:root {
        --bg-deep: #0b1422;
        --bg-panel: #101b2e;
        --bg-card: #0f1a2b;
        --bg-pill: #1b2739;
        --accent: #f5a000;
        --accent-soft: #f6b43a;
        --text: #e8eef7;
        --muted: #9aa9bf;
        --muted-2: #7d8aa1;
        --blue: #13508f;
        --blue-2: #0f3f73;
        --border: rgba(255, 255, 255, 0.08);
        --glow: rgba(245, 160, 0, 0.2);
        --shadow: 0 18px 40px rgba(5, 10, 20, 0.55);
        --radius-xl: 22px;
        --radius-lg: 16px;
        --radius-md: 12px;
        --radius-sm: 10px;
      }

      * {
        box-sizing: border-box;
      }

      body {
        margin: 0;
        font-family: "Urbanist", "Poppins", "Segoe UI", sans-serif;
 /*       background: linear-gradient(180deg, #0a1424 0%, #0d1a2d 22%, #0f2b52 55%, #114a87 100%);*/
        color: var(--text);
      }

      img {
        max-width: 100%;
        display: block;
      }

      a {
        color: inherit;
        text-decoration: none;
      }

      .page {
        max-width: 1100px;
        margin: 0 auto;
        padding: 0 20px 80px;
      }

      .topbar {
        display: flex;
        align-items: center;
        justify-content: space-between;
        padding: 16px 0;
        border-bottom: 1px solid var(--border);
        position: sticky;
        top: 0;
        background: rgba(11, 20, 34, 0.92);
        backdrop-filter: blur(12px);
        z-index: 10;
      }

      .brand {
        display: flex;
        align-items: center;
        gap: 10px;
        font-weight: 700;
        letter-spacing: 0.5px;
      }

      .brand .logo {
        width: 28px;
        height: 28px;
        border-radius: 8px;
        background: linear-gradient(135deg, #1f2b3d, #101b2e);
        border: 1px solid var(--border);
        display: grid;
        place-items: center;
      }

      .brand span {
        color: var(--accent);
      }

      .hero1 {
        padding: 28px 0 40px;
      }

      .hero1-card {
        background: radial-gradient(circle at top right, rgba(245, 160, 0, 0.25), transparent 45%),
          linear-gradient(180deg, #101b2e 0%, #0c1626 100%);
        border-radius: var(--radius-xl);
        padding: 32px 28px;
        box-shadow: var(--shadow);
        border: 1px solid var(--border);
      }

      .badge {
        display: inline-flex;
        align-items: center;
        gap: 8px;
        background: rgba(245, 160, 0, 0.12);
        color: var(--accent);
        padding: 6px 12px;
        border-radius: 999px;
        font-size: 12px;
        text-transform: uppercase;
        letter-spacing: 1px;
      }

      .hero1 h1 {
        font-size: 40px;
        margin: 16px 0 8px;
      }

      .hero1 p {
        color: var(--muted);
        margin: 0 0 18px;
      }

      .hero-actions {
        display: flex;
        gap: 12px;
        flex-wrap: wrap;
      }

      .btn {
        padding: 12px 18px;
        border-radius: 12px;
        border: 1px solid transparent;
        font-weight: 600;
        cursor: pointer;
      }

      .btn-primary {
        background: var(--accent);
        color: #1a1206;
      }

      .btn-secondary {
        background: #1b2739;
        color: var(--text);
        border-color: var(--border);
      }

      .section {
        margin-top: 36px;
      }

      .section-title {
        font-size: 28px;
        margin: 0 0 6px;
      }

      .section-subtitle {
        color: var(--muted);
        margin: 0 0 18px;
      }

      .grid-2 {
        display: grid;
        gap: 16px;
        grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
      }

      .feature-card {
        background: var(--bg-card);
        border-radius: var(--radius-lg);
        padding: 18px;
        border: 1px solid var(--border);
        box-shadow: var(--shadow);
      }

      .feature-card h4 {
        margin: 8px 0 6px;
      }

      .feature-card p {
        color: var(--muted);
        margin: 0;
        font-size: 14px;
      }

      .tools {
        background: var(--blue);
        padding: 28px;
        border-radius: var(--radius-xl);
        box-shadow: var(--shadow);
        border: 1px solid rgba(255, 255, 255, 0.08);
      }

      .tool-card {
        background: linear-gradient(180deg, #0f1a2b 0%, #0b1526 100%);
        border-radius: var(--radius-xl);
        padding: 20px;
        margin-top: 16px;
        border: 1px solid var(--border);
        box-shadow: var(--shadow);
      }

