/* AI Knowledge Hub — Dark Theme (default), Light Theme via [data-theme="light"] */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* ===== Theme Variables ===== */
:root {
    --bg: #0f1117;
    --card-bg: #1a1d27;
    --card-hover: #22263a;
    --text: #e4e4e7;
    --text-dim: #8b8fa3;
    --text-soft: #5c5f6e;
    --accent: #7c8aff;
    --accent-dim: #5a67d8;
    --border: #2a2d3a;
    --green: #4ade80;
    --orange: #f59e0b;
    --red: #f87171;
    --number-color: #fff;
}

[data-theme="light"] {
    --bg: #f8f9fa;
    --card-bg: #ffffff;
    --card-hover: #f1f3f5;
    --text: #1a1d2e;
    --text-dim: #555a6b;
    --text-soft: #a0a5b5;
    --accent: #4f5fd9;
    --accent-dim: #3d4bc0;
    --border: #e2e5ea;
    --number-color: #1a1d2e;
    --green: #16a34a;
    --orange: #d97706;
    --red: #dc2626;
}

html { font-size: 16px; }
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", "PingFang SC", "Microsoft YaHei", sans-serif;
    background: var(--bg);
    color: var(--text);
    display: flex;
    flex-direction: column;
    -webkit-tap-highlight-color: transparent;
    transition: background 0.3s, color 0.3s;
}

/* ===== Theme Toggle ===== */
.theme-toggle {
    position: fixed;
    top: 18px;
    right: 20px;
    z-index: 100;
    background: var(--card-bg);
    border: 1px solid var(--border);
    color: var(--text-dim);
    width: 38px;
    height: 38px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.2s, color 0.2s;
}
.theme-toggle:hover { background: var(--card-hover); color: var(--accent); }

/* ===== Mobile Base (default) ===== */
header {
    text-align: center;
    padding: 48px 20px 36px;
}
.tagline { margin-top: 6px; color: var(--text-dim); font-size: 0.85rem; line-height: 1.5; }

/* ===== Hero (Homepage) ===== */
.hero {
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    padding: 8px 20px 4px;
}
.hero-title {
    font-size: 2rem;
    font-weight: 800;
    line-height: 1.05;
    letter-spacing: 0.04em;
    color: var(--text);
    margin: 0 0 8px;
}
.hero-brand {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-dim);
    letter-spacing: 0.06em;
    margin: 0 0 16px;
}
.hero-sub {
    font-size: 0.9rem;
    color: var(--accent);
    font-weight: 500;
    line-height: 1.4;
    margin: 0 0 10px;
    max-width: 480px;
}
.hero-body {
    font-size: 0.82rem;
    color: var(--text-dim);
    line-height: 1.45;
    margin: 0 0 6px;
    max-width: 500px;
}
.hero-body--tight { margin-top: 0; }
.hero-body strong { color: var(--text); font-weight: 600; }
.hero-body--lead {
    font-size: 0.92rem;
    color: var(--text);
    font-weight: 600;
    margin-bottom: 16px;
}
.hero-questions {
    list-style: none;
    margin: 0 0 20px;
    padding: 0;
    max-width: 520px;
}
.hero-questions li {
    font-size: 0.85rem;
    color: var(--text);
    line-height: 1.6;
    padding: 2px 0;
}
.hero-questions li span {
    color: var(--text-dim);
    font-size: 0.78rem;
}

/* Hero navigation links */
.hero-nav {
    display: flex;
    flex-direction: column;
    gap: 6px;
}
.hero-link {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
    padding: 10px 14px;
    border-radius: 10px;
    transition: background 0.2s, border-color 0.2s;
    min-height: 44px;
    background: var(--card-bg);
    border: 1px solid var(--border);
}
.hero-link:active { background: var(--card-hover); }
.hero-link-icon { font-size: 1.3rem; flex-shrink: 0; }
.hero-link-text { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 2px; }
.hero-link-text strong { font-size: 0.9rem; color: var(--text); font-weight: 600; }
.hero-link-text small { font-size: 0.72rem; color: var(--text-dim); line-height: 1.25; }
.hero-link-badge {
    font-size: 0.68rem;
    padding: 3px 8px;
    border-radius: 5px;
    background: rgba(245, 158, 11, 0.12);
    color: var(--orange);
    white-space: nowrap;
    flex-shrink: 0;
}

