(--gap);
}

.group-label {
  display: block;
  font-size: 0.9rem;
  font-weight: var(--font-weight-semibold);
  margin-bottom: 0.4rem;
  color: var(--color-text);
}

.button-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.option-btn {
  flex: 1 1 30%;
  background: var(--color-bg);
  border: 2px solid var(--color-primary);
  border-radius: var(--border-radius);
  padding: 0.5rem 0.75rem;
  font-weight: var(--font-weight-medium);
  color: var(--color-primary);
  cursor: pointer;
  transition: var(--transition);
  text-align: center;
}

.option-btn.active,
.option-btn:hover {
  background: var(--color-primary);
  color: #fff;
}

#bpm-slider {
  width: 100%;
}

.primary-btn {
  width: 100%;
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--border-radius);
  padding: 0.75rem 0;
  font-weight: var(--font-weight-bold);
  font-size: 1rem;
  cursor: pointer;
  transition: var(--transition);
  margin-top: var(--gap);
}

.primary-btn:hover {
  background: var(--color-primary-dark);
}

/* ==== Exercise Screen ==== */
.screen {
  display: none;
}

.screen.active {
  display: block;
}

.exercise-header {
  font-size: 0.95rem;
  font-weight: var(--font-weight-medium);
  text-align: center;
  margin-bottom: 0.75rem;
  color: var(--color-text);
}

.svg-grid {
  display: grid;
  gap: 0.75rem;
  justify-items: center;
  margin-bottom: var(--gap);
}

.control-bar {
  display: flex;
  justify-content: center;
  gap: 1rem;
}

.icon-btn {
  background: var(--color-bg);
  border: 2px solid var(--color-primary);
  border-radius: 50%;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  cursor: pointer;
  transition: var(--transition);
  color: var(--color-primary);
}

.hidden { display: none; }

/* Highlight active beat in SVG */
.active-beat {
  fill: var(--color-primary-dark);
  transform: scale(1.2);
  transition: var(--transition);
}

/* ==== Dark Mode (optional) ==== */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: var(--color-bg-dark);
    --color-text: var(--color-text-light);
    --color-surface: rgba(0, 0, 0, 0.35);
  }
  html, body {
    background: linear-gradient(135deg, hsl(210, 20%, 12%), hsl(210, 15%, 8%));
  }
}