/* ——— THEME DEFINITIONS ——— */

  /* DARK 1 — Midnight (deep dark) */
  .tabs-widget[data-theme="midnight"] {
    --tw-bg: #0b0c10;
    --tw-surface: #141519;
    --tw-surface2: #1c1d24;
    --tw-border: #27282f;
    --tw-text: #eae8e3;
    --tw-dim: #807e88;
    --tw-bar-bg: rgba(11, 12, 16, 0.82);
    --tw-bar-text: #807e88;
    --tw-bar-border: #27282f;
    --tw-bar-hover: #eae8e3;
    --tw-a1: #e8b84b;
    --tw-a2: #d4694e;
    --tw-a3: #56b895;
    --tw-a4: #6a7de8;
    --tw-a5: #b86ad4;
    --tw-a6: #e0895a;
    --tw-hero-glow: rgba(232,184,75,0.06);
    --tw-active-text: #0b0c10;
  }

  /* DARK 2 — Charcoal (warm dark gray) */
  .tabs-widget[data-theme="charcoal"] {
    --tw-bg: #1a1a1f;
    --tw-surface: #222228;
    --tw-surface2: #2b2b32;
    --tw-border: #3a3a42;
    --tw-text: #e5e3de;
    --tw-dim: #8e8c95;
    --tw-bar-bg: rgba(26, 26, 31, 0.85);
    --tw-bar-text: #8e8c95;
    --tw-bar-border: #3a3a42;
    --tw-bar-hover: #e5e3de;
    --tw-a1: #f0c75e;
    --tw-a2: #e07558;
    --tw-a3: #5cc9a0;
    --tw-a4: #7b8ef5;
    --tw-a5: #c47de0;
    --tw-a6: #e8956a;
    --tw-hero-glow: rgba(240,199,94,0.05);
    --tw-active-text: #1a1a1f;
  }

  /* DARK 3 — Slate (cool dark gray) */
  .tabs-widget[data-theme="slate"] {
    --tw-bg: #23272e;
    --tw-surface: #2c313a;
    --tw-surface2: #353b45;
    --tw-border: #454c58;
    --tw-text: #dfe1e5;
    --tw-dim: #929aaa;
    --tw-bar-bg: rgba(35, 39, 46, 0.85);
    --tw-bar-text: #929aaa;
    --tw-bar-border: #454c58;
    --tw-bar-hover: #dfe1e5;
    --tw-a1: #f5d06a;
    --tw-a2: #e8805f;
    --tw-a3: #62d4ab;
    --tw-a4: #889bff;
    --tw-a5: #cf8ae8;
    --tw-a6: #f0a070;
    --tw-hero-glow: rgba(245,208,106,0.05);
    --tw-active-text: #23272e;
  }

  /* LIGHT 1 — Silver (medium light gray) */
  .tabs-widget[data-theme="silver"] {
    --tw-bg: #e8e9ed;
    --tw-surface: #f0f1f4;
    --tw-surface2: #e2e3e8;
    --tw-border: #d0d1d8;
    --tw-text: #1e1f25;
    --tw-dim: #5e6070;
    --tw-bar-bg: rgba(232, 233, 237, 0.88);
    --tw-bar-text: #5e6070;
    --tw-bar-border: #d0d1d8;
    --tw-bar-hover: #1e1f25;
    --tw-a1: #c9960e;
    --tw-a2: #c0502e;
    --tw-a3: #1d8f6a;
    --tw-a4: #4a5ec0;
    --tw-a5: #9040b8;
    --tw-a6: #c06828;
    --tw-hero-glow: rgba(201,150,14,0.06);
    --tw-active-text: #ffffff;
  }

  /* LIGHT 2 — Cloud (soft warm light) */
  .tabs-widget[data-theme="cloud"] {
    --tw-bg: #f2f0ec;
    --tw-surface: #faf9f6;
    --tw-surface2: #eceae5;
    --tw-border: #ddd9d2;
    --tw-text: #26241e;
    --tw-dim: #706c62;
    --tw-bar-bg: rgba(242, 240, 236, 0.88);
    --tw-bar-text: #706c62;
    --tw-bar-border: #ddd9d2;
    --tw-bar-hover: #26241e;
    --tw-a1: #b88508;
    --tw-a2: #b84828;
    --tw-a3: #1a8560;
    --tw-a4: #4555b0;
    --tw-a5: #8838a8;
    --tw-a6: #b06020;
    --tw-hero-glow: rgba(184,133,8,0.05);
    --tw-active-text: #ffffff;
  }

  /* LIGHT 3 — Pearl (clean white) */
  .tabs-widget[data-theme="pearl"] {
    --tw-bg: #ffffff;
    --tw-surface: #f7f7f8;
    --tw-surface2: #eeeff2;
    --tw-border: #dcdde2;
    --tw-text: #1a1b20;
    --tw-dim: #6b6d78;
    --tw-bar-bg: rgba(255, 255, 255, 0.88);
    --tw-bar-text: #6b6d78;
    --tw-bar-border: #dcdde2;
    --tw-bar-hover: #1a1b20;
    --tw-a1: #c08a00;
    --tw-a2: #b54228;
    --tw-a3: #138058;
    --tw-a4: #3d52b5;
    --tw-a5: #7e32a5;
    --tw-a6: #a85818;
    --tw-hero-glow: rgba(192,138,0,0.05);
    --tw-active-text: #ffffff;
  }

