:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-main: #0f172a;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --success: #10b981;
}

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

.tool-container {
    max-width: 1000px;
    margin: 40px auto;
    padding: 0 20px;
}

.tool-header {
    text-align: center;
    margin-bottom: 32px;
}

.tool-header h1 {
    font-size: 2.25rem;
    font-weight: 800;
    color: var(--text-main);
    margin-bottom: 12px;
    letter-spacing: -0.02em;
}

.tool-header p {
    color: var(--text-muted);
    font-size: 1.1rem;
    max-width: 680px;
    margin: 0 auto;
    line-height: 1.6;
}

/* Calculator Card */
.calculator-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 32px;
    box-shadow: 0 10px 25px -5px rgba(0,0,0,0.05);
    margin-bottom: 32px;
}

/* Mode Switcher Tabs */
.calc-mode-switch {
    display: flex;
    gap: 8px;
    background: #f1f5f9;
    padding: 6px;
    border-radius: 10px;
    margin-bottom: 32px;
}

.mode-btn {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 16px;
    border: none;
    background: transparent;
    color: var(--text-muted);
    font-weight: 600;
    font-size: 14px;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
}

.mode-btn.active {
    background: #ffffff;
    color: var(--primary);
    box-shadow: 0 2px 4px rgba(0,0,0,0.06);
}

/* Calculator Grid */
.calc-grid {
    display: grid;
    grid-template-columns: 1fr 1.2fr;
    gap: 32px;
}

.inputs-section {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.form-group label {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-main);
}

.form-control {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid #cbd5e1;
    border-radius: 8px;
    font-size: 16px;
    font-family: inherit;
    color: var(--text-main);
    background: #ffffff;
    outline: none;
    transition: border-color 0.2s;
    box-sizing: border-box;
}

.form-control:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.input-with-icon {
    position: relative;
    display: flex;
    align-items: center;
}

.currency-prefix {
    position: absolute;
    left: 14px;
    color: var(--text-muted);
    font-weight: 600;
    font-size: 16px;
}

.input-with-icon input {
    width: 100%;
    padding: 12px 16px 12px 32px;
    border: 1px solid #cbd5e1;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    color: var(--text-main);
    outline: none;
    transition: border-color 0.2s;
    box-sizing: border-box;
}

.input-with-icon input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.suffix-icon {
    position: absolute;
    right: 14px;
    color: var(--text-muted);
    font-weight: 600;
    font-size: 16px;
}

/* Results Section */
.results-section {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.result-card {
    background: #f8fafc;
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 16px;
    transition: all 0.2s;
}

.primary-result {
    background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
    border-color: #bfdbfe;
    padding: 20px;
}

.primary-result .result-label {
    color: #1e40af;
    font-size: 14px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.primary-result .result-value {
    color: #1e3a8a;
    font-size: 2.25rem;
    font-weight: 800;
    margin-top: 4px;
}

.results-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

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

.result-value {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-main);
    margin-top: 4px;
}

/* Info & Formula Card */
.info-card {
    background: #ffffff;
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 28px;
    margin-bottom: 32px;
}

.info-card h3 {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1.15rem;
    color: var(--text-main);
    margin-bottom: 20px;
}

.formula-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.formula-box {
    background: #f8fafc;
    border: 1px solid #e2e8f0;
    border-radius: 10px;
    padding: 16px;
}

.formula-box h4 {
    font-size: 1rem;
    color: var(--primary);
    margin-bottom: 6px;
}

.formula-box p {
    font-size: 13px;
    color: var(--text-muted);
    margin-bottom: 12px;
    line-height: 1.5;
}

.formula-box code {
    display: block;
    background: #1e293b;
    color: #38bdf8;
    padding: 8px 12px;
    border-radius: 6px;
    font-size: 12px;
    font-family: monospace;
}

/* Responsive Overrides */
@media (max-width: 768px) {
    .calc-grid {
        grid-template-columns: 1fr;
    }
    .results-grid {
        grid-template-columns: 1fr;
    }
    .formula-grid {
        grid-template-columns: 1fr;
    }
    .calc-mode-switch {
        flex-direction: column;
    }
}