* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

body {
    background: #000;
    color: #fff;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    padding: 1.5rem 2rem;
    display: flex;
    justify-content: flex-end;
}

header a {
    color: #fff;
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 500;
}

header a:hover {
    text-decoration: underline;
}

main {
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
    padding: 2rem;
}

.hero {
    text-align: center;
    margin-bottom: 6rem;
}

.hero h1 {
    font-size: clamp(4rem, 15vw, 10rem);
    font-weight: 900;
    letter-spacing: -0.04em;
    line-height: 0.9;
    margin-bottom: 1rem;
}

.tagline {
    font-size: clamp(1.5rem, 4vw, 2.5rem);
    color: #999;
    margin-bottom: 2rem;
}

.features {
    list-style: none;
    margin-bottom: 2rem;
}

.features li {
    font-size: 1.25rem;
    color: #999;
    line-height: 1.8;
}

.desc {
    font-size: 1rem;
    color: #888;
    line-height: 1.6;
    margin-bottom: 2.5rem;
}

.btn {
    display: inline-block;
    background: #fff;
    color: #000;
    padding: 0.75rem 1.5rem;
    text-decoration: none;
    font-weight: 400;
    font-size: 0.8125rem;
    border-radius: 50px;
}

.btn:hover {
    background: #e0e0e0;
}

.faq {
    max-width: 500px;
    margin: 0 auto;
    width: 100%;
}

.faq h2 {
    font-size: 0.75rem;
    font-weight: 500;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: #888;
    margin-bottom: 1.5rem;
    text-align: center;
}

details {
    border-top: 1px solid #222;
    padding: 1rem 0;
}

details:last-of-type {
    border-bottom: 1px solid #222;
}

summary {
    cursor: pointer;
    font-weight: 500;
    font-size: 0.9375rem;
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

summary::-webkit-details-marker {
    display: none;
}

summary::after {
    content: '+';
    font-weight: 300;
    font-size: 1.25rem;
    color: #666;
}

details[open] summary::after {
    content: '−';
}

details p {
    margin-top: 0.75rem;
    color: #999;
    font-size: 0.875rem;
    line-height: 1.5;
}

footer {
    padding: 2rem;
    text-align: center;
    border-top: 1px solid #222;
}

.footer-links {
    margin-bottom: 1rem;
}

.footer-links a {
    color: #666;
    text-decoration: none;
    font-size: 0.75rem;
    margin: 0 1rem;
}

.footer-links a:hover {
    color: #fff;
}

footer p {
    color: #444;
    font-size: 0.75rem;
}

.page-content {
    max-width: 600px;
    margin: 0 auto;
    width: 100%;
}

.page-content h1 {
    font-size: clamp(2rem, 8vw, 4rem);
    font-weight: 900;
    letter-spacing: -0.04em;
    line-height: 0.9;
    margin-bottom: 2rem;
    text-align: center;
}

.page-content h2 {
    font-size: 1rem;
    font-weight: 600;
    margin: 2rem 0 0.75rem;
}

.page-content p {
    font-size: 0.9375rem;
    color: #999;
    line-height: 1.7;
    margin-bottom: 1rem;
}

.page-content ul {
    margin: 0 0 1rem 1.5rem;
    color: #999;
    font-size: 0.9375rem;
    line-height: 1.7;
}

.page-content a {
    color: #fff;
}

.calculator {
    max-width: 400px;
    margin: 0 auto 3rem;
    width: 100%;
}

.calculator label {
    display: block;
    font-size: 0.75rem;
    font-weight: 500;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: #999;
    margin-bottom: 0.5rem;
}

.calculator input,
.calculator select {
    width: 100%;
    padding: 0.75rem 1rem;
    font-size: 1rem;
    border: 1px solid #333;
    background: #111;
    color: #fff;
    margin-bottom: 1rem;
    font-family: inherit;
}

.calculator input:focus,
.calculator select:focus {
    outline: none;
    border-color: #fff;
}

.calculator .btn {
    width: 100%;
    border: none;
    cursor: pointer;
    margin-top: 0.5rem;
}

.result {
    text-align: center;
    margin-top: 2rem;
    padding: 2rem;
    border: 1px solid #333;
}

.result-value {
    font-size: 3rem;
    font-weight: 900;
    letter-spacing: -0.04em;
}

.result-label {
    font-size: 0.75rem;
    color: #666;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-top: 0.5rem;
}

.contact-form {
    max-width: 400px;
    margin: 0 auto;
    width: 100%;
}

.contact-form label {
    display: block;
    font-size: 0.75rem;
    font-weight: 500;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: #999;
    margin-bottom: 0.5rem;
}

.contact-form input,
.contact-form textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    font-size: 1rem;
    border: 1px solid #333;
    background: #111;
    color: #fff;
    margin-bottom: 1rem;
    font-family: inherit;
}

.contact-form textarea {
    min-height: 150px;
    resize: vertical;
}

.contact-form input:focus,
.contact-form textarea:focus {
    outline: none;
    border-color: #fff;
}

.contact-form .btn {
    width: 100%;
    border: none;
    cursor: pointer;
}

.download-prompt {
    display: inline-block;
    margin-top: 1.5rem;
    color: #fff;
    text-decoration: underline;
    font-size: 0.875rem;
    animation: bounce 1s ease infinite;
}

@keyframes bounce {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-6px);
    }
}

.formula-list {
    margin: 1.5rem 0 3rem;
}

.formula-item {
    border-top: 1px solid #222;
    padding: 1rem 0;
}

.formula-item:last-child {
    border-bottom: 1px solid #222;
}

.formula-item strong {
    display: block;
    margin-bottom: 0.25rem;
}

.formula-item span {
    color: #888;
    font-size: 0.875rem;
}

@media (max-width: 600px) {
    .hero h1 {
        font-size: clamp(3rem, 20vw, 5rem);
    }
    
    .features li {
        font-size: 1rem;
    }
    
    .desc {
        font-size: 0.875rem;
    }
    
    main {
        padding: 1.5rem;
    }
    
    .footer-links a {
        display: block;
        margin: 0.5rem 0;
    }
}