/* Feature Cards — subtle secondary actions, below main nav */
.feature-cards {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-top: 6px;
}
.feature-card {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 14px;
    border-radius: 8px;
    cursor: pointer;
    transition: background 0.2s, border-color 0.2s;
    background: var(--card-bg);
    border: 1px solid var(--border);
    min-height: 44px;
    -webkit-tap-highlight-color: transparent;
}
.feature-card:hover { border-color: var(--accent); }
.feature-card:active { background: var(--card-hover); }
.feature-card-icon { font-size: 1.1rem; flex-shrink: 0; opacity: 0.8; }
.feature-card-text { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 1px; }
.feature-card-text strong { font-size: 0.8rem; color: var(--text-dim); font-weight: 500; }
.feature-card-text small { font-size: 0.68rem; color: var(--text-soft); line-height: 1.2; }

/* Toast notification */
.toast {
    position: fixed;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%) translateY(16px);
    background: var(--card-bg);
    border: 1px solid var(--border);
    color: var(--text);
    padding: 12px 24px;
    border-radius: 10px;
    font-size: 0.85rem;
    z-index: 1000;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s, transform 0.3s;
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.35);
    white-space: nowrap;
}
.toast--visible {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
    pointer-events: auto;
}

/* Home bottom cards (开发者 / 初衷+反馈) */
.home-bottom-cards {
    max-width: 500px;
    margin: 0 auto;
    padding: 0 20px 4px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 8px;
}
.home-bottom-card {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 12px;
    border-radius: 10px;
    background: var(--card-bg);
    border: 1px solid var(--border);
    text-decoration: none;
    transition: border-color 0.15s, background 0.15s;
    min-width: 0;
}
.home-bottom-card--full {
    grid-column: 1 / -1;
    justify-content: center;
}
.home-bottom-card--full .home-bottom-text {
    flex: 0 0 auto;
}
.home-bottom-card:hover { border-color: var(--accent); }
.home-bottom-card:active { background: var(--card-hover); }
.home-bottom-icon { font-size: 1.2rem; flex-shrink: 0; }
.home-bottom-text { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 2px; }
.home-bottom-text strong { font-size: 0.85rem; color: var(--text); font-weight: 600; }
.home-bottom-text small { font-size: 0.7rem; color: var(--text-dim); line-height: 1.3; }

/* Footer */
footer {
    text-align: center;
    padding: 6px 20px 12px;
    color: var(--text-soft);
    font-size: 0.7rem;
    line-height: 1.5;
}
footer a { color: var(--accent); text-decoration: none; }
.footer-name {
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--text-dim);
    margin-bottom: 4px;
}
.footer-desc {
    font-size: 0.7rem;
    color: var(--text-soft);
    margin-bottom: 6px;
    line-height: 1.4;
}
.footer-legal {
    font-size: 0.65rem;
    color: var(--text-soft);
    opacity: 0.7;
    line-height: 1.4;
}

/* ===== Shared: Page Header ===== */
.page-header {
    text-align: center;
    padding: 40px 20px 28px;
}
.page-header h1 { font-size: 1.4rem; font-weight: 700; color: var(--text); }
.back-link {
    display: inline-block;
    margin-bottom: 16px;
    color: var(--accent);
    text-decoration: none;
    font-size: 0.85rem;
}
.back-link:hover { text-decoration: underline; }
.article-meta {
    margin: 8px 0 4px;
    display: flex;
    gap: 10px;
    justify-content: center;
    align-items: center;
    font-size: 0.78rem;
    color: var(--text-dim);
}
.article-category {
    background: rgba(124, 138, 255, 0.12);
    color: var(--accent);
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.72rem;
}
.article-date { color: var(--text-dim); }
.article-locked { font-size: 0.85rem; }

