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

:root {
    --bg-100: #ffffff;
    --bg-500: #f0f0f0;
    --bg-600: #e0e0e0;

    --fg-400: #3d3d3d;
    --fg-500: #333;

    --ft-sans: 'Open Sans', sans-serif;

    --ft-sans-wt-light: 300;
    --ft-sans-wt-normal: 400;
    --ft-sans-wt-bold: 600;
}

body {
    margin: 0;

    width: 100%;
    min-height: 100vh;

    font-family: var(--ft-sans);
    font-size: 16px;

    color: var(--fg-500);
    background: var(--bg-500);
}

//
// Structure
//

main {
    display: flex;
    flex-direction: column;

    align-items: center;

    gap: 1rem;

    header {
        width: 100%;

        display: flex;
        align-items: center;
        justify-content: center;

        padding: 0.5rem 1rem;
        gap: 0.75rem;

        background: var(--bg-100);
        border-bottom: 1px solid var(--bg-600);

        color: var(--fg-400);
        vertical-align: middle;

        .logo {
            font-size: 32px;
            font-weight: var(--ft-sans-wt-bold);
        }

        .machine {
            font-size: 24px;
            font-weight: var(--ft-sans-wt-normal);
        }
    }

    .widgets {
        display: flex;
        justify-content: center;
        align-items: start;

        flex-wrap: wrap;
        gap: 2rem;

        max-width: 120ch;

        .widget {
            background: var(--bg-100);
            border: 1px solid var(--bg-600);
            padding: 1rem;

            min-height: 10rem;
            max-width: 50ch;

            .title {
                font-weight: var(--ft-sans-wt-bold);

                code {
                    font-weight: normal;
                }
            }

            &.todo {
                width: 300px;
                height: 200px;
            }
        }
    }
}

//
// Typography
//

b {
    font-weight: var(--ft-sans-wt-bold);
}

p {
    margin: 0;

    & + p {
        margin-top: 0.5rem;
    }
}

$base-font-size: 16px;
$heading-scale: 1.33;

@function pow($number, $exponent) {
    $value: 1;

    @if $exponent > 0 {
        @for $i from 1 through $exponent {
            $value: $value * $number;
        }
    }

    @return $value;
}

@for $i from 1 through 5 {
    h#{$i} {
        margin: 0;

        $factor: pow($heading-scale, 5 - $i);
        font-size: $base-font-size * $factor;

        line-height: 1.5;
    }
}