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

:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --text: #111827;
    --muted: #6b7280;
    --border: #e5e7eb;
    --bg: #f3f4f6;
    --white: #ffffff;
    --error-bg: #fef2f2;
    --error-border: #fecaca;
    --error-text: #dc2626;
    --result-bg: #eff6ff;
    --result-border: #bfdbfe;
    --result-accent: #1d4ed8;
}

body {
    font-family: 'Inter', sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    padding: 52px 16px 80px;
}

.container {
    width: 100%;
    max-width: 660px;
}

header {
    margin-bottom: 24px;
}

h1 {
    font-size: 22px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 5px;
}

.subtitle {
    font-size: 14px;
    color: var(--muted);
}

/* ── Card ── */
.card {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 32px;
    box-shadow: 0 1px 4px rgba(0,0,0,0.06);
}

/* ── Form ── */
.form-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 24px;
}

.field-group {
    display: flex;
    flex-direction: column;
    gap: 7px;
}

label {
    font-size: 13px;
    font-weight: 500;
    color: var(--text);
}

input[type="number"],
select {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-family: 'Inter', sans-serif;
    font-size: 14px;
    color: var(--text);
    background: var(--white);
    outline: none;
    transition: border-color 0.15s, box-shadow 0.15s;
    appearance: none;
    -webkit-appearance: none;
}

input[type="number"]:focus,
select:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.select-wrapper {
    position: relative;
}

.select-wrapper::after {
    content: '▾';
    position: absolute;
    right: 12px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--muted);
    pointer-events: none;
    font-size: 13px;
}

/* ── Toggles ── */
.toggle-group {
    display: flex;
    gap: 6px;
}

.toggle-btn {
    flex: 1;
    padding: 10px 4px;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: var(--white);
    font-family: 'Inter', sans-serif;
    font-size: 14px;
    font-weight: 500;
    color: var(--muted);
    cursor: pointer;
    transition: all 0.15s;
    text-align: center;
}

.toggle-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.toggle-btn.active {
    background: var(--primary);
    border-color: var(--primary);
    color: var(--white);
}

/* ── Button ── */
.predict-btn {
    width: 100%;
    padding: 13px;
    background: var(--primary);
    color: var(--white);
    border: none;
    border-radius: 9px;
    font-family: 'Inter', sans-serif;
    font-size: 15px;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.15s;
}

.predict-btn:hover {
    background: var(--primary-hover);
}

.predict-btn.loading {
    opacity: 0.65;
    cursor: not-allowed;
    pointer-events: none;
}

/* ── Error ── */
.error-box {
    display: none;
    margin-top: 16px;
    padding: 11px 14px;
    background: var(--error-bg);
    border: 1px solid var(--error-border);
    border-radius: 8px;
    color: var(--error-text);
    font-size: 13px;
}

.error-box.visible { display: block; }

/* ── Result ── */
.result-box {
    display: none;
    margin-top: 20px;
    padding: 24px 20px 20px;
    background: var(--result-bg);
    border: 1px solid var(--result-border);
    border-radius: 12px;
    text-align: center;
}

.result-box.visible { display: block; }

.result-label {
    font-size: 11px;
    font-weight: 600;
    color: var(--primary);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    margin-bottom: 10px;
}

/* Big readable number — no jargon */
.result-primary {
    font-size: 42px;
    font-weight: 600;
    color: var(--text);
    line-height: 1;
    margin-bottom: 20px;
    letter-spacing: -0.02em;
}

/* Three-way breakdown */
.result-breakdown {
    display: flex;
    align-items: stretch;
    justify-content: center;
    gap: 0;
    background: rgba(255,255,255,0.7);
    border: 1px solid var(--result-border);
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 14px;
}

.breakdown-item {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 4px;
    padding: 12px 10px;
    text-align: center;
}

.breakdown-divider {
    width: 1px;
    background: var(--result-border);
    flex-shrink: 0;
}

.breakdown-label {
    font-size: 11px;
    color: var(--muted);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.breakdown-value {
    font-size: 15px;
    font-weight: 600;
    color: var(--result-accent);
}

.result-note {
    font-size: 12px;
    color: var(--muted);
}

/* ── Spinner ── */
.spinner {
    display: inline-block;
    width: 14px;
    height: 14px;
    border: 2px solid rgba(255,255,255,0.4);
    border-top-color: #fff;
    border-radius: 50%;
    animation: spin 0.7s linear infinite;
    vertical-align: middle;
    margin-right: 6px;
}

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

/* ── Mobile ── */
@media (max-width: 500px) {
    .card { padding: 20px 16px; }
    .form-grid { grid-template-columns: 1fr; }
    .result-primary { font-size: 32px; }
    .breakdown-value { font-size: 13px; }
}