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

body {
  font: 12px sans-serif;
  height: 100vh;
  width: 100vw;
  padding: 1em 50px;
}

/* graph */
#graph-f, #graph-df {
  margin: 1em 0;
  width: calc(100%);
}

.rules line, .rules path {
  shape-rendering: crispEdges;
}

text {
  font-size: 1.2em;
}

.rules .minor {
  stroke: #BBB;
}

.rules .domain {
  fill: none;
}

.grid .tick line {
  stroke: #CCC;
}

.series path {
  fill: none;
  stroke: #AE81FF;
  stroke-width: 3px;
}

.x_axis {
  stroke: #000;
  stroke-width: 2;
}

.subdiv-point {
  fill: red;
  r: 3px;
}

.sample-point {
  fill: #1a69b5;
  r: 4px;
}

rect.riemann {
  fill: #1a69b580;
  stroke: #1a69b5;
  stroke-width: 1.5px;
}

.tangent {
  stroke: orange;
  stroke-width: 5px;
}

.piecewise {
  fill: none;
  stroke: #FF0080;
  stroke-width: 2px;
}

form {
  font-size: 2em;
  margin: -.5em auto 1.5em;
  text-align: center;
  vertical-align: middle;
}

form > * {
  vertical-align: middle;
}

input[type="button"] {
  font-size: 1em;
}