      .tool-head {
        display: flex;
        align-items: center;
        gap: 10px;
        font-weight: 700;
        font-size: 18px;
        margin-bottom: 14px;
      }

      .pill-row {
        display: flex;
        gap: 10px;
        flex-wrap: wrap;
        margin-bottom: 16px;
      }

      .pill {
        padding: 8px 14px;
        border-radius: 999px;
        background: var(--bg-pill);
        color: var(--text);
        border: 1px solid var(--border);
        cursor: pointer;
        font-size: 14px;
      }

      .pill.active {
        background: var(--accent);
        color: #1a1206;
        border-color: transparent;
      }

      .field {
        display: grid;
        gap: 10px;
        margin-bottom: 14px;
      }

      label {
        font-size: 13px;
        color: var(--muted);
      }

      input,
      select {
        padding: 12px 14px;
        border-radius: 10px;
        border: 1px solid var(--border);
        background: #1a2434;
        color: var(--text);
        font-size: 16px;
      }

      .result-card {
        padding: 16px;
        border-radius: 14px;
        background: rgba(245, 160, 0, 0.08);
        border: 1px solid rgba(245, 160, 0, 0.35);
        text-align: center;
        margin-top: 10px;
      }

      .result-card strong {
        font-size: 32px;
        color: var(--accent);
        display: block;
        margin: 6px 0;
      }

      .result-card small {
        color: var(--muted-2);
      }

      .two-col {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
        gap: 12px;
      }

      .equations {
        background: var(--blue);
        padding: 28px;
        border-radius: var(--radius-xl);
        box-shadow: var(--shadow);
        border: 1px solid rgba(255, 255, 255, 0.08);
      }

      .accordion {
        background: var(--bg-card);
        border-radius: var(--radius-lg);
        padding: 16px;
        border: 1px solid var(--border);
        margin-top: 12px;
      }

      .accordion-header {
        display: flex;
        justify-content: space-between;
        align-items: center;
        cursor: pointer;
        gap: 10px;
      }

      .accordion-title {
        font-weight: 600;
      }

      .accordion-body {
        margin-top: 12px;
        color: var(--muted);
        display: none;
      }

      .accordion.open .accordion-body {
        display: block;
      }

      .library {
        background: var(--blue);
        padding: 28px;
        border-radius: var(--radius-xl);
        border: 1px solid rgba(255, 255, 255, 0.08);
        box-shadow: var(--shadow);
      }

      .search {
        display: flex;
        gap: 10px;
        align-items: center;
        background: #1a2434;
        border-radius: 12px;
        padding: 10px 14px;
        border: 1px solid var(--border);
      }

      .search input {
        border: none;
        background: transparent;
        flex: 1;
        padding: 4px 0;
      }

      .library-card {
        background: var(--bg-card);
        border-radius: var(--radius-lg);
        padding: 16px;
        margin-top: 12px;
        border: 1px solid var(--border);
        display: grid;
        gap: 8px;
      }

      .library-card span {
        color: var(--accent);
        font-size: 12px;
        text-transform: uppercase;
        letter-spacing: 1px;
      }

      .library-card h4 {
        margin: 0;
      }

      .library-card p {
        margin: 0;
        color: var(--muted);
        font-size: 14px;
      }

      .notes {
        background: var(--blue);
        padding: 28px;
        border-radius: var(--radius-xl);
        border: 1px solid rgba(255, 255, 255, 0.08);
        box-shadow: var(--shadow);
      }

      .note-list {
        background: var(--bg-card);
        border-radius: var(--radius-lg);
        padding: 16px;
        border: 1px solid var(--border);
      }

      .note-item {
        padding: 12px;
        border-radius: 12px;
        margin-bottom: 10px;
        background: transparent;
        color: var(--muted);
        display: flex;
        align-items: center;
        gap: 10px;
      }

      .note-item.active {
        background: rgba(245, 160, 0, 0.16);
        color: var(--accent);
      }

      .note-card {
        background: var(--bg-card);
        border-radius: var(--radius-lg);
        padding: 16px;
        border: 1px solid var(--border);
        margin-top: 16px;
      }

      .note-card h4 {
        margin: 0 0 10px;
      }

      .note-card p {
        color: var(--muted);
        margin: 0;
        line-height: 1.5;
      }

      footer {
        margin-top: 40px;
        text-align: center;
        color: var(--muted);
        font-size: 12px;
      }

      @media (max-width: 720px) {
        .hero1 h1 {
          font-size: 32px;
        }
      }