/* Saengsaeng Korean — classic, minimal, editorial (spec §5) */

:root {
    --color-bg: #FAF8F4;        /* Warm Ivory */
    --color-text: #292725;      /* Charcoal */
    --color-accent: #6C293A;    /* Burgundy */
    --color-accent-dark: #561f2e;
    --color-muted: #6B6764;     /* Muted Gray */
    --color-line: #DDD7D1;      /* Light Gray — dividers only, never text */
    --color-soft: #F5ECEE;      /* Pale Rose */
    --color-surface: #FFFFFF;
    --color-success: #2F6B47;
    --color-error: #A1262E;

    --font-serif: "Noto Serif KR", "Noto Serif JP", Georgia, serif;
    --font-sans: "Pretendard Variable", Pretendard, -apple-system, "Segoe UI", sans-serif;
    --font-sans-ja: "Noto Sans JP", "Pretendard Variable", sans-serif;

    --container: 72rem;
    --narrow: 44rem;
    --radius: 4px;
    --space: 1rem;
}

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

html { -webkit-text-size-adjust: 100%; }

body {
    margin: 0;
    background: var(--color-bg);
    color: var(--color-text);
    font-family: var(--font-sans);
    font-size: 1.0625rem;
    line-height: 1.75;
    word-break: keep-all;
    overflow-wrap: break-word;
}

:lang(ja) body, html[lang="ja"] body { font-family: var(--font-sans-ja); }

h1, h2, h3 {
    font-family: var(--font-serif);
    font-weight: 700;
    line-height: 1.35;
    margin: 0 0 0.6em;
    letter-spacing: -0.01em;
}
h1 { font-size: clamp(1.9rem, 4vw, 2.6rem); }
h2 { font-size: clamp(1.4rem, 2.6vw, 1.75rem); margin-top: 1.6em; }
h3 { font-size: 1.2rem; }

p { margin: 0 0 1em; }
a { color: var(--color-accent); text-underline-offset: 0.2em; }
a:hover { color: var(--color-accent-dark); }
:focus-visible { outline: 2px solid var(--color-accent); outline-offset: 2px; }

.skip-link { position: absolute; left: -999px; top: 0; background: var(--color-text); color: #fff; padding: 0.5rem 1rem; z-index: 10; }
.skip-link:focus { left: 1rem; }

.container { width: 100%; max-width: var(--container); margin: 0 auto; padding: 0 1rem; }
.narrow { max-width: var(--narrow); }
.container.narrow { max-width: calc(var(--narrow) + 2rem); }
.center { text-align: center; }
.page { padding-top: 3rem; padding-bottom: 4rem; }
.muted { color: var(--color-muted); }
.small { font-size: 0.875rem; }
.pre-wrap { white-space: pre-wrap; }
.eyebrow { color: var(--color-accent); font-size: 0.8125rem; font-weight: 600; letter-spacing: 0.12em; text-transform: uppercase; margin-bottom: 0.75rem; }
.lead { font-size: 1.1875rem; color: var(--color-muted); }
.placeholder { border: 1px dashed var(--color-line); padding: 1rem; color: var(--color-muted); }

/* ── Header ─────────────────────────────── */
.site-header { border-bottom: 1px solid var(--color-line); background: var(--color-bg); position: sticky; top: 0; z-index: 5; }
.header-inner { display: flex; align-items: center; justify-content: space-between; min-height: 4.5rem; gap: 1rem; }
.logo { display: flex; flex-direction: column; text-decoration: none; color: var(--color-text); line-height: 1.2; }
.logo-ko { font-family: var(--font-serif); font-weight: 700; font-size: 1.25rem; }
.logo-en { font-size: 0.6875rem; letter-spacing: 0.16em; text-transform: uppercase; color: var(--color-muted); }

.site-nav { display: flex; align-items: center; gap: 1.25rem; font-size: 0.9375rem; }
.site-nav a { color: var(--color-text); text-decoration: none; }
.site-nav a:hover { color: var(--color-accent); }
.site-nav .button { color: #fff; }
.nav-divider { width: 1px; height: 1.25rem; background: var(--color-line); }
.inline-form { margin: 0; display: inline; }
.link-button { background: none; border: 0; padding: 0; font: inherit; color: var(--color-text); cursor: pointer; }
.link-button:hover { color: var(--color-accent); }

.lang-switcher { display: flex; gap: 0.15rem; font-size: 0.8125rem; }
.lang-switcher a { padding: 0.15rem 0.4rem; border-radius: var(--radius); color: var(--color-muted); }
.lang-switcher a.is-current { color: var(--color-accent); font-weight: 700; background: var(--color-soft); }