/* ===== Tag Filter Bar ===== */
.tag-filter {
    max-width: 780px;
    margin: 0 auto 4px;
    padding: 0 20px 16px;
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}
.tag-chip {
    display: inline-block;
    padding: 4px 12px;
    border-radius: 6px;
    font-size: 0.75rem;
    text-decoration: none;
    color: var(--text-dim);
    background: var(--card-bg);
    border: 1px solid var(--border);
    transition: background 0.15s, border-color 0.15s, color 0.15s;
    white-space: nowrap;
}
.tag-chip:hover { border-color: var(--accent); color: var(--accent); }
.tag-chip--active {
    background: rgba(124, 138, 255, 0.15);
    border-color: var(--accent);
    color: var(--accent);
    font-weight: 600;
}

/* Post card tags */
.post-card-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 4px;
    margin-top: 6px;
}
.post-card-tag {
    font-size: 0.65rem;
    padding: 1px 7px;
    border-radius: 4px;
    background: rgba(124, 138, 255, 0.08);
    color: var(--accent-dim);
    white-space: nowrap;
}

/* ===== Article Grid (image + title cards) ===== */
.article-grid {
    max-width: 780px;
    margin: 0 auto;
    padding: 0 20px 40px;
    display: grid;
    grid-template-columns: 1fr;
    gap: 14px;
    flex: 1;
}
.post-card {
    display: flex;
    align-items: center;
    gap: 16px;
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 16px 20px;
    text-decoration: none;
    color: var(--text);
    transition: background 0.15s, border-color 0.15s;
    min-height: 44px;
}
.post-card:active { background: var(--card-hover); }
.post-card:hover { border-color: var(--accent); }

.post-card-img {
    flex-shrink: 0;
    width: 52px;
    height: 52px;
    border-radius: 8px;
    background: var(--accent);
    display: flex;
    align-items: center;
    justify-content: center;
}
.post-card-placeholder {
    font-size: 1.3rem;
    font-weight: 700;
    color: #fff;
}
.post-card-body { flex: 1; min-width: 0; }
.post-card-cat {
    font-size: 0.7rem;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}
.post-card-body h2 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-top: 3px;
    line-height: 1.35;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}
.post-card-takeaway {
    font-size: 0.8rem;
    color: var(--text-dim);
    margin-top: 6px;
    line-height: 1.45;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

/* ===== Article Content ===== */
.article-content {
    max-width: 680px;
    margin: 0 auto;
    padding: 0 20px 48px;
    flex: 1;
    line-height: 1.75;
    font-size: 0.95rem;
}
.article-content h2 { font-size: 1.2rem; color: var(--text); margin: 28px 0 10px; }
.article-content h3 { font-size: 1.05rem; color: var(--text); margin: 22px 0 8px; }
.article-content p { margin: 10px 0; }
.article-content ul, .article-content ol { margin: 8px 0; padding-left: 22px; }
.article-content li { margin: 4px 0; }
.article-content strong { color: var(--text); }
.article-content code {
    background: rgba(124, 138, 255, 0.12);
    color: var(--accent);
    padding: 1px 6px;
    border-radius: 4px;
    font-size: 0.88em;
}
.article-content blockquote {
    border-left: 3px solid var(--accent);
    margin: 12px 0;
    padding: 8px 16px;
    color: var(--text-dim);
}

/* ===== Invite Form ===== */
.invite-form-wrapper {
    flex: 1;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    padding: 32px 20px;
}
.invite-form {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 32px 28px;
    width: 100%;
    max-width: 380px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}
.invite-form label { font-size: 0.9rem; color: var(--text-dim); }
.invite-form input {
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 12px 14px;
    color: var(--text);
    font-size: 1rem;
    outline: none;
    transition: border 0.15s;
}
.invite-form input:focus { border-color: var(--accent); }
.invite-form button {
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 8px;
    padding: 12px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    min-height: 44px;
    transition: background 0.15s;
}
.invite-form button:hover { background: var(--accent-dim); }
.error-msg { color: var(--red); font-size: 0.85rem; text-align: center; margin-top: 4px; }
.empty-state { padding: 48px 20px; text-align: center; color: var(--text-dim); flex: 1; }

