:root {
    --bg-color: #0b0f19;
    --panel-bg: #111827;
    --accent-color: #3b82f6;
    --secondary-accent: #8b5cf6;
    --text-color: #f3f4f6;
    --text-muted: #9ca3af;
    --border-color: #1f2937;
    --input-bg: #1f2937;
}

* {
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    line-height: 1.5;
}

.container {
    max-width: 1000px;
    margin: 40px auto;
    padding: 20px;
}

header {
    text-align: center;
    margin-bottom: 40px;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 800;
    background: linear-gradient(to right, var(--accent-color), var(--secondary-accent));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 10px;
}

header p {
    color: var(--text-muted);
}

.card {
    background-color: var(--panel-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 24px;
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.4);
}

.controls {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.form-group {
    display: flex;
    flex-direction: column;
}

.form-group label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-muted);
    margin-bottom: 8px;
}

.form-group input {
    background-color: var(--input-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-color);
    padding: 10px 14px;
    font-size: 1rem;
    transition: all 0.2s;
}

.form-group input:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

button {
    background: linear-gradient(to bottom right, var(--accent-color), var(--secondary-accent));
    border: none;
    border-radius: 8px;
    color: white;
    padding: 12px 24px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.1s, opacity 0.2s;
}

button:hover {
    opacity: 0.9;
}

button:active {
    transform: scale(0.98);
}

.chart-container {
    margin-top: 30px;
    position: relative;
    height: 500px;
    width: 100%;
}

.formula-display {
    margin-top: 30px;
    padding: 15px;
    background: rgba(255, 255, 255, 0.03);
    border-radius: 8px;
    font-family: 'Cambria Math', 'Times New Roman', serif;
    font-size: 1.1rem;
    color: #e5e7eb;
}

.formula-display i {
    color: var(--secondary-accent);
}

footer {
    text-align: center;
    margin-top: 50px;
    color: var(--text-muted);
    font-size: 0.875rem;
}