These two scripts combined create CSS only triangles.

maths.scss

@function pow($number, $exp) {
  $value: 1;
  @if $exp > 0 {
    @for $i from 1 through $exp {
      $value: $value * $number;
    }
  }
  @else if $exp < 0 {
    @for $i from 1 through -$exp {
      $value: $value / $number;
    }
  }
  @return $value;
}

@function fact($number) {
  $value: 1;
  @if $number > 0 {
    @for $i from 1 through $number {
      $value: $value * $i;
    }
  }
  @return $value;
}

@function pi() {
  @return 3.14159265359;
}

@function rad($angle) {
  $unit: unit($angle);
  $unitless: $angle / ($angle * 0 + 1);
  // If the angle has 'deg' as unit, convert to radians.
  @if $unit == deg {
    $unitless: $unitless / 180 * pi();
  }
  @return $unitless;
}

@function sinus($angle) {
  $sin: 0;
  $angle: rad($angle);
  // Iterate a bunch of times.
  @for $i from 0 through 10 {
    $sin: $sin + pow(-1, $i) * pow($angle, (2 * $i + 1)) / fact(2 * $i + 1);
  }
  @return $sin;
}

@function cos($angle) {
  $cos: 0;
  $angle: rad($angle);
  // Iterate a bunch of times.
  @for $i from 0 through 10 {
    $cos: $cos + pow(-1, $i) * pow($angle, 2 * $i) / fact(2 * $i);
  }
  @return $cos;
}

@function tan($angle) {
  @return sin($angle) / cos($angle);
}

triangles.sass

/* 
    Calculations will be based on the following triangle 
           ^
          /|\
      C  / | \  B
        /  |  \ 
       ---------
           A

    Where B and C are always the same.
    */

// calculating function

@function calculate_lenght_C($width, $angle)
    $A_angle: 90 - $angle
    $B_angle: 90deg
    $C_angle: 180 - ($A_angle + $B_angle)

    $A_length: $width
    $B_length: $A_length * sinus($B_angle) / sinus($A_angle)
    $C_length: $B_length * sinus($C_angle) / sinus($A_angle)
    
    @debug $C_angle
    @debug $C_length
    
    @return $C_length

@mixin calculated_dimensions_triangle($width, $angle)
	width: 0
	height: 0
	border-left: $width solid transparent
	border-right: $width solid transparent
	border-bottom: calculate_lenght_C($width, $angle) solid

// how to use:
// @include calculated_dimensions_triangle(1920px, 90 - 45deg)
// border-bottom-color: red


// angles
$angle-white-triangle-left  : 4.623deg
$angle-white-triangle-right : 9.672deg

.white-triangle-holder
    height: 118px
    width: 100%
    position: absolute
    bottom: 0px
    &:before, &:after
        background-color: white
        position: absolute
        bottom: 0px
    &:before
        content: " "
        bottom: 0px
        @include calculated_dimensions_triangle(1920px, $angle-white-triangle-left)
    &:after
        content: " "
        bottom: 0px
    &.bottom
        &:after
    &.top
        &:before