  /* LIGHT 4 — Ivory (warm white + dark nav) */
  .tabs-widget[data-theme="ivory"] {
    --tw-bg: #fdfcf9;
    --tw-surface: #f5f3ee;
    --tw-surface2: #edeae4;
    --tw-border: #ddd9d0;
    --tw-text: #2a2620;
    --tw-dim: #7a7568;
    --tw-bar-bg: rgba(42, 42, 48, 0.96);
    --tw-bar-text: #b0aead;
    --tw-bar-border: rgba(255,255,255,0.08);
    --tw-bar-hover: #f0eeea;
    --tw-a1: #d4960a;
    --tw-a2: #c24e30;
    --tw-a3: #18966a;
    --tw-a4: #4a60c0;
    --tw-a5: #8e3eb5;
    --tw-a6: #c06020;
    --tw-hero-glow: rgba(212,150,10,0.05);
    --tw-active-text: #ffffff;
  }

  /* LIGHT 5 — Frost (cool white + dark nav) */
  .tabs-widget[data-theme="frost"] {
    --tw-bg: #f8f9fc;
    --tw-surface: #f0f1f6;
    --tw-surface2: #e6e8ee;
    --tw-border: #d4d6de;
    --tw-text: #1c1e28;
    --tw-dim: #686c7a;
    --tw-bar-bg: rgba(36, 38, 48, 0.96);
    --tw-bar-text: #a8aab8;
    --tw-bar-border: rgba(255,255,255,0.08);
    --tw-bar-hover: #FFD801;
    --tw-a1: #779D41;
    --tw-a2: #c84a2a;
    --tw-a3: #109060;
    --tw-a4: #4558c8;
    --tw-a5: #8838b5;
    --tw-a6: #009DE6;
    --tw-hero-glow: rgba(184,138,16,0.05);
    --tw-active-text: #ffffff;
  }

  /* LIGHT 6 — Linen (neutral white + dark nav) */
  .tabs-widget[data-theme="linen"] {
    --tw-bg: #fbfaf8;
    --tw-surface: #f3f2ef;
    --tw-surface2: #eae9e5;
    --tw-border: #d8d7d2;
    --tw-text: #222220;
    --tw-dim: #74736e;
    --tw-bar-bg: rgba(38, 38, 40, 0.96);
    --tw-bar-text: #acacaa;
    --tw-bar-border: rgba(255,255,255,0.08);
    --tw-bar-hover: #eceae6;
    --tw-a1: #c89000;
    --tw-a2: #be4828;
    --tw-a3: #158860;
    --tw-a4: #4050b8;
    --tw-a5: #8235a8;
    --tw-a6: #b05a18;
    --tw-hero-glow: rgba(200,144,0,0.05);
    --tw-active-text: #ffffff;
  }


  /* ——— All styles scoped under .tabs-widget ——— */
  .tabs-widget {
    direction: rtl;
    text-align: right;
    color: var(--tw-text);
    line-height: 1.75;
    position: relative;
    max-width: 100%;
    background: var(--tw-bg);
    transition: background 0.4s ease, color 0.4s ease;
  }

  .tabs-widget *, .tabs-widget *::before, .tabs-widget *::after {
    box-sizing: border-box;
    margin: 0;
    / *padding: 0; */
  }

  /* grain texture */
  .tabs-widget::before {
    content: '';
    position: absolute;
    inset: 0;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.8' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.035'/%3E%3C/svg%3E");
    background-size: 200px;
    pointer-events: none;
    z-index: 10;
  }

  /* ——— Hero ——— */
  .tw-hero {
    padding: 5px 32px 36px;
    text-align: center;
    position: relative;
    background: radial-gradient(ellipse at 50% 0%, var(--tw-hero-glow) 0%, transparent 60%);
  }

  .tw-hero h1 {
    font-size: clamp(2rem, 5vw, 3.6rem);
    font-weight: 400;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, var(--tw-text) 30%, var(--tw-a1));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 12px;
    animation: twFadeUp 1.0s ease both;
  }

  .tw-hero p {
    color: var(--tw-dim);
    font-weight: 300;
    font-size: 1rem;
    max-width: 440px;
    margin: 0 auto;
    animation: twFadeUp 0.7s 0.12s ease both;
  }

  @keyframes twFadeUp {
    from { opacity: 0; transform: translateY(16px); }
    to   { opacity: 1; transform: translateY(0); }
  }

