@font-face {
    font-family: "STIX Two Math";
    src: url('/fonts/STIXTwoMath-Regular.ttf');
}
:root {
    --text-color: #222;
    --link-color: #007bff;
    --link-hover-color: #0056b3;
    --secondary-link-color: #6c757d;
    --secondary-link-hover-color: #5a6268;

    --primary-button-border-color: #007bff;
    --primary-button-hover-border-color: #0056b3;

    --secondary-button-border-color: #6c757d;
    --secondary-button-hover-border-color: #5a6268;

    --background-color: #f8f9fa;
    --secondary-background-color: #e9ecef;
}

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

html {
    height: 100%;
}

body {
    color: #222;
    font-size: 16px;
    line-height: 1.5em;
    font-family: system-ui, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
    display: flex;
    height: 100%;
    flex-direction: column;
    margin: 0;
    padding: 0;
    max-width: 100%;
}

button, input {
    font-family: inherit;
    font-size: 100%;
    line-height: 1.15em;
    margin: 0;
}

button, input[type=submit] {
    cursor: pointer;
    border-style: none;
}

header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1.5em 0;
    margin: 0 0 1em;
    border-bottom: 1px solid #dee2e6;

    .main-link {
        margin-right: auto;
        text-decoration: none;
        color: var(--text-color);
        font-size: 1.75em;
    }
}

nav > ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: inline-flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    width: fit-content;

    li {
        margin: 0;
        padding-right: 1em;
        padding-left: 1em;
    }

}

.nav-link {
    color: var(--link-color);
    text-decoration: none;

    &.active {
        color: var(--secondary-link-color);
    }

    &:visited {
        color: inherit;
    }

}

main {
    flex-shrink: 0;
    margin-bottom: 1em;
}

.container {
    margin-left: auto;
    margin-right: auto;
    width: 100%;
    padding-left: 1em;
    padding-right: 1em;

    @media screen and (min-width: 576px) {
        max-width: 540px;
    }

    @media screen and (min-width: 768px) {
        max-width: 720px;
    }

    @media screen and (min-width: 992px) {
        max-width: 970px;
    }

    @media screen and (min-width: 1200px) {
        max-width: 1170px;
    }

    @media screen and (min-width: 1400px) {
        max-width: 1370px;
    }
}

#solutions-list > p > math {
    font-size: 1.5em;
}

#show-solutions, #hide-solutions {
    margin-left: 1em;
    touch-action: manipulation;
}

input[type=number] {
    width: 5em;
    display: inline-block;
    -moz-appearance: textfield;
    line-height: 2em;
    padding: 0.375em;
    border-radius: 5px;
    border: 1px solid var(--secondary-button-border-color);
    margin-top: 0.25em;
    margin-bottom: 0.25em;
    font-size: 1em;
}

input[type=number]::-webkit-outer-spin-button,
input[type=number]::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.btn {
    touch-action: manipulation;
    padding: 0.5em 1em;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    cursor: pointer;
    border-radius: 0.5em;
    font-size: 1em;
    color: white;
    font-weight: 400;

    &.btn-primary {
        background-color: var(--link-color);
        border-color: var(--primary-button-border-color);

        &:hover {
            background-color: var(--link-hover-color);
            border-color: var(--primary-button-hover-border-color);
        }
    }

    &.btn-secondary {
        background-color: var(--secondary-link-color);
        border-color: var(--secondary-button-border-color);

        &:hover {
            background-color: var(--secondary-link-hover-color);
            border-color: var(--secondary-button-hover-border-color);
        }
    }

    &.btn-small {
        padding: 0.25em 0.5em;
        font-size: 0.8em;
    }
}

footer {
    margin-top: auto;
    padding-top: 1em;
    padding-bottom: 1em;
    background-color: var(--secondary-background-color);
    margin-left: 0;
    margin-right: 0;
}

.footer-content {
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: space-between;

    a {
        text-decoration: none;
        color: var(--text-color);

        &:hover {
            text-decoration: underline;
        }
    }
}

.footer-links {
    display: inline-flex;
    gap: 1em;
    flex-direction: row;
    align-items: center;
    justify-content: flex-start;

}

input:where([type="checkbox"][role="switch"]) {
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    position: relative;
    font-size: inherit;
    width: 2em;
    height: 1em;
    box-sizing: content-box;
    border: 1px solid gray;
    border-radius: 1em;
    vertical-align: text-bottom;
    margin: auto;
    user-select: none;
    touch-action: manipulation;
    background-color: var(--background-color);
    transition: transform 0.2s linear;

    &::before {
        content: "";
        position: absolute;
        top: 50%;
        left: 0;
        transform: translate(0, -50%);
        box-sizing: border-box;
        width: 0.8em;
        height: 0.8em;
        margin: 0 0.1em;
        border: 1px solid;
        border-radius: 50%;
        background-color: white;
    }

    &:active {
        opacity: 0.6;
    }

    &:checked::before {
        left: 1em;
    }

    &:checked {
        background-color: var(--link-color);
    }
}

.alert {
    font-style: italic;
    margin: 1em 0;
    padding: 0.5em 1em;

    &.alert-error {
        background-color: #f8d7da;
        border: 0.15em solid #f5c6cb;
        color: #721c24;
    }

    &.alert-warning {
        background-color: #fff3cd;
        border: 0.15em solid #ffeeba;
        color: #856404;
    }

    &.alert-success {
        background-color: #d4edda;
        border: 0.15em solid #c3e6cb;
        color: #155724;
    }

    &::first-line {
        font-weight: bold;
    }
}

.default-hidden {
    display: none;
}

h1, h2, h3, h4, h5, h6 {
    margin-top: 1em;
    margin-bottom: 0.5em;
    font-weight: 500;
}

math {
    font-family: "STIX Two Math", math;
}

.inline-math {
    display: inline-block;
    white-space: nowrap;
}

.inline-math mn {
    margin-right: 0.5em;
}

.inline-math mn:last-child {
    margin-right: 0;
}

.game-rules {
    margin-top: 1em;
    padding: 1em 1em 1em 0.5em;
    width: 100%;
    background-color: var(--secondary-background-color);
}

.solvability-prompt {
    display: inline-flex;
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
}

.solvability-prompt > label {
    margin-left: 0.5em;
}

.rule-section {
    margin-top: 1em;
    margin-bottom: 1em;
}

.rule-title {
    font-weight: bold;
}

.rule-input {
    margin-left: 1em;
}

.rule-input.rule-input-checkboxes {
    @media screen and (min-width: 576px) {
        display: block;
    }
    @media screen and (min-width: 1400px) {
        display: flex;
        align-items: center;
        justify-content: flex-start;
    }
}

.rule-checkbox-column {
    flex: 1;
}

.rule-checkbox > input[type=checkbox] {
    margin-right: 0.25em;
    + label {
        font-weight: normal;
    }
}