:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --bg: #f8fafc;
    --text-dark: #1e293b;
    --text-light: #64748b;
    --card-bg: #ffffff;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg);
    color: var(--text-dark);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
}

.main-container { width: 100%; max-width: 450px; }

header { text-align: center; margin-bottom: 2rem; }

.brand { font-size: 2.5rem; font-weight: 700; letter-spacing: -1px; }
.brand span { color: var(--primary); }
header p { color: var(--text-light); font-size: 0.9rem; margin-top: 5px; }

.calculator-card {
    background: var(--card-bg);
    padding: 2.5rem;
    border-radius: 24px;
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

.input-section { margin-bottom: 1.5rem; }
label { display: block; font-size: 0.875rem; font-weight: 600; margin-bottom: 0.5rem; color: var(--text-light); }

input {
    width: 100%;
    padding: 15px;
    border: 2px solid #e2e8f0;
    border-radius: 12px;
    font-size: 1.1rem;
    transition: all 0.2s;
}

input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.1);
}

.action-buttons { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-bottom: 2rem; }

button {
    padding: 14px;
    border: none;
    border-radius: 12px;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.1s, background 0.2s;
}

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

.btn-log { background: var(--primary); color: white; }
.btn-log:hover { background: var(--primary-hover); }

.btn-antilog { background: #f1f5f9; color: var(--text-dark); }
.btn-antilog:hover { background: #e2e8f0; }

.result-container {
    text-align: center;
    padding: 20px;
    background: #fdfdfd;
    border: 2px solid #f1f5f9;
    border-radius: 16px;
}

.result-label { font-size: 0.75rem; text-transform: uppercase; letter-spacing: 1px; color: var(--text-light); }
.result-value { font-size: 1.8rem; font-weight: 700; color: var(--primary); margin-top: 8px; word-break: break-all; }

footer { text-align: center; margin-top: 2rem; font-size: 0.8rem; color: var(--text-light); }

/* Responsive adjustments */
@media (max-width: 400px) {
    .action-buttons { grid-template-columns: 1fr; }
    .calculator-card { padding: 1.5rem; }
}