:root {
    --bg: #F5F5F0;
    --dark: #0D0D0D;
    --gray: #222222;
    --accent: #C8FF00;
}

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

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background-color: var(--bg);
    color: var(--dark);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.container {
    width: 90%;
    max-width: 500px;
    margin: 40px auto;
}

header { padding: 20px 0; border-bottom: 1px solid rgba(13, 13, 13, 0.1); }
.logo { font-size: 1.5rem; font-weight: 900; letter-spacing: -1px; }

h1 { font-size: 2rem; font-weight: 800; line-height: 1.1; margin: 20px 0; }

.card {
    background: #FFFFFF;
    border: 2px solid var(--dark);
    padding: 25px;
    margin-top: 20px;
    box-shadow: 6px 6px 0px var(--dark); /* Design Neo-brutalista */
}

.input-group { margin-bottom: 20px; }
label { display: block; font-size: 0.85rem; font-weight: 700; text-transform: uppercase; margin-bottom: 8px; }

input {
    width: 100%;
    padding: 15px;
    border: 2px solid var(--dark);
    font-size: 1rem;
    font-weight: 600;
    outline: none;
}

input:focus { background-color: #fff; border-color: var(--gray); }

.btn-main {
    width: 100%;
    padding: 18px;
    background-color: var(--accent);
    color: var(--dark);
    border: 2px solid var(--dark);
    font-weight: 900;
    font-size: 1rem;
    text-transform: uppercase;
    cursor: pointer;
    transition: 0.2s ease;
}

.btn-main:hover { transform: translate(-2px, -2px); box-shadow: 4px 4px 0px var(--dark); }
.btn-main:active { transform: translate(0, 0); box-shadow: 0px 0px 0px var(--dark); }

.result-area {
    display: none;
    margin-top: 30px;
    padding: 20px;
    background: var(--dark);
    color: #fff;
    border: 2px solid var(--dark);
}

.result-area strong { color: var(--accent); font-size: 1.4rem; }

/* Mobile First */
@media (max-width: 480px) {
    h1 { font-size: 1.6rem; }
    .card { padding: 20px; }
}