/* ===== CV Page — Single Column ===== */
.cv-header { position: relative; }
.cv-avatar {
    width: 96px;
    height: 96px;
    border-radius: 50%;
    object-fit: cover;
    border: 2px solid var(--border);
    margin-bottom: 16px;
    box-shadow: 0 0 0 4px var(--card-bg), 0 0 0 6px var(--accent);
}
.back-link-fixed {
    position: fixed;
    top: 18px;
    left: 20px;
    z-index: 100;
    margin-bottom: 0;
}
.cv-name-en { font-weight: 400; color: var(--text-dim); font-size: 0.85em; }
.cv-lang-toggle {
    display: inline-block;
    margin-top: 10px;
    background: var(--card-bg);
    border: 1px solid var(--border);
    color: var(--accent);
    padding: 4px 14px;
    border-radius: 5px;
    font-size: 0.75rem;
    font-weight: 600;
    cursor: pointer;
    font-family: inherit;
    letter-spacing: 0.03em;
    transition: all 0.15s;
}
.cv-lang-toggle:hover { background: var(--card-hover); border-color: var(--accent); }

/* Single column layout */
.cv-main {
    max-width: 700px;
    margin: 0 auto;
    padding: 0 20px 48px;
    width: 100%;
}
.cv-contact { font-size: 0.8rem; color: var(--text-dim); line-height: 1.6; }

/* Sections */
.cv-section { margin-bottom: 30px; }
.cv-section h2 {
    font-size: 0.7rem;
    font-weight: 700;
    color: var(--text-soft);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: 12px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--border);
}

/* Summary block */
.cv-summary {
    border-left: 2px solid var(--accent);
    padding: 4px 0 4px 16px;
    margin-bottom: 32px;
}
.cv-summary h2 { border-bottom: none; padding-bottom: 0; margin-bottom: 8px; }
.cv-summary p {
    font-size: 0.86rem;
    color: var(--text);
    line-height: 1.75;
}

/* Items */
.cv-item { margin-bottom: 20px; }
.cv-item:last-child { margin-bottom: 0; }
.cv-item-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    flex-wrap: wrap;
    gap: 8px;
}
.cv-item-header strong { font-size: 0.88rem; color: var(--text); font-weight: 600; }
.cv-item-header span { font-size: 0.72rem; color: var(--text-soft); white-space: nowrap; }
.cv-item-sub {
    font-size: 0.76rem;
    color: var(--accent);
    margin: 2px 0 6px;
    font-weight: 500;
}
.cv-item ul, .cv-section ul { margin: 0; padding-left: 0; list-style: none; }
.cv-item ul li {
    font-size: 0.84rem;
    color: var(--text-dim);
    line-height: 1.65;
    margin-bottom: 3px;
    padding-left: 16px;
    position: relative;
}
.cv-item ul li::before {
    content: "·";
    position: absolute;
    left: 4px;
    color: var(--accent);
    font-size: 1rem;
    line-height: 1.65;
    font-weight: 700;
}
.cv-section > p { font-size: 0.82rem; color: var(--text-dim); line-height: 1.6; }
.cv-summary-footer {
    margin-top: 10px;
    font-size: 0.76rem;
    color: var(--text-soft);
    font-style: italic;
}

/* Skills Grid */
.cv-skills-grid { display: flex; flex-direction: column; gap: 10px; }
.cv-skill-block {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 16px 18px;
}
.cv-skill-block h3 {
    font-size: 0.74rem;
    font-weight: 600;
    color: var(--accent);
    margin-bottom: 6px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}
.cv-skill-block p {
    font-size: 0.82rem;
    color: var(--text-dim);
    line-height: 1.55;
    margin: 0;
}

/* Bold numbers */
.cv-item ul li strong {
    color: var(--number-color);
    font-weight: 600;
}