.nav-toggle, .nav-toggle-label { display: none; }

@media (max-width: 860px) {
    .nav-toggle-label { display: block; width: 2.5rem; height: 2.5rem; position: relative; cursor: pointer; }
    .nav-toggle-label span, .nav-toggle-label span::before, .nav-toggle-label span::after {
        position: absolute; left: 0.5rem; right: 0.5rem; height: 2px; background: var(--color-text); content: "";
    }
    .nav-toggle-label span { top: 50%; }
    .nav-toggle-label span::before { top: -7px; left: 0; right: 0; }
    .nav-toggle-label span::after { top: 7px; left: 0; right: 0; }
    .site-nav {
        display: none; position: absolute; top: 100%; left: 0; right: 0;
        flex-direction: column; align-items: flex-start; gap: 0.9rem;
        padding: 1.25rem 1rem 1.5rem; background: var(--color-bg); border-bottom: 1px solid var(--color-line);
    }
    .nav-toggle:checked ~ .site-nav { display: flex; }
    .nav-divider { width: 100%; height: 1px; }
}

/* ── Buttons ────────────────────────────── */
.button {
    display: inline-block; padding: 0.75rem 1.4rem; border: 1px solid var(--color-accent); border-radius: var(--radius);
    background: var(--color-accent); color: #fff; font: inherit; font-weight: 600; line-height: 1.2;
    text-decoration: none; cursor: pointer;
}
.button:hover { background: var(--color-accent-dark); border-color: var(--color-accent-dark); color: #fff; }
.button-ghost { background: transparent; color: var(--color-accent); }
.button-ghost:hover { background: var(--color-soft); color: var(--color-accent-dark); }
.button-small { padding: 0.45rem 0.9rem; font-size: 0.875rem; }
.button-block { display: block; width: 100%; text-align: center; }
.actions { display: flex; flex-wrap: wrap; gap: 0.75rem; margin-top: 2rem; }

/* ── Sections ───────────────────────────── */
.hero { padding: clamp(3.5rem, 9vw, 7rem) 0; border-bottom: 1px solid var(--color-line); }
.hero h1 { font-size: clamp(2.1rem, 5vw, 3.2rem); }
.section { padding: 4rem 0; }
.section-alt { background: var(--color-soft); }
.section-header { display: flex; justify-content: space-between; align-items: baseline; gap: 1rem; margin-bottom: 1.5rem; }
.section-header h2 { margin: 0; }
.two-col { display: grid; grid-template-columns: 1fr 1.4fr; gap: 2rem 4rem; }
.two-col h2 { margin-top: 0; }
.cta-band { border-top: 1px solid var(--color-line); }
@media (max-width: 760px) { .two-col { grid-template-columns: 1fr; } }

/* ── Lessons ────────────────────────────── */
.lesson-list { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--color-line); }
.lesson-item a { display: block; padding: 1.5rem 0; border-bottom: 1px solid var(--color-line); color: inherit; text-decoration: none; }
.lesson-item a:hover h3 { color: var(--color-accent); }
.lesson-item h3 { margin: 0.25rem 0; }
.lesson-item p { margin: 0.25rem 0; }
.lesson-meta { display: flex; gap: 0.75rem; align-items: center; font-size: 0.8125rem; color: var(--color-muted); margin-bottom: 0.5rem; }
.lesson-meta a { color: var(--color-muted); }
.tag { border: 1px solid var(--color-line); border-radius: 999px; padding: 0 0.6rem; font-size: 0.75rem; }
.key-expression { font-family: var(--font-serif); color: var(--color-accent); font-size: 1.125rem; }
.key-expression-large { font-size: clamp(2rem, 5vw, 2.75rem); margin: 0.5rem 0 1rem; }
.prose ul, .prose ol { padding-left: 1.25rem; }
.prose li { margin-bottom: 0.4rem; }
.nuance { margin-top: 2.5rem; padding: 1.5rem; background: var(--color-soft); border-radius: var(--radius); }
.nuance h2 { margin-top: 0; font-size: 1.25rem; }
.notice { padding: 0.75rem 1rem; background: var(--color-soft); border-left: 3px solid var(--color-accent); border-radius: var(--radius); }
.notice-warning { border-left-color: var(--color-error); }

.filters { display: flex; flex-wrap: wrap; gap: 1rem; align-items: flex-end; margin: 2rem 0; }
.filters label { display: flex; flex-direction: column; gap: 0.25rem; font-size: 0.8125rem; color: var(--color-muted); }