/* ——— Tab bar ——— */
.tw-tab-bar-wrap {
  position: sticky;
  top: 30px; /* Default for width < 600px */
  z-index: 100;
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  background: var(--tw-bar-bg);
  border: 1px solid var(--tw-bar-border);
  border-radius: 14px;
  padding: 0 4px;
  max-width: 100%;
  margin: 0 auto;
  transition: box-shadow 0.3s, background 0.4s ease;
}

/* ——— Responsive Logic ——— */
@media (min-width: 801px) {
  .tw-tab-bar-wrap {
    top: 0px; /* Applied if width is larger than 600px */
  }
}




  .tw-tab-bar-wrap.tw-scrolled {
    box-shadow: 0 8px 32px rgba(0,0,0,0.18);
  }

  .tw-tab-bar {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 4px;
    max-width: 960px;
    margin: 0 auto;
    padding: 4px 0;
  }

  .tw-tab-btn {
    all: unset;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 5px;
    padding: 5px 5px;
    border-radius: 10px;
    font-size: 0.88rem;
    font-weight: 800;
    color: var(--tw-bar-text);
    white-space: nowrap;
    transition: all 0.62s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    flex-shrink: 0;
    position: relative;
  }

  .tw-tab-btn .tw-ico {
    width: 22px; height: 22px;
    display: flex; align-items: center; justify-content: center;
    border-radius: 6px;
    font-size: 0.72rem;
    transition: all 0.32s ease;
    background: rgba(128,128,128,0.15);
  }

  .tw-tab-btn:hover { color: var(--tw-bar-hover); background: rgba(128,128,128,0.1); }

  .tw-tab-btn.tw-active { color: var(--tw-active-text); font-weight: 600; }
  .tw-tab-btn.tw-active .tw-ico { background: rgba(0,0,0,0.15); }

  .tw-tab-btn[data-tab="0"].tw-active { background: var(--tw-a1); }
  .tw-tab-btn[data-tab="1"].tw-active { background: var(--tw-a2); }
  .tw-tab-btn[data-tab="2"].tw-active { background: var(--tw-a3); }
  .tw-tab-btn[data-tab="3"].tw-active { background: var(--tw-a4); }
  .tw-tab-btn[data-tab="4"].tw-active { background: var(--tw-a5); }
  .tw-tab-btn[data-tab="5"].tw-active { background: var(--tw-a6); }

  /* ——— Content ——— */
  .tw-content {
    max-width: 100%;
    margin: 0 auto;
    padding: 44px 24px 100px;
    position: relative;
    z-index: 1;
  }

  .tw-panel { display: none; animation: twPanelIn 0.5s ease both; }
  .tw-panel.tw-visible { display: block; }

  @keyframes twPanelIn {
    from { opacity: 0; transform: translateY(20px); }
    to   { opacity: 1; transform: translateY(0); }
  }

  .tw-panel-head {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 30px;
  }

  .tw-badge {
    width: 46px; height: 46px;
    border-radius: 13px;
    display: flex; align-items: center; justify-content: center;
    font-size: 1.2rem;
    flex-shrink: 0;
    color: var(--tw-active-text);
  }

  .tw-panel[data-panel="0"] .tw-badge { background: var(--tw-a1); }
  .tw-panel[data-panel="1"] .tw-badge { background: var(--tw-a2); }
  .tw-panel[data-panel="2"] .tw-badge { background: var(--tw-a3); }
  .tw-panel[data-panel="3"] .tw-badge { background: var(--tw-a4); }
  .tw-panel[data-panel="4"] .tw-badge { background: var(--tw-a5); }
  .tw-panel[data-panel="5"] .tw-badge { background: var(--tw-a6); }

  .tw-panel-head h2 {
    font-size: 1.7rem;
    font-weight: 400;
  }

  .tw-panel-head .tw-sub {
    display: block;
    font-size: 0.8rem;
    color: var(--tw-dim);
    font-weight: 400;
    margin-top: 2px;
  }

  .tw-body { display: grid; gap: 18px; }

  .tw-card {
    background: var(--tw-surface);
    border: 1px solid var(--tw-border);
    border-radius: 14px;
    padding: 26px 28px;
    transition: transform 0.3s, border-color 0.3s, background 0.4s;
    text-align: right;
  }

  .tw-card:hover { transform: translateY(-2px); border-color: var(--tw-dim); }

  .tw-card h3 { font-size: 1.02rem; font-weight: 600; margin-bottom: 10px; }

  .tw-card p {
    font-weight: 300;
    color: var(--tw-dim);
    font-size: 0.91rem;
    line-height: 1.8;
  }

  /* stats */
  .tw-stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 12px; }

  .tw-stat {
    background: var(--tw-surface);
    border: 1px solid var(--tw-border);
    border-radius: 12px;
    padding: 20px;
    text-align: center;
    transition: transform 0.3s, background 0.4s;
  }

  .tw-stat:hover { transform: translateY(-2px); }

  .tw-stat .tw-num {
    font-size: 1.9rem;
    display: block;
    margin-bottom: 3px;
  }

