/* ---------- CSS VARIABLES (LIGHT DEFAULT) ---------- */
:root {
    --bg-gradient-start: #eef2f7;
    --bg-gradient-end: #d9e0e8;
    --card-bg: #ffffff;
    --text-primary: #1a2a3f;
    --text-secondary: #2c3f4f;
    --text-muted: #4a6a7f;
    --heading-gradient-start: #1f3b4c;
    --heading-gradient-end: #2c5a6e;
    --border-light: #e2e8f0;
    --code-bg: #f0f4f9;
    --code-border: #e2e9f0;
    --code-color: #c44536;
    --link-color: #2c7da0;
    --link-hover: #1f5e7a;
    --blockquote-bg: #f8fafc;
    --blockquote-border: #2c7da0;
    --hr-gradient-start: #cbdde6;
    --hr-gradient-end: #e9f0f5;
    --list-marker: #2c7da0;
    --shadow: 0 20px 35px -12px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.03);
    --btn-bg: #2c7da0;
    --btn-hover: #236b8a;
    --btn-text: white;
    --footer-border: #dce5ec;
}

/* ---------- DARK THEME (system preference) ---------- */
@media (prefers-color-scheme: dark) {
    :root {
        --bg-gradient-start: #121826;
        --bg-gradient-end: #0f141f;
        --card-bg: #1e2432;
        --text-primary: #eef2ff;
        --text-secondary: #cbd5e6;
        --text-muted: #94a3b8;
        --heading-gradient-start: #7ab3c8;
        --heading-gradient-end: #a0c6d9;
        --border-light: #2d3a4b;
        --code-bg: #0f131e;
        --code-border: #2a3548;
        --code-color: #f28b82;
        --link-color: #6ab0de;
        --link-hover: #8cc9f0;
        --blockquote-bg: #1a212f;
        --blockquote-border: #5d9bc3;
        --hr-gradient-start: #2d3e52;
        --hr-gradient-end: #1f2a38;
        --list-marker: #6ab0de;
        --shadow: 0 20px 35px -12px rgba(0, 0, 0, 0.4), 0 1px 2px rgba(0, 0, 0, 0.2);
        --btn-bg: #5d9bc3;
        --btn-hover: #7eb2d1;
        --btn-text: #0f141f;
        --footer-border: #2d3e4c;
    }
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background: linear-gradient(145deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
    font-family: system-ui, 'Segoe UI', 'Roboto', 'Helvetica Neue', 'Noto Sans', sans-serif;
    line-height: 1.5;
    color: var(--text-primary);
    padding: 2rem 1rem;
    transition: background 0.2s ease, color 0.2s ease;
}

/* main card container */
.document-container {
    max-width: 1100px;
    margin: 0 auto;
    background: var(--card-bg);
    border-radius: 32px;
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: background 0.2s ease, box-shadow 0.2s ease;
}

/* inner content padding */
.content {
    padding: 2.5rem 2rem;
}

@media (max-width: 640px) {
    body {
        padding: 1rem;
    }
    .content {
        padding: 1.8rem 1.25rem;
    }
}

/* typography */
h1 {
    font-size: 2.4rem;
    font-weight: 700;
    letter-spacing: -0.01em;
    background: linear-gradient(135deg, var(--heading-gradient-start), var(--heading-gradient-end));
    background-clip: text;
    -webkit-background-clip: text;
    color: transparent;
    margin-bottom: 0.5rem;
    border-left: 5px solid var(--link-color);
    padding-left: 1.2rem;
}

h2 {
    font-size: 1.75rem;
    font-weight: 600;
    margin: 1.8rem 0 0.8rem 0;
    padding-bottom: 0.4rem;
    border-bottom: 2px solid var(--border-light);
    color: var(--heading-gradient-start);
}

h3 {
    font-size: 1.35rem;
    font-weight: 600;
    margin: 1.5rem 0 0.6rem 0;
    color: var(--link-color);
}

p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

/* copyright line under h1 */
.content > p:first-of-type {
    font-size: 0.95rem;
    color: var(--text-muted);
    margin-top: -0.2rem;
    margin-bottom: 1.8rem;
    font-weight: 450;
    border-left: 3px solid var(--border-light);
    padding-left: 1.2rem;
}

strong {
    color: var(--heading-gradient-end);
    font-weight: 600;
}

/* lists */
ul, ol {
    margin: 0.8rem 0 1rem 1.8rem;
}

li {
    margin: 0.45rem 0;
    color: var(--text-secondary);
}

li::marker {
    color: var(--list-marker);
}

ul ul, ol ul, ul ol {
    margin-top: 0.3rem;
    margin-bottom: 0.3rem;
}

/* code & inline code blocks */
code {
    font-family: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', 'SF Mono', monospace;
    background: var(--code-bg);
    padding: 0.2rem 0.4rem;
    border-radius: 8px;
    font-size: 0.85em;
    color: var(--code-color);
    font-weight: 500;
    border: 1px solid var(--code-border);
    white-space: nowrap;
}

a code {
    color: var(--link-color);
    background: color-mix(in srgb, var(--link-color) 10%, var(--code-bg));
    border-color: color-mix(in srgb, var(--link-color) 30%, var(--code-border));
}

/* links */
a {
    color: var(--link-color);
    text-decoration: none;
    font-weight: 500;
    transition: all 0.2s;
    border-bottom: 1px solid transparent;
}

a:hover {
    color: var(--link-hover);
    border-bottom-color: var(--link-color);
}

