:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --bg-body: #f8fafc;
    --bg-card: #ffffff;
    --text-main: #0f172a;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --success: #10b981;
    --radius: 0.75rem;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: --bg-body;
    color: var(--text-main);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
    width: 100%;
}

/* Navbar */
.navbar {
    background: var(--bg-card);
    border-bottom: 1px solid var(--border);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 10;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-weight: 700;
    font-size: 1.5rem;
    color: var(--primary);
    text-decoration: none;
}

.nav-links a {
    margin-left: 1.5rem;
    color: var(--text-main);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

.nav-links a:hover {
    color: var(--primary);
}

/* Main Layout */
main {
    flex: 1;
    padding: 2rem 0;
}

.grid-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    align-items: start;
}

@media (max-width: 768px) {
    .grid-layout {
        grid-template-columns: 1fr;
    }
}

/* Cards */
.card {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
}

h1 {
    font-size: 2.25rem;
    margin-bottom: 1rem;
    line-height: 1.2;
}

h2 {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
}

p {
    margin-bottom: 1rem;
    color: var(--text-muted);
}

/* Forms */
.form-group {
    margin-bottom: 1.25rem;
}

label {
    display: block;
    font-weight: 500;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
}

input, select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border);
    border-radius: 0.5rem;
    font-size: 1rem;
    font-family: inherit;
    transition: border-color 0.2s;
}

input:focus, select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

button.btn-primary {
    background: var(--primary);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    cursor: pointer;
    width: 100%;
    font-size: 1rem;
    transition: background 0.2s;
}

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

/* Results */
.result-box {
    text-align: center;
    padding: 1.5rem;
    background: #f0f9ff;
    border-radius: 0.5rem;
    margin-bottom: 1.5rem;
}

.result-value {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary);
}

.result-label {
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    font-weight: 600;
}

.chart-container {
    margin-top: 2rem;
    position: relative;
    height: 300px;
}

.hidden {
    display: none;
}

/* Footer */
.footer {
    background: var(--bg-card);
    border-top: 1px solid var(--border);
    padding: 2rem 0;
    margin-top: auto;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.875rem;
}