@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@400;500;700&display=swap');

:root {
    color-scheme: light;
    --bg: #f2f4f7;
    --bg-grad-a: #ffffff;
    --bg-grad-b: #e8edf4;
    --surface: rgba(255, 255, 255, 0.72);
    --surface-strong: rgba(255, 255, 255, 0.9);
    --text: #101827;
    --muted: #4b5563;
    --primary: #007aff;
    --secondary: #34c759;
    --danger: #dc2626;
    --border: rgba(124, 139, 160, 0.28);
    --shadow: 0 10px 28px rgba(15, 23, 42, 0.09);
    --glass-highlight: rgba(255, 255, 255, 0.4);
}

html[data-theme='dark'] {
    color-scheme: dark;
    --bg: #0a0f1a;
    --bg-grad-a: #101827;
    --bg-grad-b: #060a13;
    --surface: rgba(19, 27, 42, 0.62);
    --surface-strong: rgba(19, 27, 42, 0.86);
    --text: #eef4ff;
    --muted: #a7b4cb;
    --primary: #59a8ff;
    --secondary: #5ae4a7;
    --danger: #ff7f8f;
    --border: rgba(144, 165, 194, 0.24);
    --shadow: 0 14px 35px rgba(0, 0, 0, 0.35);
    --glass-highlight: rgba(255, 255, 255, 0.08);
}

* {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
    min-height: 100%;
}

body {
    font-family: 'Space Grotesk', sans-serif;
    color: var(--text);
    background: linear-gradient(180deg, var(--bg-grad-a) 0%, var(--bg-grad-b) 100%);
    overflow-x: hidden;
    line-height: 1.6;
}

.background-orb {
    display: none;
}

.orb-a {
    display: none;
}

.orb-b {
    display: none;
}

.background-grid {
    display: none;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    padding: 1rem clamp(1rem, 4vw, 3rem);
    background: var(--surface);
    backdrop-filter: saturate(140%) blur(18px);
    -webkit-backdrop-filter: saturate(140%) blur(18px);
    border-bottom: 1px solid var(--border);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 0.7rem;
}

.brand {
    font-weight: 700;
    letter-spacing: 0.01em;
    color: var(--text);
    text-decoration: none;
}

.nav-list {
    display: flex;
    gap: 0.75rem;
    padding: 0;
    margin: 0;
    list-style: none;
}

.nav-list a {
    display: inline-block;
    color: var(--muted);
    text-decoration: none;
    padding: 0.4rem 0.8rem;
    border-radius: 999px;
    border: 1px solid transparent;
    transition: all 200ms ease;
}

.nav-list a:hover,
.nav-list a.is-active {
    color: var(--text);
    border-color: var(--border);
    background: var(--surface-strong);
}

.theme-toggle {
    border: 1px solid var(--border);
    background: var(--surface-strong);
    color: var(--text);
    border-radius: 999px;
    padding: 0.4rem 0.8rem;
    font: inherit;
    font-size: 0.92rem;
    cursor: pointer;
}

.theme-toggle:hover {
    border-color: color-mix(in srgb, var(--border), var(--text) 24%);
}

.site-main {
    width: min(1100px, calc(100% - 2rem));
    margin: 2rem auto 4rem;
    display: grid;
    gap: 1.4rem;
}

.hero,
.panel,
.stat-card,
.project-card,
.course-block,
.category-block {
    background: var(--surface);
    border: 1px solid var(--border);
    box-shadow: var(--shadow);
    border-radius: 0.9rem;
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
}

.hero,
.panel {
    padding: clamp(1.1rem, 2.3vw, 2rem);
}

.eyebrow {
    margin: 0;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--primary);
    font-weight: 700;
    font-size: 0.72rem;
}

h1,
h2,
h3,
h4 {
    font-family: 'Space Grotesk', sans-serif;
    line-height: 1.2;
    margin-top: 0.2rem;
}

h1 {
    font-size: clamp(1.8rem, 4vw, 3rem);
    margin-bottom: 0.8rem;
}

p {
    margin: 0.45rem 0;
}

.hero-actions {
    margin-top: 1.2rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.7rem;
}

.button {
    border-radius: 999px;
    padding: 0.6rem 1.1rem;
    border: 1px solid transparent;
    text-decoration: none;
    display: inline-block;
    cursor: pointer;
    transition: box-shadow 180ms ease, border-color 180ms ease;
}

.button-primary {
    color: #ffffff;
    font-weight: 700;
    background: linear-gradient(180deg, color-mix(in srgb, var(--primary), #ffffff 10%), var(--primary));
    box-shadow: none;
}

.button-secondary {
    color: var(--text);
    border-color: var(--border);
    background: var(--surface-strong);
}

.button.small {
    padding: 0.35rem 0.8rem;
    font-size: 0.86rem;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 1rem;
}

.stat-card {
    padding: 1rem;
}

.stat-card h2 {
    margin: 0;
    color: var(--primary);
    font-size: 2rem;
}

.project-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 0.9rem;
}

.project-card {
    padding: 0;
}

.project-link {
    display: block;
    padding: 1rem;
    color: inherit;
    text-decoration: none;
}

.project-link:hover {
    background: color-mix(in srgb, var(--surface-strong), var(--glass-highlight) 32%);
}

.muted {
    color: var(--muted);
    font-size: 0.92rem;
}

.course-block {
    padding: 1rem;
    margin-bottom: 0.9rem;
}

.category-block {
    margin-top: 0.75rem;
    padding: 0.9rem;
    background: var(--surface-strong);
}

.exercise-list {
    margin: 0;
    padding: 0;
    list-style: none;
    display: grid;
    gap: 0.7rem;
}

.exercise-list li {
    background: var(--surface);
    border-radius: 0.8rem;
    border: 1px solid var(--border);
    padding: 0.8rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 0.8rem;
    flex-wrap: wrap;
}

.exercise-meta {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--muted);
    font-size: 0.86rem;
    flex-wrap: wrap;
}

.source-viewer {
    margin: 0.7rem 0 0;
    overflow: auto;
    max-height: 65vh;
    background: var(--surface-strong);
    border: 1px solid var(--border);
    border-radius: 0.9rem;
    padding: 0.9rem;
}

.source-viewer code {
    display: block;
    font-family: 'Cascadia Code', 'Consolas', monospace;
    font-size: 0.9rem;
    color: var(--text);
    white-space: pre;
}

.error-message {
    color: var(--danger);
    font-weight: 700;
}

.site-footer {
    width: min(1100px, calc(100% - 2rem));
    margin: 0 auto 1.2rem;
    padding: 1rem;
    border-top: 1px solid var(--border);
    color: var(--muted);
}

.reveal {
    opacity: 1;
    transform: none;
    transition: none;
}

.reveal.is-visible {
    opacity: 1;
    transform: none;
}

@media (max-width: 700px) {
    .site-main {
        width: min(1100px, calc(100% - 1rem));
    }

    .site-header {
        padding: 0.8rem 0.8rem;
    }

    .header-actions {
        gap: 0.5rem;
    }

    .theme-toggle {
        padding: 0.35rem 0.62rem;
        font-size: 0.86rem;
    }

    .exercise-list li {
        align-items: flex-start;
    }
}