/* download button styling */
.download-container {
    margin: 1.5rem 0 2rem 0;
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    align-items: center;
    justify-content: flex-start;
}
.btn-download {
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    background: var(--btn-bg);
    color: var(--btn-text);
    padding: 0.75rem 1.5rem;
    border-radius: 60px;
    font-weight: 600;
    font-size: 1rem;
    border: none;
    transition: all 0.2s ease;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    text-decoration: none;
    border-bottom: 0;
}
.btn-download:hover {
    background: var(--btn-hover);
    color: var(--btn-text);
    transform: translateY(-2px);
    box-shadow: 0 8px 18px rgba(0,0,0,0.15);
    border-bottom: 0;
}
.btn-download:active {
    transform: translateY(1px);
}
.download-note {
    font-size: 0.85rem;
    color: var(--text-muted);
    background: var(--code-bg);
    padding: 0.3rem 0.8rem;
    border-radius: 40px;
    border: 1px solid var(--border-light);
}

/* GitHub footer link */
.github-footer {
    margin-top: 2.8rem;
    padding-top: 1.8rem;
    border-top: 2px solid var(--footer-border);
    text-align: center;
    font-size: 1rem;
}
.github-footer a {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 600;
    background: var(--code-bg);
    padding: 0.55rem 1.3rem;
    border-radius: 40px;
    border: 1px solid var(--border-light);
    transition: all 0.2s;
    text-decoration: none;
}
.github-footer a:hover {
    background: var(--link-color);
    color: var(--btn-text);
    border-color: var(--link-color);
    transform: translateY(-2px);
}
.github-footer a:hover .gh-icon {
    filter: brightness(0) invert(1);
}
.gh-icon {
    font-size: 1.2rem;
    font-weight: normal;
    transition: filter 0.2s;
}

/* blockquotes */
blockquote {
    margin: 1rem 0;
    padding: 0.6rem 1.2rem;
    background: var(--blockquote-bg);
    border-left: 4px solid var(--blockquote-border);
    border-radius: 12px;
    color: var(--text-secondary);
}

/* horizontal rule */
hr {
    margin: 2rem 0;
    border: none;
    height: 1px;
    background: linear-gradient(90deg, var(--hr-gradient-start), var(--hr-gradient-end), var(--hr-gradient-start));
}

/* path highlights */
.path-highlight {
    background: var(--code-bg);
    padding: 0.2rem 0.4rem;
    border-radius: 8px;
    font-family: monospace;
    font-size: 0.85em;
}

/* table styling */
table {
    width: 100%;
    border-collapse: collapse;
    margin: 1rem 0;
}

th, td {
    border: 1px solid var(--border-light);
    padding: 0.6rem;
    text-align: left;
    color: var(--text-secondary);
}

th {
    background: var(--code-bg);
    font-weight: 600;
}

img {
    max-width: 100%;
    height: auto;
}

/* Logo styling */
.logo {
    display: block;
    margin: 0.5rem 0 1rem 0;
    border-radius: 16px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    object-fit: contain;
}

.footer-logo {
    display: inline-block;
    margin-right: 0.8rem;
    vertical-align: middle;
    border-radius: 6px;
    object-fit: contain;
}

/* Adaptive logo for dark theme */
@media (prefers-color-scheme: dark) {
    .logo, .footer-logo {
        filter: brightness(0.95);
    }
}

/* ---------- PRINT MEDIA OVERRIDES (clean, black on white) ---------- */
@media print {
    body {
        background: white;
        padding: 0;
        margin: 0;
        color: black;
    }
    .document-container {
        box-shadow: none;
        border-radius: 0;
        background: white;
        max-width: 100%;
    }
    .content {
        padding: 1.2rem;
    }
    h1, h2, h3, h4 {
        color: black;
        background: none;
        -webkit-background-clip: unset;
        border-left-color: #333;
        border-bottom-color: #ccc;
    }
    h1 {
        color: black;
        background: none;
    }
    a {
        color: black;
        text-decoration: underline;
        border-bottom: none;
    }
    a::after {
        content: " (" attr(href) ")";
        font-size: 0.85em;
        font-weight: normal;
        text-decoration: none;
    }
    .btn-download {
        background: #eee;
        color: black;
        border: 1px solid #aaa;
        box-shadow: none;
        padding: 0.5rem 1rem;
    }
    .btn-download::after {
        content: " (" attr(href) ")";
        font-size: 0.8em;
        font-weight: normal;
    }
    .github-footer a {
        background: #f4f4f4;
        border: 1px solid #aaa;
        color: black;
    }
    .github-footer a::after {
        content: " (" attr(href) ")";
    }
    code {
        background: #f4f4f4;
        border: 1px solid #aaa;
        color: #b33;
        white-space: pre-wrap;
        word-break: break-all;
    }
    pre, code {
        page-break-inside: avoid;
    }
    p, li, blockquote {
        color: black;
    }
    ul li::marker, ol li::marker {
        color: black;
    }
    .content > p:first-of-type {
        border-left-color: #aaa;
        color: #333;
    }
    hr {
        background: #ccc;
    }
    .document-container, body {
        background: white;
    }
    h2, h3 {
        page-break-after: avoid;
        page-break-inside: avoid;
    }
    blockquote {
        border-left-color: #666;
        background: #fafafa;
    }
}