/* ===== Desktop (min-width: 600px) ===== */
@media (min-width: 600px) {
    /* General */
    header { padding: 80px 24px 48px; }
    .tagline { font-size: 0.95rem; }

    /* Article grid */
    .article-grid {
        grid-template-columns: 1fr 1fr;
        gap: 16px;
    }

    /* Hero desktop */
    .hero {
        padding: 120px 24px 64px;
        max-width: 720px;
        margin: 0 auto;
    }
    .hero-title { font-size: 3.4rem; letter-spacing: 0.06em; margin-bottom: 24px; }
    .hero-sub { font-size: 1.05rem; margin-bottom: 32px; }
    .hero-body { font-size: 0.9rem; margin-bottom: 20px; }
    .hero-body--tight { margin-top: -2px; }
    .hero-nav {
        flex-direction: row;
        gap: 14px;
    }
    .hero-link { flex: 1; padding: 22px 24px; }
    .hero-link:hover { border-color: var(--accent); transform: translateY(-1px); }
    .hero-link-icon { font-size: 1.75rem; }
    .hero-link-text strong { font-size: 1rem; }
    .hero-link-text small { font-size: 0.78rem; }

    /* Feature cards desktop */
    .feature-cards {
        flex-direction: row;
        gap: 10px;
        margin-top: 14px;
    }
    .feature-card { flex: 1; padding: 14px 18px; }
    .feature-card-icon { font-size: 1.2rem; }
    .feature-card-text strong { font-size: 0.85rem; }
    .feature-card-text small { font-size: 0.72rem; }

    .author-section { padding: 0 24px 32px; }

    /* CV desktop */
    .cv-main { padding: 0 24px 56px; }
    .cv-lang-toggle { margin-top: 12px; }
    .cv-avatar {
        width: 120px;
        height: 120px;
    }
    .back-link-fixed {
        top: 22px;
        left: 28px;
    }

    footer { padding: 24px 24px 40px; }
}

/* ===== Hero: Sub-nav (about, feedback, cv) ===== */
.hero-sub-nav {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 8px;
}
.hero-sub-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 16px;
    border-radius: 8px;
    font-size: 0.82rem;
    color: var(--text-dim);
    text-decoration: none;
    background: transparent;
    border: 1px solid var(--border);
    transition: all 0.15s;
}
.hero-sub-link:hover { border-color: var(--accent); color: var(--accent); }

.hero-bottom-tagline {
    margin-top: 32px;
    padding: 16px 0;
    font-size: 0.82rem;
    color: var(--text-soft);
    font-style: italic;
    border-top: 1px solid var(--border);
}

/* ===== About Page ===== */
.about-page {
    flex: 1;
    padding: 20px 20px 48px;
}
.about-letter {
    max-width: 680px;
    margin: 0 auto;
}
.about-letter h1 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 32px;
    color: var(--text);
}
.about-block {
    margin-bottom: 36px;
}
.about-block h2 {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--accent);
    margin-bottom: 12px;
}
.about-block p {
    font-size: 0.9rem;
    line-height: 1.75;
    color: var(--text-dim);
    margin-bottom: 10px;
}
.about-block p strong { color: var(--text); }
.about-block ol {
    padding-left: 20px;
    margin: 8px 0;
}
.about-block ol li {
    font-size: 0.88rem;
    line-height: 1.7;
    color: var(--text-dim);
    margin-bottom: 6px;
}
.about-block ol li strong { color: var(--text); }

.about-section-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 18px 20px;
    margin-bottom: 14px;
}
.about-section-card h3 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 8px;
}
.about-section-card p {
    font-size: 0.85rem;
    line-height: 1.7;
    color: var(--text-dim);
    margin-bottom: 6px;
}
.about-section-card p:last-child { margin-bottom: 0; }

.about-stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    margin-top: 20px;
}
.about-stat {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 24px 16px;
    text-align: center;
    transition: border-color 0.2s;
}
.about-stat:hover { border-color: var(--accent-dim); }
.about-stat-num {
    display: block;
    font-size: 2rem;
    font-weight: 800;
    color: var(--accent);
    line-height: 1.2;
    margin-bottom: 6px;
}
.about-stat-label {
    display: block;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 4px;
}
.about-stat-desc {
    display: block;
    font-size: 0.8rem;
    color: var(--text-dim);
}

