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

:root {
    --bg: #08090d;
    --bg-soft: #101218;
    --card: #14161d;
    --card-hover: #1a1d26;

    --text: #f5f5f7;
    --muted: #9296a3;

    --accent: #8b5cf6;
    --accent-2: #a78bfa;

    --green: #22c55e;
    --red: #ef4444;

    --border: #252832;
}

body {
    background: var(--bg);
    color: var(--text);
    font-family: Inter, Arial, sans-serif;
    line-height: 1.6;
}

.container {
    width: min(1100px, 92%);
    margin: auto;
}


/* HEADER */

.header {
    border-bottom: 1px solid var(--border);
    background: rgba(8, 9, 13, .9);
}

.nav {
    height: 70px;

    display: flex;
    align-items: center;
    justify-content: space-between;
}

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

    font-size: 22px;
    font-weight: 800;
}

.logo span {
    color: var(--accent-2);
}

.back-btn {
    color: var(--muted);
    text-decoration: none;
}

.back-btn:hover {
    color: white;
}


/* HERO */

.hero {
    text-align: center;

    padding: 70px 20px 40px;
}

.badge {
    display: inline-block;

    padding: 6px 12px;

    border-radius: 999px;

    background: rgba(139, 92, 246, .12);

    color: var(--accent-2);

    font-size: 13px;
    font-weight: 600;

    margin-bottom: 15px;
}

.hero h1 {
    font-size: clamp(36px, 6vw, 60px);

    line-height: 1.1;

    margin-bottom: 18px;
}

.hero p {
    max-width: 700px;

    margin: auto;

    color: var(--muted);

    font-size: 17px;
}


/* SOLVER */

.solver-card {
    background: var(--card);

    border: 1px solid var(--border);

    border-radius: 18px;

    padding: 30px;

    box-shadow:
        0 20px 60px rgba(0, 0, 0, .25);
}

.section-header {
    display: flex;

    align-items: center;
    justify-content: space-between;

    gap: 20px;

    margin-bottom: 25px;
}

.section-header h2 {
    font-size: 22px;
}

.section-header p {
    color: var(--muted);
    font-size: 14px;
}

.example-btn {
    background: transparent;

    color: var(--accent-2);

    border: 1px solid var(--border);

    padding: 10px 16px;

    border-radius: 9px;

    cursor: pointer;
}

.example-btn:hover {
    background: var(--card-hover);
}


/* INPUT */

.input-group label {
    display: block;

    margin-bottom: 8px;

    font-weight: 600;
}

textarea {
    width: 100%;

    min-height: 180px;

    resize: vertical;

    background: var(--bg-soft);

    border: 1px solid var(--border);

    border-radius: 12px;

    color: var(--text);

    padding: 18px;

    font-family: "Courier New", monospace;

    font-size: 15px;

    outline: none;
}

textarea:focus {
    border-color: var(--accent);
}


/* OPTIONS */

.options {
    display: flex;

    gap: 20px;

    margin-top: 20px;
}

.option {
    flex: 1;
}

.option label {
    display: block;

    font-size: 13px;

    color: var(--muted);

    margin-bottom: 7px;
}

.option input {
    width: 100%;

    padding: 12px;

    background: var(--bg-soft);

    border: 1px solid var(--border);

    border-radius: 9px;

    color: white;

    outline: none;
}


/* BUTTON */

.solve-btn {
    width: 100%;

    margin-top: 25px;

    padding: 15px;

    border: none;

    border-radius: 10px;

    background: var(--accent);

    color: white;

    font-size: 16px;

    font-weight: 700;

    cursor: pointer;

    transition: .2s;
}

.solve-btn:hover {
    background: var(--accent-2);

    transform: translateY(-1px);
}


/* ERROR */

.error {
    margin-top: 20px;

    padding: 15px;

    border-radius: 10px;

    background: rgba(239, 68, 68, .1);

    border: 1px solid rgba(239, 68, 68, .3);

    color: #fca5a5;
}


/* LOADING */

.loading {
    display: flex;

    justify-content: center;
    align-items: center;

    gap: 12px;

    padding: 30px;

    color: var(--muted);
}

.spinner {
    width: 20px;
    height: 20px;

    border: 3px solid var(--border);

    border-top-color: var(--accent);

    border-radius: 50%;

    animation: spin .8s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}


/* RESULTS */

.result {
    margin-top: 30px;

    border-top: 1px solid var(--border);

    padding-top: 25px;
}

.result-header h2 {
    font-size: 22px;
}

.result-header p {
    color: var(--muted);

    font-size: 14px;
}

.solution {
    background: var(--bg-soft);

    border: 1px solid var(--border);

    border-radius: 12px;

    padding: 18px;

    margin-top: 15px;
}

.solution-title {
    color: var(--accent-2);

    font-size: 13px;

    margin-bottom: 10px;
}

.variable {
    display: flex;

    justify-content: space-between;

    gap: 20px;

    padding: 8px 0;

    border-bottom: 1px solid rgba(255,255,255,.04);
}

.variable:last-child {
    border-bottom: none;
}

.variable-name {
    font-weight: 700;
}

.variable-value {
    font-family: "Courier New", monospace;

    color: var(--green);
}


/* METHOD */

.method-box {
    margin-top: 20px;

    padding: 15px;

    border-radius: 10px;

    background: rgba(139, 92, 246, .07);

    border: 1px solid rgba(139, 92, 246, .15);
}

.method-box p {
    margin-top: 5px;

    color: var(--muted);

    font-size: 14px;
}


/* ITERATIONS */

.iterations-box {
    margin-top: 25px;

    border-top: 1px solid var(--border);

    padding-top: 25px;
}

.iteration {
    padding: 10px 0;

    border-bottom: 1px solid var(--border);

    font-family: monospace;

    font-size: 13px;

    color: var(--muted);
}


/* INFO */

.info-grid {
    display: grid;

    grid-template-columns:
        repeat(3, 1fr);

    gap: 20px;

    margin: 30px 0;
}

.info-card {
    background: var(--card);

    border: 1px solid var(--border);

    border-radius: 14px;

    padding: 22px;
}

.info-card h3 {
    margin-bottom: 8px;
}

.info-card p {
    color: var(--muted);

    font-size: 14px;
}


/* SEO */

.seo-content {
    margin: 60px 0;

    color: var(--muted);
}

.seo-content h2,
.seo-content h3 {
    color: white;

    margin-bottom: 12px;
}

.seo-content h3 {
    margin-top: 25px;
}

.seo-content ul {
    margin-left: 20px;
}

.seo-content pre {
    background: var(--card);

    border: 1px solid var(--border);

    border-radius: 10px;

    padding: 20px;

    overflow-x: auto;

    color: var(--accent-2);
}


/* FOOTER */

footer {
    border-top: 1px solid var(--border);

    padding: 30px 0;

    color: var(--muted);

    font-size: 13px;
}


/* UTIL */

.hidden {
    display: none !important;
}


/* MOBILE */

@media (max-width: 700px) {

    .solver-card {
        padding: 20px;
    }

    .section-header {
        align-items: flex-start;

        flex-direction: column;
    }

    .options {
        flex-direction: column;
    }

    .info-grid {
        grid-template-columns: 1fr;
    }

    .variable {
        flex-direction: column;

        gap: 2px;
    }

}