:root {
    --bg: #0b1220;
    --bg-soft: #10192b;
    --panel: #121d31;
    --panel-2: #17243d;
    --text: #edf4ff;
    --muted: #9fb0cb;
    --line: rgba(255,255,255,0.09);
    --accent: #4cc4ff;
    --accent-2: #7b8cff;
    --accent-3: #00d2b8;
    --danger: #ff7d7d;
    --warn: #ffd166;
    --ok: #52d273;
    --shadow: 0 24px 70px rgba(0, 0, 0, 0.28);
    --radius: 24px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
    margin: 0;
    color: var(--text);
    font-family: Arial, Helvetica, sans-serif;
    background:
        radial-gradient(circle at top left, rgba(76,196,255,0.12), transparent 28%),
        radial-gradient(circle at top right, rgba(123,140,255,0.12), transparent 24%),
        linear-gradient(180deg, #08101d 0%, #0b1220 100%);
}

img {
    display: block;
    max-width: 100%;
}

.page-shell {
    width: min(1240px, calc(100% - 28px));
    margin: 0 auto;
    padding: 28px 0 50px;
}

.hero {
    display: grid;
    grid-template-columns: minmax(0, 1.6fr) minmax(260px, .8fr);
    gap: 22px;
    margin-bottom: 24px;
}

.hero-copy,
.hero-panel {
    background: linear-gradient(180deg, rgba(18,29,49,0.92), rgba(14,24,40,0.95));
    border: 1px solid var(--line);
    border-radius: calc(var(--radius) + 4px);
    box-shadow: var(--shadow);
}

.hero-copy {
    padding: 34px;
}

.hero-panel {
    padding: 24px;
    display: grid;
    gap: 16px;
    align-content: center;
}

.eyebrow {
    margin: 0 0 10px;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: .12em;
    font-size: 12px;
    font-weight: 700;
}

.hero h1 {
    margin: 0;
    font-size: clamp(2rem, 3vw, 3.3rem);
    line-height: 1.05;
}

.lead {
    margin: 16px 0 0;
    color: var(--muted);
    line-height: 1.7;
    max-width: 850px;
}

.hero-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 20px;
}

.hero-tags span,
.hero-stat {
    border: 1px solid rgba(255,255,255,0.08);
    background: rgba(255,255,255,0.03);
    border-radius: 999px;
}

.hero-tags span {
    padding: 10px 14px;
    color: #d7e7ff;
    font-size: 14px;
}

.hero-stat {
    padding: 16px 18px;
    border-radius: 18px;
}

.hero-stat strong {
    display: block;
    margin-bottom: 8px;
    font-size: 1rem;
}

.hero-stat span {
    display: block;
    color: var(--muted);
    line-height: 1.5;
}

.layout {
    display: grid;
    grid-template-columns: repeat(12, 1fr);
    gap: 20px;
}

.card {
    background: linear-gradient(180deg, rgba(18,29,49,0.96), rgba(14,24,40,0.96));
    border: 1px solid var(--line);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 24px;
}

.card-form { grid-column: span 4; }
.card-visual { grid-column: span 8; }
.card-results { grid-column: span 8; }
.card-formulas { grid-column: span 4; }

.section-head h2 {
    margin: 0;
    font-size: 1.4rem;
}

.section-head p {
    margin: 8px 0 0;
    color: var(--muted);
    line-height: 1.6;
}

.form-grid {
    display: grid;
    gap: 16px;
    margin-top: 22px;
}

label span {
    display: block;
    margin-bottom: 8px;
    font-size: .95rem;
    font-weight: 700;
    color: #dfeaff;
}

input {
    width: 100%;
    padding: 15px 16px;
    border-radius: 16px;
    border: 1px solid rgba(255,255,255,0.12);
    background: rgba(255,255,255,0.04);
    color: var(--text);
    font-size: 1rem;
}

input::placeholder {
    color: #7f92af;
}

input:focus {
    outline: 3px solid rgba(76,196,255,0.18);
    border-color: rgba(76,196,255,0.48);
}

button {
    border: 0;
    cursor: pointer;
    padding: 15px 22px;
    border-radius: 16px;
    font-size: 1rem;
    font-weight: 700;
    color: #07111f;
    background: linear-gradient(135deg, var(--accent), var(--accent-3));
    box-shadow: 0 16px 30px rgba(0, 210, 184, 0.18);
}

button:hover {
    transform: translateY(-1px);
}

.alert {
    margin-top: 18px;
    padding: 16px 18px;
    border-radius: 18px;
}