.about-cta {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 24px 20px;
    margin-top: 40px;
}
.about-cta h2 { color: var(--text); }
.about-cta a {
    color: var(--accent);
    text-decoration: none;
    font-weight: 600;
}
.about-cta a:hover { text-decoration: underline; }
.about-signature {
    margin-top: 20px;
    font-size: 0.95rem;
    color: var(--text) !important;
    font-weight: 500;
}

/* ===== Feedback Page ===== */
.feedback-page {
    flex: 1;
    padding: 20px 20px 48px;
}
.feedback-container {
    max-width: 560px;
    margin: 0 auto;
}
.feedback-container h1 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--text);
}
.feedback-intro {
    font-size: 0.88rem;
    color: var(--text-dim);
    line-height: 1.65;
    margin-bottom: 28px;
}

.feedback-form {
    display: flex;
    flex-direction: column;
    gap: 14px;
}
.feedback-form label {
    font-size: 0.85rem;
    color: var(--text-dim);
    font-weight: 500;
    margin-bottom: -8px;
}
.feedback-form label .optional { color: var(--text-soft); font-weight: 400; font-size: 0.78rem; }
.feedback-form label .required { color: var(--red); }
.feedback-form input,
.feedback-form textarea {
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 12px 14px;
    color: var(--text);
    font-size: 0.92rem;
    font-family: inherit;
    outline: none;
    transition: border 0.15s;
}
.feedback-form input:focus,
.feedback-form textarea:focus { border-color: var(--accent); }
.feedback-form input::placeholder,
.feedback-form textarea::placeholder { color: var(--text-soft); font-size: 0.85rem; }
.feedback-form textarea { resize: vertical; min-height: 120px; }

.feedback-char-count {
    text-align: right;
    font-size: 0.72rem;
    color: var(--text-soft);
    margin-top: -8px;
}

.feedback-submit {
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 8px;
    padding: 14px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    min-height: 44px;
    transition: background 0.15s;
    margin-top: 4px;
}
.feedback-submit:hover { background: var(--accent-dim); }

.feedback-error {
    background: rgba(248, 113, 113, 0.1);
    border: 1px solid var(--red);
    border-radius: 8px;
    padding: 10px 16px;
    color: var(--red);
    font-size: 0.85rem;
}

.feedback-success {
    text-align: center;
    padding: 40px 20px;
}
.feedback-success-icon { font-size: 3rem; margin-bottom: 16px; }
.feedback-success h2 {
    font-size: 1.2rem;
    color: var(--text);
    margin-bottom: 10px;
}
.feedback-success p {
    font-size: 0.88rem;
    color: var(--text-dim);
    line-height: 1.6;
    margin-bottom: 24px;
}
.feedback-back-btn {
    display: inline-block;
    padding: 10px 28px;
    background: var(--accent);
    color: #fff;
    border-radius: 8px;
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 600;
    transition: background 0.15s;
}
.feedback-back-btn:hover { background: var(--accent-dim); }

/* ===== Admin: Feedback Table ===== */
.admin-feedback-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.82rem;
    margin-top: 8px;
}
.admin-feedback-table th,
.admin-feedback-table td {
    text-align: left;
    padding: 8px 10px;
    border-bottom: 1px solid var(--border);
    vertical-align: top;
}
.admin-feedback-table th {
    color: var(--text-soft);
    font-weight: 600;
    font-size: 0.72rem;
    text-transform: uppercase;
    letter-spacing: 0.04em;
}
.admin-feedback-table td { color: var(--text-dim); line-height: 1.5; }
.admin-feedback-table tbody tr:hover { background: var(--card-hover); }
.fb-unread { font-weight: 600; color: var(--accent); }
.fb-msg { max-width: 280px; word-break: break-word; }

