:root {
      --blue: #2563EB; --blue-light: #EFF6FF; --blue-mid: #DBEAFE;
      --red: #DC2626; --red-light: #FEF2F2; --red-mid: #FEE2E2;
      --green: #16A34A; --green-light: #F0FDF4;
      --border: #E5E7EB; --text: #111827; --muted: #6B7280;
      --card: #ffffff; --bg: #F8FAFC;
    }
    body { background: var(--bg); }

    .lang-tabs { display: flex; gap: 8px; margin-bottom: 24px; flex-wrap: wrap; }
    .lang-tab {
      padding: 9px 22px; border-radius: 999px;
      border: 1.5px solid var(--border); background: #fff;
      color: var(--muted); font-size: 13px; font-weight: 600;
      cursor: pointer; transition: all .15s; white-space: nowrap;
    }
    .lang-tab.on { background: var(--blue); color: #fff; border-color: var(--blue); box-shadow: 0 2px 8px rgba(37,99,235,.25); }
    .lang-body { display: none; }
    .lang-body.on { display: flex; flex-direction: column; gap: 16px; }

    .sec-header { display: flex; align-items: center; gap: 10px; margin-bottom: 18px; }
    .sec-icon { width: 36px; height: 36px; border-radius: 10px; display: flex; align-items: center; justify-content: center; font-size: 18px; flex-shrink: 0; }
    .sec-title { font-size: 15px; font-weight: 700; color: var(--text); }
    .sec-sub { font-size: 12px; color: var(--muted); margin-top: 2px; }

    .t-card { background: var(--card); border: 1px solid var(--border); border-radius: 18px; padding: 22px; box-shadow: 0 1px 8px rgba(0,0,0,.05); }

    .guide-card { background: var(--card); border: 1px solid var(--border); border-radius: 18px; overflow: hidden; box-shadow: 0 1px 8px rgba(0,0,0,.05); }
    .guide-head { background: linear-gradient(135deg,#FEF2F2 0%,#fff 100%); border-bottom: 1px solid var(--red-mid); padding: 16px 20px; display: flex; align-items: center; gap: 10px; }
    .guide-head-title { font-size: 14px; font-weight: 700; color: #991B1B; }
    .guide-head-sub { font-size: 12px; color: #B91C1C; margin-top: 2px; }
    .guide-body { padding: 18px 20px; display: flex; flex-direction: column; gap: 16px; }
    .guide-section-title { font-size: 11px; font-weight: 700; color: var(--muted); text-transform: uppercase; letter-spacing: .7px; margin-bottom: 10px; }
    .guide-divider { border: none; border-top: 1px solid var(--border); }

    .guide-row { display: flex; gap: 10px; align-items: flex-start; font-size: 13.5px; color: #374151; line-height: 1.6; margin-bottom: 8px; }
    .guide-row:last-child { margin-bottom: 0; }
    .guide-icon { font-size: 14px; flex-shrink: 0; margin-top: 2px; }

    .sub-steps { margin-top: 8px; display: flex; flex-direction: column; gap: 6px; }
    .sub-step { display: flex; gap: 6px; align-items: flex-start; font-size: 13px; color: #1F2937; line-height: 1.5; flex-wrap: wrap; }
    .sub-step-arrow { color: #6B7280; font-size: 14px; flex-shrink: 0; margin-top: 1px; font-weight: 300; }
    .sub-step-text { flex: 1; }

    .rule-row { display: flex; gap: 10px; align-items: flex-start; font-size: 13px; color: #6B7280; line-height: 1.6; margin-bottom: 6px; }
    .rule-row:last-child { margin-bottom: 0; }

    .steps { display: flex; flex-direction: column; }
    .step { display: flex; gap: 14px; align-items: flex-start; padding: 16px 0; border-bottom: 1px solid #F3F4F6; }
    .step:last-child { border-bottom: none; padding-bottom: 0; }
    .step:first-child { padding-top: 0; }
    .step-num { min-width: 28px; height: 28px; background: var(--blue); color: #fff; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-size: 12px; font-weight: 700; flex-shrink: 0; margin-top: 1px; }
    .step-title { font-size: 14px; font-weight: 700; color: var(--text); margin-bottom: 5px; }
    .step-desc { font-size: 13px; color: #4B5563; line-height: 1.65; }

    .info-block { background: var(--blue-light); border: 1px solid var(--blue-mid); border-radius: 12px; padding: 12px 14px; margin-top: 10px; }
    .info-block-title { font-size: 12px; font-weight: 700; color: #1D4ED8; margin-bottom: 8px; }

    .link-example { border-radius: 9px; padding: 9px 12px; margin-top: 6px; }
    .link-example.ok { background: var(--green-light); }
    .link-example.bad { background: var(--red-light); margin-top: 6px; }
    .link-label { font-size: 11px; font-weight: 700; margin-bottom: 3px; display: block; }
    .link-example.ok .link-label { color: #166534; }
    .link-example.bad .link-label { color: #991B1B; }
    .link-url { font-family: monospace; font-size: 11.5px; word-break: break-all; display: block; }
    .link-example.ok .link-url { color: #14532D; }
    .link-example.bad .link-url { color: #991B1B; text-decoration: line-through; }

    .video-slot { background: #fff; border: 1.5px dashed var(--border); border-radius: 16px; padding: 40px 20px; text-align: center; color: var(--muted); margin-bottom: 24px; }
    .video-slot .vi { font-size: 36px; margin-bottom: 10px; }
    .video-slot p { font-size: 13px; margin: 0; }
    .video-embed { border-radius: 14px; overflow: hidden; margin-bottom: 24px; aspect-ratio: 16/9; background: #000; display: none; }
    .video-embed iframe, .video-embed video { width: 100%; height: 100%; border: none; }