:root {
    --bg: #0f172a;
    --card: #111827;
    --card-2: #1f2937;
    --line: rgba(255, 255, 255, 0.1);
    --text: #f8fafc;
    --muted: #cbd5e1;
    --accent: #38bdf8;
    --accent-2: #22c55e;
    --danger: #f87171;
    --shadow: 0 20px 60px rgba(0, 0, 0, 0.35);
    --radius: 22px;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    font-family: Arial, Helvetica, sans-serif;
    background:
        radial-gradient(circle at top left, rgba(56, 189, 248, 0.14), transparent 25%),
        radial-gradient(circle at bottom right, rgba(34, 197, 94, 0.12), transparent 25%),
        linear-gradient(135deg, #020617, #0f172a 55%, #111827);
    color: var(--text);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 24px;
}

.wrap {
    width: 100%;
    max-width: 980px;
    display: grid;
    grid-template-columns: 1.1fr 0.9fr;
    gap: 24px;
}

.panel {
    background: rgba(17, 24, 39, 0.92);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    backdrop-filter: blur(8px);
}

.form-panel {
    padding: 32px;
}

.info-panel {
    padding: 28px;
    background: linear-gradient(180deg, rgba(31, 41, 55, 0.95), rgba(15, 23, 42, 0.95));
}

.eyebrow {
    display: inline-flex;
    padding: 8px 12px;
    border-radius: 999px;
    background: rgba(56, 189, 248, 0.12);
    color: #7dd3fc;
    font-size: 12px;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    margin-bottom: 16px;
}

h1 {
    margin: 0 0 10px;
    font-size: clamp(28px, 4vw, 42px);
    line-height: 1.05;
}

.lead {
    margin: 0 0 28px;
    color: var(--muted);
    line-height: 1.6;
}

.grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 18px;
}

.field,
.result-field {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.field.full,
.result-field.full {
    grid-column: 1 / -1;
}

label {
    font-size: 14px;
    color: #dbeafe;
    font-weight: 700;
}

input {
    width: 100%;
    border: 1px solid rgba(255, 255, 255, 0.12);
    background: rgba(255, 255, 255, 0.04);
    color: var(--text);
    border-radius: 14px;
    padding: 14px 16px;
    font-size: 16px;
    outline: none;
    transition: border-color .2s ease, transform .2s ease, background .2s ease;
}

input:focus {
    border-color: var(--accent);
    background: rgba(255, 255, 255, 0.07);
    transform: translateY(-1px);
}

input[readonly] {
    background: rgba(56, 189, 248, 0.08);
    border-color: rgba(56, 189, 248, 0.22);
}

.actions {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    margin-top: 26px;
}

button {
    border: 0;
    border-radius: 14px;
    padding: 14px 18px;
    font-size: 15px;
    font-weight: 700;
    cursor: pointer;
}

button[type="submit"] {
    background: linear-gradient(135deg, var(--accent), #2563eb);
    color: white;
    box-shadow: 0 14px 30px rgba(37, 99, 235, 0.28);
}

.ghost-button {
    background: rgba(255, 255, 255, 0.06);
    color: var(--text);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.errors {
    margin: 0 0 20px;
    padding: 14px 16px;
    border-radius: 14px;
    background: rgba(248, 113, 113, 0.12);
    border: 1px solid rgba(248, 113, 113, 0.28);
    color: #fecaca;
}

.errors ul,
.notes ul {
    margin: 0;
    padding-left: 18px;
}

.hidden {
    display: none;
}

.formula,
.notes {
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 18px;
    padding: 18px;
    background: rgba(255, 255, 255, 0.03);
}

.formula h2,
.notes h2 {
    margin-top: 0;
    font-size: 18px;
}

.formula code {
    display: block;
    background: rgba(2, 6, 23, 0.72);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 14px;
    padding: 12px 14px;
    color: #bae6fd;
    font-size: 14px;
    overflow-x: auto;
    margin-top: 10px;
}

.stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
    margin: 18px 0 22px;
}

.stat {
    padding: 18px;
    border-radius: 18px;
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid rgba(255, 255, 255, 0.08);
}

.stat span {
    display: block;
    color: var(--muted);
    font-size: 13px;
    margin-bottom: 8px;
}

.stat strong {
    font-size: 24px;
    color: white;
}

.hint {
    font-size: 13px;
    color: var(--muted);
    margin-top: 8px;
}

.ok {
    color: #86efac;
}

@media (max-width: 860px) {
    .wrap {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 640px) {
    .form-panel,
    .info-panel {
        padding: 22px;
    }

    .grid,
    .stats {
        grid-template-columns: 1fr;
    }
}