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

html {
    min-width: 320px;
    color: var(--color-text-primary);
    background:
        radial-gradient(circle at 12% 0, var(--color-paper-grain), transparent 28rem),
        var(--color-bg-page);
    font-family: var(--font-family-ui);
    font-size: 16px;
    letter-spacing: 0;
    scroll-behavior: smooth;
}

#course-path {
    scroll-margin-top: var(--space-xl);
}

body {
    min-width: 320px;
    margin: 0;
    color: var(--color-text-primary);
    background: transparent;
    font-size: var(--font-size-body-md);
    line-height: var(--line-height-body);
    text-rendering: optimizeLegibility;
}

img,
iframe {
    max-width: 100%;
}

img {
    display: block;
}

button,
input,
select,
textarea {
    font: inherit;
}

a {
    color: var(--color-link-default);
    text-decoration-color: color-mix(in srgb, currentColor 42%, transparent);
    text-decoration-thickness: 1px;
    text-underline-offset: 0.18em;
    transition:
        color var(--transition-soft),
        text-decoration-color var(--transition-soft);
}

a:hover {
    color: var(--color-accent-primary-hover);
    text-decoration-color: currentColor;
}

a:focus-visible,
button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
    outline: 3px solid var(--color-focus-ring);
    outline-offset: 3px;
}

h1,
h2,
h3,
h4,
h5,
h6 {
    margin-block: 0;
    color: var(--color-text-primary);
    font-family: var(--font-family-display);
    font-weight: var(--font-weight-bold);
    letter-spacing: var(--letter-spacing-tight);
    line-height: var(--line-height-heading);
}

p,
ul,
ol,
dl {
    margin-block: 0;
}

p,
li,
dd {
    line-height: var(--line-height-body);
}

strong {
    font-weight: var(--font-weight-semibold);
}

.skip-link {
    position: absolute;
    top: var(--space-sm);
    left: var(--space-sm);
    z-index: 10;
    padding: var(--space-xs) var(--space-sm);
    color: var(--color-button-primary-text);
    background: var(--color-button-primary-bg);
    border-radius: var(--radius-sm);
    transform: translateY(-160%);
}

.skip-link:focus {
    transform: translateY(0);
}

.site-header {
    background: color-mix(in srgb, var(--color-surface-primary) 90%, transparent);
    border-bottom: var(--border-default);
}

.site-nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: min(var(--site-max-width), calc(100% - (var(--site-gutter) * 2)));
    margin: 0 auto;
    padding: var(--space-md) 0;
    gap: var(--space-lg);
}

.site-nav__brand {
    color: var(--color-text-primary);
    font-family: var(--font-family-display);
    font-size: 1.25rem;
    font-weight: var(--font-weight-bold);
    letter-spacing: -0.015em;
    text-decoration: none;
    white-space: nowrap;
}

.site-nav__links {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-md) var(--space-lg);
    align-items: center;
}

.site-nav__links a {
    color: var(--color-text-secondary);
    font-size: var(--font-size-body-sm);
    font-weight: var(--font-weight-medium);
    text-decoration: none;
}

.site-nav__links a:hover {
    color: var(--color-text-primary);
}

.nav-form {
    margin: 0;
}

.nav-button {
    padding: 0;
    color: var(--color-text-muted);
    font: inherit;
    font-size: var(--font-size-body-sm);
    font-weight: var(--font-weight-medium);
    background: transparent;
    border: 0;
    cursor: pointer;
    text-decoration: underline;
    text-decoration-color: color-mix(in srgb, currentColor 35%, transparent);
    text-decoration-thickness: 1px;
    text-underline-offset: 0.18em;
    transition: color var(--transition-soft);
}

.nav-button:hover {
    color: var(--color-text-primary);
}

.site-main {
    min-height: 70vh;
}

.site-footer {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: var(--space-md) var(--space-xl);
    width: min(var(--site-max-width), calc(100% - (var(--site-gutter) * 2)));
    margin: 0 auto;
    padding: var(--space-xl) 0 var(--space-2xl);
    color: var(--color-text-muted);
    border-top: var(--border-default);
}

.site-footer p {
    max-width: none;
}

@media (max-width: 760px) {
    .site-nav {
        display: grid;
        align-items: start;
    }

    .site-nav__links {
        gap: var(--space-sm) var(--space-md);
    }
}