/* ===== Desktop additions ===== */
@media (min-width: 600px) {
    .hero-sub-nav { gap: 12px; }
    .hero-sub-link { padding: 10px 20px; font-size: 0.85rem; }
    .hero-bottom-tagline { font-size: 0.85rem; }
    .about-letter h1 { font-size: 1.8rem; }
    .about-block h2 { font-size: 1.1rem; }
    .about-block p { font-size: 0.95rem; }
    .about-section-card { padding: 22px 28px; }
    .about-section-card h3 { font-size: 0.95rem; }
    .about-section-card p { font-size: 0.9rem; }
    .about-cta { padding: 28px 28px; }
    .about-stats { grid-template-columns: repeat(2, 1fr); }
    .about-stat-num { font-size: 1.6rem; }
    .feedback-container h1 { font-size: 1.8rem; }
    .feedback-intro { font-size: 0.95rem; }
}

/* ===== Quiz Page ===== */
.quiz-page {
    flex: 1;
    padding: 20px 20px 48px;
}

.quiz-header {
    max-width: 680px;
    margin: 0 auto 20px;
    text-align: center;
}
.quiz-header h1 {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 6px;
}
.quiz-header p {
    font-size: 0.82rem;
    color: var(--text-dim);
}

.quiz-empty {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-dim);
    font-size: 0.9rem;
}

/* Quiz Form */
.quiz-form {
    max-width: 680px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 14px;
}

/* Quiz Card */
.quiz-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 18px 20px;
}
.quiz-card-head {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 10px;
}
.quiz-card-num {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: var(--accent);
    color: #fff;
    font-size: 0.72rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}
.quiz-card-type {
    font-size: 0.7rem;
    color: var(--text-soft);
    background: rgba(124, 138, 255, 0.08);
    padding: 2px 8px;
    border-radius: 4px;
}
.quiz-card-question {
    font-size: 0.9rem;
    color: var(--text);
    line-height: 1.6;
    margin-bottom: 12px;
    font-weight: 500;
}

/* Quiz Options */
.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 6px;
}
.quiz-opt {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    padding: 8px 12px;
    border-radius: 8px;
    cursor: pointer;
    transition: background 0.15s;
    -webkit-tap-highlight-color: transparent;
}
.quiz-opt:hover { background: var(--card-hover); }
.quiz-opt input { display: none; }
.quiz-opt-mark {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    border: 2px solid var(--border);
    flex-shrink: 0;
    margin-top: 2px;
    transition: border-color 0.15s, background 0.15s;
    display: flex;
    align-items: center;
    justify-content: center;
}
.quiz-opt input[type="checkbox"] ~ .quiz-opt-mark {
    border-radius: 4px;
}
.quiz-opt input:checked ~ .quiz-opt-mark {
    border-color: var(--accent);
    background: var(--accent);
}
.quiz-opt input:checked ~ .quiz-opt-mark::after {
    content: "";
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: #fff;
}
.quiz-opt input[type="checkbox"]:checked ~ .quiz-opt-mark::after {
    border-radius: 1px;
    width: 7px;
    height: 4px;
    background: transparent;
    border-left: 2px solid #fff;
    border-bottom: 2px solid #fff;
    transform: rotate(-45deg) translate(1px, -1px);
}
.quiz-opt-text {
    font-size: 0.85rem;
    color: var(--text-dim);
    line-height: 1.5;
    flex: 1;
}
.quiz-opt-text strong { color: var(--text-soft); font-weight: 600; margin-right: 2px; }
.quiz-opt input:checked ~ .quiz-opt-text { color: var(--text); }

/* Submit Button */
.quiz-submit-btn {
    display: block;
    width: 100%;
    max-width: 680px;
    margin: 8px auto 0;
    padding: 14px;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 700;
    cursor: pointer;
    transition: background 0.15s;
    min-height: 44px;
}
.quiz-submit-btn:hover { background: var(--accent-dim); }