.alert-error {
    border: 1px solid rgba(255,125,125,0.35);
    background: rgba(255,125,125,0.08);
}

.alert ul {
    margin: 10px 0 0 18px;
    padding: 0;
    color: #ffd7d7;
}

.info-boxes {
    display: grid;
    gap: 12px;
    margin-top: 18px;
}

.info-boxes article,
.formula-list article,
.result-item {
    border: 1px solid rgba(255,255,255,0.08);
    background: linear-gradient(180deg, rgba(255,255,255,0.04), rgba(255,255,255,0.02));
    border-radius: 18px;
}

.info-boxes article {
    padding: 16px;
}

.info-boxes strong {
    display: block;
    margin-bottom: 8px;
}

.info-boxes p {
    margin: 0;
    color: var(--muted);
    line-height: 1.6;
}

.illustration {
    margin: 22px 0 18px;
    padding: 16px;
    border-radius: 22px;
    background: linear-gradient(180deg, rgba(255,255,255,0.03), rgba(255,255,255,0.01));
    border: 1px solid rgba(255,255,255,0.08);
}

.illustration img {
    width: 100%;
    border-radius: 18px;
    background: #f6f8fc;
}

.explanation {
    border-top: 1px solid rgba(255,255,255,0.08);
    padding-top: 18px;
}

.explanation h3 {
    margin: 0 0 10px;
}

.explanation p {
    margin: 0 0 12px;
    color: var(--muted);
    line-height: 1.75;
}

.status-strip {
    display: grid;
    gap: 4px;
    padding: 16px 18px;
    border-radius: 18px;
    margin-top: 20px;
    border: 1px solid rgba(255,255,255,0.1);
}

.status-strip strong {
    font-size: 1.15rem;
}

.status-strip small,
.status-kicker {
    color: rgba(255,255,255,0.82);
}

.status-kicker {
    text-transform: uppercase;
    letter-spacing: .08em;
    font-size: 11px;
    font-weight: 700;
}

.status-ok {
    background: linear-gradient(135deg, rgba(82,210,115,0.22), rgba(0,210,184,0.16));
}

.status-warn {
    background: linear-gradient(135deg, rgba(255,209,102,0.20), rgba(255,171,76,0.15));
}

.status-danger {
    background: linear-gradient(135deg, rgba(255,125,125,0.22), rgba(255,87,87,0.15));
}

.results-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 14px;
    margin-top: 18px;
}

.result-item {
    padding: 18px;
}

.result-item.featured,
.result-item.accent {
    background: linear-gradient(135deg, rgba(76,196,255,0.14), rgba(123,140,255,0.10));
}

.result-label {
    display: block;
    margin-bottom: 10px;
    color: var(--muted);
    line-height: 1.45;
    font-size: .94rem;
}

.result-item strong {
    display: block;
    font-size: 1.35rem;
    line-height: 1.2;
}

.result-item em {
    font-style: normal;
    font-size: .9rem;
    color: #bdd8ff;
}

.empty-state {
    margin-top: 22px;
    padding: 22px;
    border-radius: 20px;
    border: 1px dashed rgba(255,255,255,0.18);
    background: rgba(255,255,255,0.03);
    color: var(--muted);
    line-height: 1.7;
}

.formula-list {
    display: grid;
    gap: 12px;
    margin-top: 22px;
}

.formula-list article {
    padding: 16px;
}

.formula-list strong {
    display: block;
    margin-bottom: 8px;
}

.formula-list span {
    color: var(--muted);
    line-height: 1.6;
}

@media (max-width: 980px) {
    .hero,
    .layout {
        grid-template-columns: 1fr;
    }

    .card-form,
    .card-visual,
    .card-results,
    .card-formulas {
        grid-column: span 1;
    }
}

@media (max-width: 640px) {
    .page-shell {
        width: min(100% - 18px, 100%);
        padding: 18px 0 34px;
    }

    .hero-copy,
    .hero-panel,
    .card {
        padding: 18px;
    }

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