  .tw-panel[data-panel="0"] .tw-num { color: var(--tw-a1); }
  .tw-panel[data-panel="3"] .tw-num { color: var(--tw-a4); }

  .tw-stat .tw-lbl {
    font-size: 0.76rem;
    color: var(--tw-dim);
    text-transform: uppercase;
    letter-spacing: 0.08em;
  }

  /* tags */
  .tw-tags { display: flex; flex-wrap: wrap; gap: 7px; margin-top: 10px; }

  .tw-tag {
    padding: 5px 13px;
    border-radius: 18px;
    font-size: 0.78rem;
    font-weight: 500;
    background: var(--tw-surface2);
    border: 1px solid var(--tw-border);
    color: var(--tw-dim);
    transition: all 0.25s;
  }

  .tw-tag:hover { color: var(--tw-text); border-color: var(--tw-dim); }

  /* ——— Images ——— */
  .tw-img-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }

  .tw-img-card {
    position: relative;
    border-radius: 14px;
    overflow: hidden;
    border: 1px solid var(--tw-border);
    background: var(--tw-surface);
    transition: transform 0.3s, border-color 0.3s, background 0.4s;
  }

  .tw-img-card:hover { transform: translateY(-2px); border-color: var(--tw-dim); }

  .tw-img-card img { width: 100%; height: 200px; object-fit: cover; display: block; }
  .tw-img-card .tw-img-caption { padding: 14px 18px; }
  .tw-img-card .tw-img-caption h4 { font-size: 0.92rem; font-weight: 600; margin-bottom: 4px; }
  .tw-img-card .tw-img-caption p { font-size: 0.82rem; color: var(--tw-dim); font-weight: 300; line-height: 1.6; }

  .tw-img-full {
    border-radius: 14px;
    overflow: hidden;
    border: 1px solid var(--tw-border);
    background: var(--tw-surface);
    transition: transform 0.3s, border-color 0.3s, background 0.4s;
  }

  .tw-img-full:hover { transform: translateY(-2px); border-color: var(--tw-dim); }

  .tw-img-full img { width: 100%; height: 320px; object-fit: cover; display: block; }
  .tw-img-full .tw-img-caption { padding: 18px 22px; }
  .tw-img-full .tw-img-caption h4 { font-size: 1rem; font-weight: 600; margin-bottom: 6px; }
  .tw-img-full .tw-img-caption p { font-size: 0.88rem; color: var(--tw-dim); font-weight: 300; line-height: 1.7; }

  /* ——— Video Player ——— */
  .tw-video-wrap {
    border-radius: 14px;
    overflow: hidden;
    border: 1px solid var(--tw-border);
    background: var(--tw-surface);
    transition: transform 0.3s, border-color 0.3s, background 0.4s;
  }

  .tw-video-wrap:hover { border-color: var(--tw-dim); }

  .tw-video-wrap video { width: 100%; display: block; background: #000; aspect-ratio: 16 / 9; }

  .tw-video-info { padding: 18px 22px; display: flex; align-items: flex-start; gap: 14px; }

  .tw-video-dot { width: 10px; height: 10px; border-radius: 50%; flex-shrink: 0; margin-top: 6px; }
  .tw-video-info h4 { font-size: 0.96rem; font-weight: 600; margin-bottom: 4px; }
  .tw-video-info p { font-size: 0.84rem; color: var(--tw-dim); font-weight: 300; line-height: 1.65; }

  .tw-video-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
  .tw-video-grid .tw-video-wrap video { height: 220px; object-fit: cover; aspect-ratio: auto; }

  /* timeline */
  .tw-timeline { position: relative; padding-right: 28px; }

  .tw-timeline::before {
    content: '';
    position: absolute;
    right: 6px; top: 6px; bottom: 6px;
    width: 2px;
    background: var(--tw-border);
    border-radius: 2px;
  }

  .tw-tl-item { position: relative; padding-bottom: 26px; }

  .tw-tl-item::before {
    content: '';
    position: absolute;
    right: -24px; top: 8px;
    width: 10px; height: 10px;
    border-radius: 50%;
    border: 2px solid var(--tw-a5);
    background: var(--tw-bg);
    transition: background 0.4s;
  }

  .tw-tl-item h4 { font-size: 0.93rem; font-weight: 600; margin-bottom: 3px; }
  .tw-tl-item .tw-date { font-size: 0.76rem; color: var(--tw-dim); margin-bottom: 5px; }
  .tw-tl-item p { color: var(--tw-dim); font-size: 0.88rem; font-weight: 300; }

  /* ——— FAQ Accordion ——— */
  .tw-faq-list { display: flex; flex-direction: column; gap: 10px; }

  .tw-faq-item {
    border: 1px solid var(--tw-border);
    border-radius: 12px;
    background: var(--tw-surface);
    overflow: hidden;
    transition: border-color 0.3s, background 0.4s;
  }

  .tw-faq-item:hover { border-color: var(--tw-dim); }
  .tw-faq-item.tw-faq-open { border-color: var(--tw-a6); }

