* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    font-family: 'Poppins', Arial, sans-serif;
    line-height: 1.7;
    color: #111827;
    background: linear-gradient(135deg, #e9ecef, #d3e0ff);
}
header {
    background: #0a2463;
    color: #fff;
    padding: 0.8rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 4px 8px rgba(0,0,0,0.15);
}
header .container {
    max-width: 1300px;
    margin: auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 30px;
}
header h1 {
    font-size: 1.8rem;
    font-weight: 600;
}
header nav ul {
    list-style: none;
    display: flex;
    gap: 20px;
}
header nav a {
    color: #0a2463; /* Dark blue for header nav links */
    text-decoration: none;
    font-weight: 500;
    font-size: 0.9rem;
    transition: color 0.3s ease;
}
header nav a:hover {
    color: #0a2463; /* Dark blue on hover for header nav links */
}
.container {
    max-width: 1300px;
    margin: 40px auto;
    padding: 40px;
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 0 25px rgba(0,0,0,0.1);
}
.calculator-section {
    margin-bottom: 50px;
    padding: 30px;
    background: #f8fafc;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.08);
}
.calculator {
    background: #1f2937;
    padding: 25px;
    border-radius: 12px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.2);
    width: 360px;
    margin: 0 auto;
}
#display {
    width: 100%;
    height: 60px;
    background: #fff;
    color: #111827;
    border: none;
    border-radius: 8px;
    padding: 15px;
    font-size: 24px;
    text-align: right;
    margin-bottom: 15px;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
}
.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
}
button {
    padding: 18px;
    font-size: 18px;
    border: none;
    border-radius: 8px;
    background: #0284c7;
    color: #fff;
    cursor: pointer;
    transition: background 0.3s ease, transform 0.1s ease;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}
button:hover {
    background: #026395;
    transform: translateY(-2px);
}
.operator {
    background: #d97706;
}
.operator:hover {
    background: #b35900;
}
.clear {
    background: #dc2626;
}
.clear:hover {
    background: #b91c1c;
}
.equals {
    background: #059669;
}
.equals:hover {
    background: #047857;
}
h1, h2, h3 {
    color: #0a2463;
}
h1 {
    font-size: 3rem;
    margin-bottom: 30px;
    font-weight: 700;
}
h2 {
    font-size: 2.2rem;
    margin: 30px 0 15px;
    font-weight: 600;
}
h3 {
    font-size: 1.6rem;
    margin: 25px 0 12px;
    font-weight: 500;
}
p {
    margin-bottom: 20px;
    font-size: 1.1rem;
}
a {
    color: #0284c7;
    text-decoration: none;
    transition: color 0.3s ease;
}
a:hover {
    color: #00c4b4;
}
ul {
    margin-bottom: 20px;
    padding-left: 30px;
}
table {
    width: 100%;
    border-collapse: collapse;
    margin: 30px 0;
}
th, td {
    border: 1px solid #e2e8f0;
    padding: 15px;
    text-align: left;
    color: #111827;
}
th {
    background: #f1f5f9;
    font-weight: 600;
}
footer {
    background: #0a2463;
    color: #e9ecef;
    padding: 3rem 0;
}
footer .container {
    max-width: 1300px;
    margin: auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 40px;
    padding: 0 40px;
}
footer .footer-section a {
    color: #0a2463; /* Dark blue for Quick Links, Legal, and Company */
    transition: color 0.3s ease;
}
footer .footer-section a:hover {
    color: #0a2463; /* Dark blue on hover */
}
footer .contact-section a {
    color: #b8d0eb; /* Lighter color for Contact section links */
    transition: color 0.3s ease;
}
footer .contact-section a:hover {
    color: #00c4b4; /* Teal on hover for Contact section */
}
footer .footer-section {
    min-width: 200px;
}
footer h3 {
    color: #fff;
    margin-bottom: 15px;
    font-size: 1.4rem;
    font-weight: 600;
}
footer ul {
    list-style: none;
    padding: 0;
}
footer ul li {
    margin-bottom: 12px;
}
footer p {
    color: #e9ecef;
}
.back-to-top {
    position: fixed;
    bottom: 40px;
    right: 40px;
    background: #0284c7;
    color: #fff;
    padding: 12px 20px;
    border-radius: 8px;
    text-decoration: none;
    display: none;
    font-size: 1rem;
    font-weight: 500;
    transition: background 0.3s ease;
}
.back-to-top:hover {
    background: #00c4b4;
}
/* Hamburger Menu for Mobile */
.hamburger {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: #0a2463; /* Dark blue for hamburger icon */
}
.nav-menu {
    display: flex;
}
@media (max-width: 768px) {
    header .container {
        flex-direction: column;
        padding: 0 15px;
    }
    header h1 {
        font-size: 1.5rem;
        margin-bottom: 10px;
    }
    .hamburger {
        display: block;
    }
    .nav-menu {
        display: none;
        flex-direction: column;
        width: 100%;
        background: #0a2463;
        position: absolute;
        top: 100%;
        left: 0;
        padding: 15px;
    }
    .nav-menu.active {
        display: flex;
    }
    header nav ul {
        flex-direction: column;
        gap: 12px;
    }
    .container {
        padding: 20px;
    }
    .calculator {
        width: 100%;
    }
    h1 {
        font-size: 2.4rem;
    }
    h2 {
        font-size: 1.8rem;
    }
    .buttons button {
        padding: 15px;
        font-size: 16px;
    }
    footer .container {
        grid-template-columns: 1fr;
        text-align: center;
    }
}