/* ── Quiz ───────────────────────────────── */
.quiz { margin-top: 3rem; padding-top: 2rem; border-top: 1px solid var(--color-line); }
.quiz-question { border: 1px solid var(--color-line); border-radius: var(--radius); padding: 1.25rem; margin: 0 0 1rem; background: var(--color-surface); }
.quiz-question legend { font-weight: 600; padding: 0 0.25rem; }
.quiz-question.is-correct { border-color: var(--color-success); }
.quiz-question.is-wrong { border-color: var(--color-error); }
.quiz-number { color: var(--color-accent); }
.quiz-option { display: flex; gap: 0.6rem; align-items: center; padding: 0.4rem 0; cursor: pointer; }
.quiz-option.is-answer span { font-weight: 700; color: var(--color-success); }
.quiz-explanation { margin: 0.75rem 0 0; font-size: 0.9375rem; color: var(--color-muted); }
.quiz-score { padding: 1rem 1.25rem; margin-bottom: 1.5rem; background: var(--color-soft); border-radius: var(--radius); }
.quiz-score .score { font-family: var(--font-serif); font-size: 1.5rem; color: var(--color-accent); margin: 0; }
.quiz-score p { margin: 0.25rem 0 0; }

/* ── Classes ────────────────────────────── */
.class-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(18rem, 1fr)); gap: 1.5rem; margin: 2.5rem 0 1.5rem; }
.class-card { border: 1px solid var(--color-line); border-radius: var(--radius); padding: 1.75rem; background: var(--color-surface); }
.class-card h2 { margin-top: 0; }

/* ── Forms ──────────────────────────────── */
.form { margin-top: 2rem; }
.field { display: flex; flex-direction: column; gap: 0.35rem; margin-bottom: 1.25rem; }
.field-row { display: grid; grid-template-columns: 1fr 1fr; gap: 0 1rem; }
@media (max-width: 600px) { .field-row { grid-template-columns: 1fr; } }
label { font-weight: 600; font-size: 0.9375rem; }
input:not([type=checkbox]):not([type=radio]), select, textarea {
    width: 100%; padding: 0.7rem 0.8rem; font: inherit; font-size: 1rem; color: var(--color-text);
    background: var(--color-surface); border: 1px solid #BDB5AD; border-radius: var(--radius);
}
.filters select, .filters input { width: auto; min-width: 10rem; }
input:focus, select:focus, textarea:focus { outline: 2px solid var(--color-accent); outline-offset: 0; border-color: var(--color-accent); }
input[type=checkbox], input[type=radio] { width: 1.1rem; height: 1.1rem; accent-color: var(--color-accent); flex-shrink: 0; }
.checkbox { display: flex; gap: 0.6rem; align-items: flex-start; font-weight: 400; margin-bottom: 0.5rem; }
.checkbox input { margin-top: 0.35rem; }
.required { color: var(--color-error); }
.hint { font-size: 0.8125rem; color: var(--color-muted); font-weight: 400; }
.field-error { color: var(--color-error); font-size: 0.875rem; }
.form-errors:empty, .form-errors.validation-summary-valid { display: none; }
.form-errors { color: var(--color-error); background: #FBEFEF; border-radius: var(--radius); padding: 0.75rem 1rem; margin-bottom: 1.25rem; }
.form-errors ul { margin: 0; padding-left: 1.1rem; }
.input-validation-error { border-color: var(--color-error) !important; }
.hp { position: absolute; left: -10000px; width: 1px; height: 1px; overflow: hidden; }

.auth { max-width: 28rem; }
.social-buttons { display: grid; gap: 0.6rem; margin-top: 1.5rem; }
.divider-text { display: flex; align-items: center; gap: 1rem; color: var(--color-muted); font-size: 0.875rem; margin: 1.5rem 0 0; }
.divider-text::before, .divider-text::after { content: ""; flex: 1; height: 1px; background: var(--color-line); }

/* ── Tables & stats ─────────────────────── */
.table-wrap { overflow-x: auto; }
.table { width: 100%; border-collapse: collapse; font-size: 0.9375rem; }
.table th, .table td { text-align: left; padding: 0.7rem 0.6rem; border-bottom: 1px solid var(--color-line); vertical-align: top; }
.table th { font-weight: 600; color: var(--color-muted); font-size: 0.8125rem; }
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(10rem, 1fr)); gap: 1rem; margin: 2rem 0; }
.stats div { border: 1px solid var(--color-line); border-radius: var(--radius); padding: 1rem 1.25rem; background: var(--color-surface); }
.stats dt { font-size: 0.8125rem; color: var(--color-muted); }
.stats dd { margin: 0.25rem 0 0; font-family: var(--font-serif); font-size: 1.6rem; color: var(--color-accent); }
.stats dd a { text-decoration: none; }

/* ── Footer ─────────────────────────────── */
.site-footer { border-top: 1px solid var(--color-line); padding: 2.5rem 0; margin-top: 2rem; }
.footer-inner { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 1.5rem; align-items: flex-start; }
.footer-brand { font-family: var(--font-serif); font-weight: 700; margin: 0; }
.footer-links { display: flex; gap: 1.25rem; font-size: 0.9375rem; }
.footer-links a { color: var(--color-text); }