  .tw-faq-question {
    all: unset;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 14px;
    width: 100%;
    padding: 18px 22px;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--tw-text);
    text-align: right;
    transition: background 0.25s;
  }

  .tw-faq-question:hover { background: var(--tw-surface2); }

  .tw-faq-question .tw-faq-icon {
    width: 28px; height: 28px;
    border-radius: 8px;
    background: var(--tw-surface2);
    display: flex; align-items: center; justify-content: center;
    flex-shrink: 0;
    font-size: 0.85rem;
    color: var(--tw-a6);
    transition: transform 0.35s cubic-bezier(0.4, 0, 0.2, 1), background 0.25s;
    font-weight: 400;
  }

  .tw-faq-open .tw-faq-question .tw-faq-icon {
    transform: rotate(45deg);
    background: var(--tw-a6);
    color: var(--tw-active-text);
  }

  .tw-faq-question span:last-child { flex: 1; line-height: 1.6; }

  .tw-faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s cubic-bezier(0.4, 0, 0.2, 1), padding 0.3s ease;
    padding: 0 22px;
  }

  .tw-faq-open .tw-faq-answer { max-height: 600px; padding: 0 22px 22px; }

  .tw-faq-answer-inner { padding-top: 10px; border-top: 1px solid var(--tw-border); }

  .tw-faq-answer p { font-weight: 300; color: var(--tw-dim); font-size: 0.9rem; line-height: 1.9; }

  /* responsive */
  @media (max-width: 640px) {
    .tw-hero { padding: 44px 18px 28px; }
    .tw-tab-btn { padding: 5px 5px; font-size: 0.82rem; }
    .tw-panel-head h2 { font-size: 1.35rem; }
    .tw-stats { grid-template-columns: 1fr 1fr; }
    .tw-img-grid { grid-template-columns: 1fr; }
    .tw-video-grid { grid-template-columns: 1fr; }
    .tw-img-card img { height: 160px; }
    .tw-img-full img { height: 220px; }
    .tw-faq-question { padding: 14px 16px; font-size: 0.88rem; }
    .tw-faq-answer { padding: 0 16px; }
    .tw-faq-open .tw-faq-answer { padding: 0 16px 16px; }
  }

  .tw-hero::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 50%;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--tw-border), transparent);
  }

  .f4-wrap {
    --bg-primary: #f0f1f6;
    --bg-secondary: #f8f9fc;
    --bg-card: #d3d6db;
    --bg-card-hover: #c8ccd2;
    --accent-blue: #1d4ed8;
    --accent-blue-light: #c7d6f5;
    --accent-orange: #c44b14;
    --accent-orange-light: #f5d9cb;
    --accent-green: #15803d;
    --accent-green-light: #c3e8d0;
    --accent-red: #b91c1c;
    --accent-red-light: #f0c9c9;
    --accent-yellow: #a16207;
    --accent-yellow-light: #ede0b3;
    --text-primary: #1a1d23;
    --text-secondary: #3e4554;
    --text-muted: #6b7280;
    --border-color: #c4c8ce;
    --border-dark: #b0b5bd;
    --shadow-sm: 0 1px 4px rgba(0,0,0,.08);
    --shadow-md: 0 4px 16px rgba(0,0,0,.1);
    --shadow-lg: 0 8px 30px rgba(0,0,0,.12);
  }

  .f4-wrap *, .f4-wrap *::before, .f4-wrap *::after { margin: 0; padding: 0; box-sizing: border-box; }

  .f4-wrap {
    font-family: 'Vazirmatn', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.9;
    overflow-x: hidden;
  }

  /* ── Hero ── */
  .f4-hero {
    position: relative;
    min-height: 55vh;
    display: flex;

