:root {
    --bg:           #f8fafc;
    --surface:      #ffffff;
    --border:       #e2e8f0;
    --text:         #1e293b;
    --muted:        #64748b;
    --primary:      #2563eb;
    --primary-bg:   #dbeafe;
    --success:      #16a34a;
    --danger:       #dc2626;
    --warn:         #d97706;
    --radius:       8px;
    --sidebar:      300px;
}

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

body {
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    background: var(--bg);
    color: var(--text);
    height: 100vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

/* ── Header ─────────────────────────────────────────────────────────────── */
header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 14px 28px;
    display: flex;
    align-items: baseline;
    gap: 16px;
    flex-shrink: 0;
}

header h1 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary);
    letter-spacing: -0.02em;
}

header .subtitle {
    font-size: 0.8rem;
    color: var(--muted);
}

/* ── Layout ─────────────────────────────────────────────────────────────── */
main {
    display: flex;
    flex: 1;
    min-height: 0;
    overflow: hidden;
}

/* ── Sidebar ─────────────────────────────────────────────────────────────── */
.controls {
    width: var(--sidebar);
    flex-shrink: 0;
    background: var(--surface);
    border-right: 1px solid var(--border);
    overflow-y: auto;
    padding: 20px 16px;
}

.control-section { margin-bottom: 22px; }

.section-label {
    display: block;
    font-size: 0.68rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.07em;
    color: var(--muted);
    margin-bottom: 8px;
}

/* Strategy buttons */
.strategy-buttons { display: flex; flex-direction: column; gap: 5px; }

.strategy-btn {
    padding: 8px 12px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--surface);
    color: var(--text);
    font-size: 0.82rem;
    font-weight: 500;
    cursor: pointer;
    text-align: left;
    transition: border-color 0.12s, color 0.12s, background 0.12s;
}
.strategy-btn:hover { border-color: var(--primary); color: var(--primary); }
.strategy-btn.active {
    background: var(--primary);
    border-color: var(--primary);
    color: #fff;
}

/* Ticker */
.ticker-input { display: flex; gap: 6px; margin-bottom: 8px; }

.ticker-input input {
    flex: 1;
    padding: 7px 10px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 0.82rem;
    outline: none;
    transition: border-color 0.12s;
    min-width: 0;
}
.ticker-input input:focus { border-color: var(--primary); }

#fetch-price-btn {
    padding: 7px 11px;
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: var(--radius);
    font-size: 0.8rem;
    font-weight: 600;
    cursor: pointer;
    white-space: nowrap;
    transition: opacity 0.12s;
}
#fetch-price-btn:disabled { opacity: 0.55; cursor: not-allowed; }

.quick-tickers { display: flex; flex-wrap: wrap; gap: 5px; margin-bottom: 10px; }

.ticker-chip {
    padding: 3px 9px;
    border: 1px solid var(--border);
    border-radius: 20px;
    background: var(--bg);
    color: var(--muted);
    font-size: 0.72rem;
    font-weight: 600;
    cursor: pointer;
    transition: border-color 0.12s, color 0.12s;
}
.ticker-chip:hover { border-color: var(--primary); color: var(--primary); }

#price-display {
    display: none;
    align-items: center;
    justify-content: space-between;
    padding: 8px 12px;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
}
#price-display.error { background: #fef2f2; border-color: #fca5a5; }

.ticker-name { font-size: 0.8rem; font-weight: 700; }
.ticker-price { font-size: 1rem; font-weight: 700; color: var(--primary); }
#price-display.error .ticker-price { color: var(--danger); font-size: 0.75rem; }

/* Sliders */
.slider-wrapper { margin-bottom: 16px; }

.slider-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    margin-bottom: 5px;
}

.slider-header label { font-size: 0.78rem; font-weight: 600; }
.slider-value { font-size: 0.72rem; color: var(--primary); font-weight: 600; }

input[type="range"] {
    width: 100%;
    accent-color: var(--primary);
    cursor: pointer;
    height: 4px;
}

.slider-desc { font-size: 0.68rem; color: var(--muted); margin-top: 4px; }

/* ── Content ─────────────────────────────────────────────────────────────── */
.content {
    flex: 1;
    min-width: 0;
    min-height: 0;
    overflow-y: auto;
    padding: 20px 24px;
    display: flex;
    flex-direction: column;
    gap: 14px;
}

/* Cards */
.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px 20px;
}

.card h2 {
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 4px;
    letter-spacing: -0.01em;
}

.hook {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--primary);
    margin-bottom: 8px;
}

.description {
    font-size: 0.82rem;
    color: var(--muted);
    line-height: 1.65;
}

.card-title {
    font-size: 0.78rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--muted);
    margin-bottom: 12px;
}

/* Example walkthrough card */
.card-example { border-left: 3px solid var(--primary); }

.example-context {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--muted);
    margin-bottom: 10px;
}

.example-steps {
    list-style: none;
    counter-reset: steps;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.example-steps li {
    counter-increment: steps;
    display: flex;
    gap: 10px;
    font-size: 0.82rem;
    line-height: 1.55;
    color: var(--text);
}

.example-steps li::before {
    content: counter(steps);
    min-width: 20px;
    height: 20px;
    background: var(--primary-bg);
    color: var(--primary);
    font-size: 0.7rem;
    font-weight: 700;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    margin-top: 1px;
}

/* Key points */
.key-points {
    display: flex;
    gap: 10px;
    margin-bottom: 14px;
}

.key-point {
    flex: 1;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 10px 12px;
    text-align: center;
}

.key-label {
    display: block;
    font-size: 0.65rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--muted);
    margin-bottom: 3px;
}

.key-value { font-size: 0.95rem; font-weight: 700; }
.key-value.profit { color: var(--success); }
.key-value.loss   { color: var(--danger); }

/* Mechanics */
.mechanics-list { list-style: none; display: flex; flex-direction: column; gap: 3px; }

.mechanics-list li {
    font-size: 0.78rem;
    color: var(--muted);
    padding-left: 14px;
    position: relative;
    line-height: 1.5;
}
.mechanics-list li::before {
    content: "›";
    color: var(--primary);
    font-weight: 700;
    position: absolute;
    left: 0;
}

/* Chart */
.chart-container {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 18px 20px;
    height: 300px;
    flex-shrink: 0;
    position: relative;
    display: flex;
    flex-direction: column;
}

#payoff-chart {
    flex: 1;
    min-height: 0;
}

.chart-title {
    display: flex;
    align-items: baseline;
    gap: 8px;
    margin-bottom: 10px;
}

.chart-subtitle {
    font-size: 0.65rem;
    font-weight: 400;
    text-transform: none;
    letter-spacing: 0;
    color: var(--muted);
}

/* Disclaimer */
footer {
    padding: 10px 28px;
    font-size: 0.68rem;
    color: var(--muted);
    border-top: 1px solid var(--border);
    background: var(--surface);
    flex-shrink: 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-credit {
    font-size: 0.62rem;
    color: var(--border);
    letter-spacing: 0.04em;
}

/* ── Responsive ──────────────────────────────────────────────────────────── */
@media (max-width: 900px) {
    body { height: auto; overflow: visible; }
    main { flex-direction: column; overflow: visible; }
    .controls {
        width: 100%;
        border-right: none;
        border-bottom: 1px solid var(--border);
    }
    .content { padding: 14px 16px; }
    .key-points { flex-wrap: wrap; }
    .chart-container { height: 260px; }
}