*, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    .container{
      display: flex;
      flex-direction: column;
      align-items: center;
      margin-top: -50px;
    }

   body {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'Inter', sans-serif;
  overflow: hidden;

  background-image: url("bc calc.png");
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
}
.the{
  display: flex;
  justify-content: center;
  font-size: 30px;
  z-index: 5;
}

.heading{
  color: #dadae0;
  justify-content: center;
  z-index: 5;
  margin-bottom: 20px;
   font-family: "Viaoda Libre", serif;
  font-weight: 400;
  font-style: normal;
  font-size: 24px;
  background: #800080;  /* fallback for old browsers */
background: -webkit-linear-gradient(to right, #ffc0cb, #800080);  /* Chrome 10-25, Safari 5.1-6 */
background: linear-gradient(to right, #ffc0cb, #800080);

background-clip: text;
  -webkit-text-fill-color: transparent;
}

    /* Math background canvas */
    #math-bg {
      position: fixed;
      inset: 0;
      z-index: 0;
      pointer-events: none;
    }

    /* Blur overlay on top of the math canvas */
    .bg-blur {
      position: fixed;
      inset: 0;
      z-index: 1;
      backdrop-filter: blur(6px);
      -webkit-backdrop-filter: blur(6px);
      background: rgba(10, 10, 16, 0.55);
      pointer-events: none;
    }

    /* Colored ambient glows */
    .glow {
      position: fixed;
      border-radius: 50%;
      pointer-events: none;
      z-index: 1;
      filter: blur(80px);
    }
    .glow-purple {
      width: 500px; height: 500px;
      top: -100px; left: -100px;
      background: rgba(99, 102, 241, 0.15);
    }
    .glow-pink {
      width: 400px; height: 400px;
      bottom: -80px; right: -80px;
      background: rgba(236, 72, 153, 0.12);
    }
    .glow-teal {
      width: 300px; height: 300px;
      top: 50%; left: 60%;
      background: rgba(20, 184, 166, 0.10);
    }

    .calculator {
      position: relative;
      z-index: 2;
      width: 320px;
      background: rgba(22, 22, 34, 0.75);
      backdrop-filter: blur(24px);
      -webkit-backdrop-filter: blur(24px);
      border-radius: 28px;
      padding: 24px 20px 20px;
      border: 1px solid rgba(255, 255, 255, 0.10);
      box-shadow:
        0 32px 80px rgba(0, 0, 0, 0.7),
        0 0 0 1px rgba(255, 255, 255, 0.05) inset;
    }

    /* Display area */
    .display {
      background: #12121a;
      border-radius: 18px;
      padding: 18px 20px 14px;
      margin-bottom: 20px;
      min-height: 100px;
      display: flex;
      flex-direction: column;
      justify-content: flex-end;
      align-items: flex-end;
      border: 1px solid rgba(255, 255, 255, 0.05);
      overflow: hidden;
    }

    .display .expr {
      font-size: 14px;
      font-weight: 400;
      color: rgba(255, 255, 255, 0.35);
      min-height: 20px;
      word-break: break-all;
      text-align: right;
      margin-bottom: 6px;
      letter-spacing: 0.01em;
    }

    .display .result {
      font-size: 40px;
      font-weight: 300;
      color: #ffffff;
      word-break: break-all;
      text-align: right;
      letter-spacing: -0.02em;
      line-height: 1.1;
      transition: font-size 0.15s ease;
    }

    .display .result.small { font-size: 28px; }
    .display .result.xsmall { font-size: 20px; }

    /* Button grid */
    .buttons {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 10px;
    }

    /* Base button */
    .btn {
      height: 64px;
      border-radius: 16px;
      border: none;
      font-family: 'Inter', sans-serif;
      font-size: 18px;
      font-weight: 400;
      cursor: pointer;
      transition: transform 0.1s ease, filter 0.1s ease;
      outline: none;
      user-select: none;
      -webkit-tap-highlight-color: transparent;
    }

    .btn:active {
      transform: scale(0.93);
    }

    /* Number buttons */
    .btn.num {
      background: #252535;
      color: #ffffff;
      letter-spacing: -0.01em;
    }
    .btn.num:hover { filter: brightness(1.2); }

    /* Operator buttons */
    .btn.op {
      background: #2a2a40;
      color: #a5b4fc;
      font-size: 20px;
      font-weight: 500;
    }
    .btn.op:hover { filter: brightness(1.25); }

    /* Clear / utility */
    .btn.util {
      background: #2a2030;
      color: #f9a8d4;
      font-size: 16px;
      font-weight: 500;
    }
    .btn.util:hover { filter: brightness(1.25); }

    /* Equals button */
    .btn.eq {
      background: linear-gradient(135deg, #6366f1 0%, #818cf8 100%);
      color: #ffffff;
      font-size: 22px;
      font-weight: 500;
      box-shadow: 0 4px 20px rgba(99, 102, 241, 0.45);
    }
    .btn.eq:hover { filter: brightness(1.12); }
    .btn.eq:active { box-shadow: 0 2px 10px rgba(99, 102, 241, 0.3); }

    /* Zero spans two columns */
    .btn.zero {
      grid-column: span 2;
      text-align: left;
      padding-left: 26px;
      font-size: 18px;
    }