    justify-content: center;
    text-align: center;
    padding: 2rem;
    overflow: hidden;
    /* GRADIENT on top, IMAGE underneath — replace the URL with your image path */
    background:
      linear-gradient(145deg, rgba(10,22,40,.93) 0%, rgba(15,36,71,.91) 30%, rgba(22,45,90,.89) 50%, rgba(26,58,110,.88) 70%, rgba(13,31,61,.93) 100%),
      url("YOUR-IMAGE-PATH-HERE.jpg") center / cover no-repeat;
    border: 1px solid rgba(80,140,255,.15);
    border-radius: 20px;
    margin: 12px;
  }
  .f4-hero::before {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: inherit;
    background:
      radial-gradient(ellipse 65% 55% at 25% 35%, rgba(56,120,255,.3) 0%, transparent 65%),
      radial-gradient(ellipse 55% 50% at 75% 55%, rgba(140,80,220,.2) 0%, transparent 60%),
      radial-gradient(ellipse 50% 45% at 50% 80%, rgba(0,200,180,.12) 0%, transparent 55%),
      radial-gradient(circle at 15% 80%, rgba(255,160,50,.1) 0%, transparent 40%);
  }
  .f4-hero::after {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: inherit;
    background:
      radial-gradient(circle at 70% 20%, rgba(100,180,255,.08) 0%, transparent 50%),
      radial-gradient(circle at 30% 70%, rgba(180,120,255,.06) 0%, transparent 45%);
    pointer-events: none;
  }
  .f4-hero-grid {
    position: absolute;
    inset: 0;
    border-radius: inherit;
    background-image:
      linear-gradient(rgba(150,200,255,.06) 1px, transparent 1px),
      linear-gradient(90deg, rgba(150,200,255,.06) 1px, transparent 1px);
    background-size: 60px 60px;
    mask-image: radial-gradient(ellipse 80% 70% at 50% 50%, black 20%, transparent 80%);
  }
  .f4-hero-content { position: relative; z-index: 2; max-width: 900px; }
  .f4-hero-badge {
    display: inline-block;
    padding: .35rem 1.2rem;
    border: 1.5px solid rgba(96,165,250,.5);
    border-radius: 50px;
    font-size: .8rem;
    color: #93c5fd;
    font-weight: 600;
    letter-spacing: .5px;
    margin-bottom: 1.5rem;
    background: rgba(30,64,175,.35);
    animation: f4FadeDown .8s ease-out;
  }
  .f4-hero h1 {
    font-size: clamp(2rem, 5vw, 3.6rem);
    font-weight: 900;
    line-height: 1.3;
    margin-bottom: 1rem;
    color: #eef2ff;
    animation: f4FadeDown 1s ease-out;
  }
  .f4-hero h1 span { color: #60a5fa; }
  .f4-hero p {
    font-size: clamp(1rem, 2vw, 1.2rem);
    color: rgba(200,215,240,.8);
    max-width: 650px;
    margin: 0 auto;
    animation: f4FadeDown 1.2s ease-out;
  }
  .f4-scroll-hint {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: .4rem;
    color: rgba(160,185,225,.6);
    font-size: .75rem;
    animation: f4Bounce 2s infinite;
  }
  .f4-scroll-hint .f4-arrow { width: 20px; height: 20px; border-left: 2px solid rgba(160,185,225,.5); border-bottom: 2px solid rgba(160,185,225,.5); transform: rotate(-45deg); }

  /* ── Container & Sections ── */
  .f4-container { max-width: 100%; margin: 0 auto; }

  .f4-wrap section {
    padding: 0;
    position: relative;
  }
  .f4-wrap section:nth-child(even of section) { background: var(--bg-secondary); }

  .f4-section-label {
    display: inline-flex;
    align-items: center;
    gap: .5rem;
    font-size: .78rem;
    font-weight: 700;
    color: var(--accent-blue);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: .8rem;
  }
  .f4-section-label .f4-line { width: 30px; height: 2.5px; background: var(--accent-blue); border-radius: 2px; }

  .f4-section-title {
    font-size: clamp(1.6rem, 3.5vw, 2.4rem);
    font-weight: 800;
    margin-bottom: 1.5rem;
    line-height: 1.4;
    color: var(--text-primary);
  }
  .f4-section-title em { font-style: normal; color: var(--accent-orange); }

  .f4-section-text {
    font-size: 1.02rem;
    color: var(--text-secondary);
    line-height: 2.1;
    max-width: 850px;
  }
  .f4-section-text + .f4-section-text { margin-top: 1rem; }
  .f4-section-text strong { color: var(--text-primary); }

  /* ── Diagram Cards ── */
  .f4-diagram-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 260px), 1fr));
    gap: 2rem;
    margin-top: 3rem;
  }
  .f4-diagram-card {
    background: var(--bg-primary);
    border: 1.5px solid var(--border-color);
    border-radius: 16px;
    padding: 2rem;
    position: relative;
    overflow: hidden;
    transition: transform .3s, box-shadow .3s;
  }
  .f4-diagram-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }

  .f4-diagram-card .f4-card-icon {
    width: 52px;
    height: 52px;
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    margin-bottom: 1.2rem;
  }
  .f4-diagram-card.f4-cyan .f4-card-icon { background: var(--accent-blue-light); color: var(--accent-blue); }
  .f4-diagram-card.f4-orange .f4-card-icon { background: var(--accent-orange-light); color: var(--accent-orange); }

  .f4-diagram-card h3 { font-size: 1.25rem; font-weight: 700; margin-bottom: .6rem; color: var(--text-primary); }
  .f4-diagram-card > p { font-size: .95rem; color: var(--text-muted); line-height: 1.9; }

