:root {
        --primary: #4285f4;
        --secondary: #34a853;
        --dark: #202124;
        --light: #f8f9fa;
        --danger: #ea4335;
    }

    * {
        box-sizing: border-box;
        margin: 0;
        padding: 0;
        font-family: 'Roboto', Arial, sans-serif;
    }

    body {
        background-color: var(--light);
        color: var(--dark);
        padding: 0;
    }

    /* Header */
    .site-header {
        background-color: #4361ee;
        color: white;
        display: flex;
        justify-content: space-between;
        align-items: center;
        padding: 5px 20px;
    }

    .logo {
        display: flex;
        align-items: center;
    }

    .logo img {
        height: 40px;
        margin-right: 10px;
        object-fit: cover;
        position: relative;
        top: 2px;
        filter: drop-shadow(0 0 3px rgb(255, 255, 255));
    }

    .logo a span {
        font-family: 'Poppins', sans-serif;
        font-size: 1.5rem;
        font-weight: bolder;
        background: linear-gradient(to right, #aa00ff, #0015ff, #1b9400, #ffae00, #ff0000, #ffae00, #1b9400, #0015ff, #aa00ff);
        background-size: 200%;
        background-clip: text;
        -webkit-background-clip: text;
        -webkit-text-fill-color: transparent;
        animation: animate-gradient 2.5s linear infinite;
    }

    @keyframes animate-gradient {
        to {
            background-position: 200%;
        }
    }

    .logo a {
        text-decoration: none;
        color: white;
    }

    .nav-links a {
        color: white;
        text-decoration: none;
        margin-left: 20px;
        font-size: 1rem;
        font-weight: bold;
    }

    .nav-links a:hover {
        text-decoration: underline;
        color: aqua;
    }

    /* Calculator */
    .calculator {
        width: 100%;
        max-width: 400px;
        margin: 40px auto 20px;
        background: white;
        border-radius: 12px;
        box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
        overflow: hidden;
    }

    .header {
        background-color: var(--primary);
        color: white;
        padding: 15px;
        text-align: center;
        font-size: 1.5rem;
        font-weight: 500;
    }

    .display {
        padding: 20px;
        background-color: #f1f3f4;
        text-align: right;
    }

    .previous-operand {
        font-size: 1rem;
        color: #5f6368;
        height: 20px;
        margin-bottom: 8px;
    }

    .current-operand {
        font-size: 2rem;
        font-weight: 500;
    }

    .buttons {
        display: grid;
        grid-template-columns: repeat(4, 1fr);
        gap: 1px;
        background-color: #dadce0;
    }

    button {
        border: none;
        padding: 20px;
        font-size: 1.2rem;
        background-color: white;
        cursor: pointer;
        transition: all 0.2s;
    }

    button:hover {
        background-color: #f1f3f4;
    }

    .span-2 {
        grid-column: span 2;
    }

    .operation-btn {
        background-color: #e8f0fe;
        color: var(--primary);
    }

    .equals-btn {
        background-color: var(--secondary);
        color: white;
    }

    .clear-btn {
        background-color: var(--danger);
        color: white;
    }

    .binary-btn {
        font-weight: bold;
    }

    /* SEO Section */
    .seo-content {
        max-width: 800px;
        margin: 40px auto;
        padding: 20px;
        padding-left: 30px;
        background: #fff;
        border-radius: 8px;
        line-height: 1.7;
    }

    .seo-content h2,
    .seo-content h3 {
        margin-top: 20px;
        color: var(--primary);
    }

    /* Footer */
    footer {
        text-align: center;
        padding: 15px;
        background-color: #202124;
        color: #f1f1f1;
        font-size: small;
    }

    footer a {
        text-decoration: none;
        color: #aa00ff;
        font-weight: bold;
    }

    footer a:hover {
        color: aqua;
    }

    @media (min-width: 300px) and (max-width:350px) {
        .nav-links a {
            font-size: small;
            margin: 0 0 0 10px;
        }

        .site-header {
            padding: 5px 10px;
        }
    }