/* ─── Results ─── */
.quiz-result {
    max-width: 680px;
    margin: 0 auto;
}

.quiz-score-card {
    text-align: center;
    padding: 32px 20px;
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    margin-bottom: 24px;
}
.quiz-score-ring {
    display: flex;
    align-items: baseline;
    justify-content: center;
    gap: 2px;
}
.quiz-score-num {
    font-size: 3.5rem;
    font-weight: 800;
    color: var(--accent);
    line-height: 1;
}
.quiz-score-div {
    font-size: 1.5rem;
    color: var(--text-soft);
    margin: 0 2px;
}
.quiz-score-total {
    font-size: 2rem;
    font-weight: 600;
    color: var(--text-dim);
}
.quiz-score-label {
    margin-top: 12px;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text);
}

/* Review Cards */
.quiz-review {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-bottom: 24px;
}
.quiz-review-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 16px 18px;
}
.quiz-review--ok { border-left: 3px solid var(--green); }
.quiz-review--fail { border-left: 3px solid var(--red); }
.quiz-review-q {
    display: flex;
    align-items: flex-start;
    gap: 6px;
    font-size: 0.88rem;
    line-height: 1.55;
    color: var(--text);
    margin-bottom: 8px;
}
.quiz-review-idx { color: var(--text-soft); font-weight: 600; flex-shrink: 0; }
.quiz-review-badge {
    font-size: 0.65rem;
    background: rgba(124, 138, 255, 0.1);
    color: var(--text-soft);
    padding: 1px 6px;
    border-radius: 4px;
    white-space: nowrap;
    margin-left: auto;
    flex-shrink: 0;
}
.quiz-review-answers {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    margin-bottom: 8px;
    font-size: 0.78rem;
}
.quiz-review-wrong { color: var(--red); }
.quiz-review-right { color: var(--green); font-weight: 600; }
.quiz-review-explanation {
    font-size: 0.78rem;
    color: var(--text-dim);
    line-height: 1.55;
    background: rgba(124, 138, 255, 0.06);
    padding: 8px 12px;
    border-radius: 6px;
}

/* Quiz Actions */
.quiz-actions {
    display: flex;
    gap: 10px;
    justify-content: center;
    flex-wrap: wrap;
}
.quiz-retry-btn, .quiz-home-btn, .quiz-back-btn {
    display: inline-block;
    padding: 10px 24px;
    border-radius: 8px;
    font-size: 0.88rem;
    font-weight: 600;
    text-decoration: none;
    transition: background 0.15s;
    min-height: 44px;
    display: inline-flex;
    align-items: center;
}
.quiz-retry-btn {
    background: var(--accent);
    color: #fff;
}
.quiz-retry-btn:hover { background: var(--accent-dim); }
.quiz-home-btn, .quiz-back-btn {
    background: var(--card-bg);
    color: var(--text-dim);
    border: 1px solid var(--border);
}
.quiz-home-btn:hover, .quiz-back-btn:hover { border-color: var(--accent); color: var(--accent); }

@media (min-width: 600px) {
    .quiz-header h1 { font-size: 1.6rem; }
    .quiz-header p { font-size: 0.88rem; }
    .quiz-card { padding: 22px 28px; }
    .quiz-card-question { font-size: 0.95rem; }
    .quiz-opt { padding: 10px 14px; }
    .quiz-opt-text { font-size: 0.9rem; }
    .quiz-score-card { padding: 40px 20px; }
    .quiz-score-num { font-size: 4.5rem; }
    .quiz-review-card { padding: 18px 22px; }
    .quiz-review-q { font-size: 0.92rem; }
}

/* ===== Print ===== */
@media print {
    .theme-toggle, .back-link, .back-link-fixed, .cv-lang-toggle, footer, header .tagline { display: none; }
    body { background: #fff; color: #000; font-size: 11pt; }
    .cv-main { max-width: 100%; }
    .cv-content { display: block !important; }
    .cv-section h2 { border-bottom-color: #000; color: #000; }
    .cv-item ul li { color: #333; }
    .cv-item-header strong { color: #000; }
    .cv-summary { border-left-color: #000; }
    .cv-summary p { color: #111; }
}