  .f4-flow-steps {
    margin-top: 1.4rem;
    display: flex;
    flex-direction: column;
    gap: .6rem;
  }
  .f4-flow-step {
    display: flex;
    align-items: center;
    gap: .75rem;
    padding: .65rem 1rem;
    background: var(--bg-card);
    border-radius: 10px;
    font-size: .9rem;
    color: var(--text-secondary);
    border-right: 3px solid transparent;
    transition: background .2s;
  }
  .f4-diagram-card.f4-cyan .f4-flow-step { border-right-color: var(--accent-blue); }
  .f4-diagram-card.f4-orange .f4-flow-step { border-right-color: var(--accent-orange); }
  .f4-flow-step:hover { background: var(--bg-card-hover); }
  .f4-flow-step .f4-num {
    width: 26px;
    height: 26px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: .75rem;
    font-weight: 700;
    flex-shrink: 0;
  }
  .f4-diagram-card.f4-cyan .f4-num { background: var(--accent-blue-light); color: var(--accent-blue); }
  .f4-diagram-card.f4-orange .f4-num { background: var(--accent-orange-light); color: var(--accent-orange); }

  /* ── Component Detail Grid ── */
  .f4-comp-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(min(100%,300px),1fr));
    gap: 1.2rem;
    margin-top: 2rem;
  }
  .f4-comp-item {
    background: var(--bg-primary);
    border: 1.5px solid var(--border-color);
    border-radius: 14px;
    padding: 1.5rem;
    transition: border-color .3s, box-shadow .3s;
  }
  .f4-comp-item:hover { border-color: var(--accent-blue); box-shadow: var(--shadow-sm); }
  .f4-comp-item h4 { font-size: 1.05rem; font-weight: 700; margin-bottom: .4rem; color: var(--accent-blue); }
  .f4-comp-item p { font-size: .9rem; color: var(--text-secondary); line-height: 1.85; }

  /* ── Comparison Table ── */
  .f4-table-wrapper {
    margin-top: 2.5rem;
    overflow-x: auto;
    border-radius: 16px;
    border: 1.5px solid var(--border-color);
    background: var(--bg-primary);
    box-shadow: var(--shadow-sm);
    -webkit-overflow-scrolling: touch;
  }
  .f4-wrap table {
    width: 100%;
    min-width: 200px;
    border-collapse: collapse;
    font-size: .93rem;
  }
  .f4-wrap thead th {
    background: var(--bg-card);
    padding: 1rem 1.2rem;
    text-align: right;
    font-weight: 700;
    font-size: .95rem;
    color: var(--text-primary);
    border-bottom: 2px solid var(--border-dark);
    white-space: nowrap;
  }
  .f4-wrap thead th:first-child { border-radius: 0 14px 0 0; }
  .f4-wrap thead th:last-child { border-radius: 14px 0 0 0; }
  .f4-wrap tbody td {
    padding: .85rem 1.2rem;
    border-bottom: 1px solid var(--border-color);
    vertical-align: top;
    color: var(--text-secondary);
  }
  .f4-wrap tbody tr:last-child td { border-bottom: none; }
  .f4-wrap tbody tr:hover { background: var(--bg-secondary); }
  .f4-wrap td:first-child { font-weight: 600; color: var(--text-primary); white-space: nowrap; }

  /* ── Mobile card layout for comparison table ── */
  @media (max-width: 680px) {
    .f4-table-wrapper { border: none; box-shadow: none; background: transparent; border-radius: 0; }
    .f4-wrap table { min-width: 0; }
    .f4-wrap thead { display: none; }
    .f4-wrap tbody { display: flex; flex-direction: column; gap: 12px; }
    .f4-wrap tbody tr {
      display: flex;
      flex-direction: column;
      background: var(--bg-primary);
      border: 1.5px solid var(--border-color);
      border-radius: 14px;
      padding: 0;
      overflow: hidden;
      transition: box-shadow .3s;
    }
    .f4-wrap tbody tr:hover { background: var(--bg-primary); box-shadow: var(--shadow-md); }
    .f4-wrap tbody td {
      display: flex;
      align-items: baseline;
      gap: .5rem;
      padding: .7rem 1rem;
      border-bottom: 1px solid var(--border-color);
      white-space: normal;
    }
    .f4-wrap tbody td:last-child { border-bottom: none; }
    .f4-wrap td:first-child {
      white-space: normal;
      background: var(--bg-card);
      font-size: .88rem;
      font-weight: 700;
      color: var(--text-primary);
      padding: .65rem 1rem;
    }
    .f4-wrap tbody td:not(:first-child)::before {
      content: attr(data-label);
      font-size: .72rem;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: .5px;
      color: var(--text-muted);
      min-width: 72px;
      flex-shrink: 0;
    }
    .f4-wrap tbody td:not(:first-child) { font-size: .88rem; }
  }

  .f4-tick {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 26px;
    height: 26px;
    border-radius: 50%;
    font-size: .85rem;
    font-weight: 700;
  }
  .f4-tick.f4-yes { background: var(--accent-green-light); color: var(--accent-green); }
  .f4-tick.f4-no  { background: var(--accent-red-light);   color: var(--accent-red);   }
  .f4-tick.f4-mid { background: var(--accent-yellow-light); color: var(--accent-yellow); }

