@font-face {
  font-family: Inter;
  src: url("../assets/fonts/inter.woff2") format("woff2");
  font-weight: 100 900;
  font-display: swap;
}

:root {
  --ls-left-rail: 250px;
  --bg: #fafbfa;
  --rail: #ffffff;
  --canvas: #ffffff;
  --green: #12b981;
  --green-dark: #079b70;
  --ink: #0f1b2d;
  --muted: #8b939c;
  --line: #e8ebe9;
  --soft: #f4f7f5;
  --mint: #eaf8f3;
  --shadow-soft: 0 18px 48px rgba(15, 27, 45, 0.06);
  --shadow-button: 0 12px 28px rgba(18, 185, 129, 0.28);
  /* Visible viewport height + chrome reserved above/below the lesson circle. */
  --rt-viewport-h: 100vh;
  --rt-canvas-chrome: 292px;
  --rt-pad-x: 48px;
  --rt-pad-top: 36px;
  --rt-pad-bottom: 40px;
  --rt-header-h: 48px;
  --rt-header-mb: 18px;
  --rt-progress-mb: 28px;
  --rt-stage-gap: 28px;
}

@supports (height: 100dvh) {
  :root {
    --rt-viewport-h: 100dvh;
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  font-family: Inter, Arial, sans-serif;
  color: var(--ink);
  background: var(--bg);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

button {
  font: inherit;
  cursor: pointer;
}

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

button:focus-visible {
  outline: 3px solid rgba(18, 185, 129, 0.28);
  outline-offset: 3px;
}