:root {
    --theme: #fff;
    --content: #1f2937;
    --vintage-meta: #5b808d;
    --border: #eee;
    --code-bg: #f0f0f0;
    --code-block-bg: #f8f8f8;
    --radius: 3px;

    --vintage-link: #285e8e;
    --vintage-link-soft: #428bca;
    --vintage-link-border: #285e8e;
    --vintage-heading-accent: brown;
    --vintage-rule: #333;
    --vintage-quote-border: #666;
    --vintage-code-border: #e7eaed;
    --vintage-shadow: none;

    --success: #237a35;
    --danger: #a6483a;

    --body-font: "Charter", "Bitstream Charter", "Sitka Text", Cambria, "Times New Roman", "Songti SC", "SimSong", "思源宋体 CN", "黑体", "宋体", serif;
    --heading-font: "Charter", "Bitstream Charter", "Sitka Text", Cambria, "Times New Roman", "黑体", "宋体", serif;
    --code-font: monospace, "Consolas", "SimSong", "思源宋体 CN";

    color-scheme: light;
}

@media (prefers-color-scheme: dark) {
    :root {
        --theme: #171716;
        --content: #e8dfd0;
        --vintage-meta: #9eb6bb;
        --border: #3a3731;
        --code-bg: #282722;
        --code-block-bg: #232321;

        --vintage-link: #9fc8e6;
        --vintage-link-soft: #c3ddf0;
        --vintage-link-border: #6f9cbc;
        --vintage-heading-accent: #d29a7f;
        --vintage-rule: #6f685d;
        --vintage-quote-border: #8d8475;
        --vintage-code-border: #403d37;
        --vintage-shadow: 0 14px 34px rgba(0, 0, 0, 0.22);

        --success: #6fa678;
        --danger: #c17b6a;

        color-scheme: dark;
    }
}

/* Self-hosted Charter webfont, same as the main site (assets/css/extended/custom.css). */
@font-face {
    font-family: "Charter";
    font-style: normal;
    font-weight: normal;
    font-display: swap;
    src: local("Charter"), url("/fonts/xcharter/XCharter-Roman.woff2") format("woff2");
}

@font-face {
    font-family: "Charter";
    font-style: normal;
    font-weight: bold;
    font-display: swap;
    src: local("Charter"), url("/fonts/xcharter/XCharter-Bold.woff2") format("woff2");
}

@font-face {
    font-family: "Charter";
    font-style: italic;
    font-weight: normal;
    font-display: swap;
    src: local("Charter"), url("/fonts/xcharter/XCharter-Italic.woff2") format("woff2");
}

@font-face {
    font-family: "Charter";
    font-style: italic;
    font-weight: bold;
    font-display: swap;
    src: local("Charter"), url("/fonts/xcharter/XCharter-BoldItalic.woff2") format("woff2");
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: var(--body-font);
    font-weight: normal;
    color: var(--content);
    background: var(--theme);
}

.app-header {
    position: sticky;
    top: 0;
    z-index: 10;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    padding: 18px clamp(18px, 4vw, 48px);
    background: var(--theme);
    border-bottom: 1px solid var(--border);
}

.eyebrow {
    margin: 0 0 4px;
    color: var(--vintage-meta);
    font-size: 12px;
    font-weight: 700;
    text-transform: uppercase;
}

h1,
h2 {
    margin: 0;
    font-family: var(--heading-font);
    font-weight: normal;
}

h1 {
    color: var(--content);
    font-size: 24px;
    line-height: 1.25;
}

h2 {
    color: var(--vintage-link);
    font-size: 20px;
    margin-bottom: 16px;
}

.menu {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.menu a,
.button-link,
button {
    min-height: 40px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0 14px;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    background: var(--theme);
    color: var(--content);
    text-decoration: none;
    font: inherit;
    font-family: var(--body-font);
    font-weight: normal;
    cursor: pointer;
}

.menu a:hover,
.button-link:hover,
button:hover {
    border-color: var(--vintage-link-border);
}

main {
    width: min(1180px, calc(100% - 32px));
    margin: 24px auto 48px;
    display: grid;
    gap: 20px;
}

.panel {
    background: var(--theme);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--vintage-shadow);
    padding: clamp(16px, 3vw, 24px);
}

.controls {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 14px;
}

label {
    display: grid;
    gap: 7px;
    color: var(--vintage-meta);
    font-size: 13px;
    font-weight: 700;
}

select,
input,
textarea {
    width: 100%;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 10px 11px;
    color: var(--content);
    background: var(--theme);
    font: inherit;
    font-family: var(--body-font);
}

select:focus,
input:focus,
textarea:focus {
    outline: 2px solid color-mix(in srgb, var(--vintage-link) 24%, transparent);
    border-color: var(--vintage-link-border);
}

.json-input {
    margin-top: 16px;
}

textarea {
    min-height: 260px;
    resize: vertical;
    font-family: var(--code-font);
    font-size: 13px;
    line-height: 1.45;
}

.actions {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 16px;
}

button,
.button-link {
    background: var(--vintage-link);
    border-color: var(--vintage-link-border);
    color: #fff;
}

button:hover,
.button-link:hover {
    background: var(--vintage-link-soft);
    border-color: var(--vintage-link-soft);
    color: #fff;
}

button.secondary {
    background: var(--theme);
    color: var(--content);
    border-color: var(--border);
}

button.secondary:hover {
    background: var(--theme);
    color: var(--vintage-link);
    border-color: var(--vintage-link-border);
}

.button-link.disabled {
    pointer-events: none;
    opacity: 0.45;
}

.status {
    min-height: 22px;
    margin: 12px 0 0;
    color: var(--vintage-meta);
    font-weight: 650;
}

.status.error {
    color: var(--danger);
}

.status.success {
    color: var(--success);
}

.readme-content {
    max-width: 880px;
    line-height: 1.6;
    font-family: var(--body-font);
}

.readme-content h1 {
    color: var(--content);
    border-bottom: 1px solid var(--border);
    padding-bottom: 8px;
    margin-bottom: 14px;
}

.readme-content h2 {
    color: var(--vintage-link);
    margin-top: 24px;
}

.readme-content code,
.readme-content pre {
    font-family: var(--code-font);
    background: var(--code-bg);
    border-radius: var(--radius);
}

.readme-content code {
    padding: 2px 4px;
}

.readme-content pre {
    background: var(--code-block-bg);
    border: 1px solid var(--vintage-code-border);
    overflow-x: auto;
    padding: 14px;
}

.preview-panel {
    min-height: 560px;
}

#preview-frame {
    width: 100%;
    min-height: 680px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--theme);
}

@media (max-width: 820px) {
    .app-header {
        position: static;
        align-items: flex-start;
        flex-direction: column;
    }

    .controls {
        grid-template-columns: 1fr;
    }
}