  /* ── Pros / Cons Columns ── */
  .f4-pro-con-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(min(100%,460px),1fr));
    gap: 2rem;
    margin-top: 2.5rem;
  }
  .f4-pro-con-card {
    background: var(--bg-primary);
    border: 1.5px solid var(--border-color);
    border-radius: 16px;
    padding: 2rem;
    box-shadow: var(--shadow-sm);
  }
  .f4-pro-con-card h3 { font-size: 1.15rem; font-weight: 700; margin-bottom: 1rem; display: flex; align-items: center; gap: .5rem; }
  .f4-pro-con-card ul { list-style: none; display: flex; flex-direction: column; gap: .6rem; }
  .f4-pro-con-card li {
    display: flex;
    align-items: flex-start;
    gap: .65rem;
    font-size: .93rem;
    color: var(--text-secondary);
    line-height: 1.8;
  }
  .f4-pro-con-card li .f4-icon {
    flex-shrink: 0;
    margin-top: .35rem;
    font-size: .85rem;
    font-weight: 700;
  }
  .f4-pro-con-card.f4-pros { border-top: 3px solid var(--accent-green); }
  .f4-pro-con-card.f4-pros h3 { color: var(--accent-green); }
  .f4-pro-con-card.f4-pros .f4-icon { color: var(--accent-green); }
  .f4-pro-con-card.f4-cons { border-top: 3px solid var(--accent-red); }
  .f4-pro-con-card.f4-cons h3 { color: var(--accent-red); }
  .f4-pro-con-card.f4-cons .f4-icon { color: var(--accent-red); }

  /* ── Use-Case Cards ── */
  .f4-use-case-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(min(100%,460px),1fr));
    gap: 2rem;
    margin-top: 2.5rem;
  }
  .f4-use-card {
    border: 1.5px solid var(--border-color);
    border-radius: 16px;
    overflow: hidden;
    background: var(--bg-primary);
    transition: transform .3s, box-shadow .3s;
    box-shadow: var(--shadow-sm);
  }
  .f4-use-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); }
  .f4-use-card-header {
    padding: 1.4rem 1.8rem;
    display: flex;
    align-items: center;
    gap: .8rem;
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--text-primary);
  }
  .f4-use-card-header .f4-emoji { font-size: 1.6rem; }
  .f4-use-card.f4-motorsport .f4-use-card-header { background: var(--accent-orange-light); border-bottom: 2px solid rgba(196,75,20,.25); }
  .f4-use-card.f4-daily .f4-use-card-header { background: var(--accent-blue-light); border-bottom: 2px solid rgba(29,78,216,.2); }
  .f4-use-card-body { padding: 1.4rem 1.8rem; }
  .f4-use-card-body p { font-size: .93rem; color: var(--text-secondary); line-height: 2; }
  .f4-use-card-body ul { list-style: none; margin-top: .8rem; display: flex; flex-direction: column; gap: .45rem; }
  .f4-use-card-body li { padding-right: 1.2rem; position: relative; font-size: .9rem; color: var(--text-secondary); line-height: 1.8; }
  .f4-use-card-body li strong { color: var(--text-primary); }
  .f4-use-card-body li::before {
    content: '◆';
    position: absolute;
    right: 0;
    font-size: .55rem;
    top: .55rem;
  }
  .f4-use-card.f4-daily li::before { color: var(--accent-blue); }
  .f4-use-card.f4-motorsport li::before { color: var(--accent-orange); }

  /* ── Divider ── */
  .f4-divider {
    height: 1px;
    background: var(--border-color);
    margin: 0;
  }

  /* ── Sub-headings ── */
  .f4-sub-heading {
    margin-top: 2rem;
    font-size: 1.15rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: .5rem;
  }
  .f4-sub-heading.f4-blue { color: var(--accent-blue); }
  .f4-sub-heading.f4-orange { color: var(--accent-orange); }
  .f4-sub-heading .f4-dot {
    width: 10px;
    height: 10px;
    border-radius: 3px;
    display: inline-block;
  }
  .f4-sub-heading.f4-blue .f4-dot { background: var(--accent-blue); }
  .f4-sub-heading.f4-orange .f4-dot { background: var(--accent-orange); }

  /* ── Animations ── */
  @keyframes f4FadeDown {
    from { opacity: 0; transform: translateY(-18px); }
    to { opacity: 1; transform: translateY(0); }
  }
  @keyframes f4Bounce {
    0%,100% { transform: translateX(-50%) translateY(0); }
    50% { transform: translateX(-50%) translateY(8px); }
  }

  /* ── Responsive ── */
  @media (max-width: 768px) {
    .f4-hero { min-height: 70vh; }
    .f4-wrap section { padding: 3.5rem 0; }
    .f4-diagram-card, .f4-pro-con-card, .f4-use-card-body, .f4-use-card-header { padding: 1.3rem; }
    .f4-comp-grid { grid-template-columns: 1fr; }
    .f4-wrap thead th, .f4-wrap tbody td { padding: .7rem .8rem; font-size: .85rem; }
  }
  @media (max-width: 480px) {
    .f4-hero { min-height: 60vh; padding: 1.2rem; }
    .f4-container { padding: 0 1rem; }
  }