/* ===== Base Reset & Layout ===== */
* { margin: 0; padding: 0; box-sizing: border-box; }

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    font-size: 15px;
    line-height: 1.6;
    color: #333;
    background: #f5f7fa;
}

.layout {
    display: flex;
    min-height: 100vh;
}

/* ===== Sidebar ===== */
.sidebar {
    width: 260px;
    background: #1a2a3a;
    color: #fff;
    flex-shrink: 0;
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    overflow-y: auto;
    z-index: 100;
}

.sidebar-header h1 {
    padding: 24px 20px 16px;
    font-size: 22px;
    font-weight: 700;
}

.sidebar-header h1 a {
    color: #fff;
    text-decoration: none;
}

.sidebar-nav ul {
    list-style: none;
}

.sidebar-nav li a {
    display: block;
    padding: 12px 20px;
    color: #b0c4d8;
    text-decoration: none;
    font-size: 14px;
    border-left: 3px solid transparent;
    transition: background 0.15s, color 0.15s;
}

.sidebar-nav li a:hover {
    background: rgba(255,255,255,0.08);
    color: #fff;
}

.sidebar-nav li a.active {
    background: rgba(255,255,255,0.12);
    border-left-color: #4a90d9;
    color: #fff;
}

/* ===== Content ===== */
.content {
    flex: 1;
    margin-left: 260px;
    padding: 0;
}

.content-inner {
    max-width: 760px;
    margin: 0 auto;
    padding: 40px 30px 60px;
}

.content-inner h2 {
    font-size: 28px;
    margin-bottom: 12px;
    color: #1a2a3a;
}

.content-inner > p {
    margin-bottom: 24px;
    color: #555;
}

/* ===== Cards (home page) ===== */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 16px;
    margin-bottom: 30px;
}

.card {
    display: block;
    background: #fff;
    border: 1px solid #e0e6ed;
    border-radius: 8px;
    padding: 20px;
    text-decoration: none;
    color: inherit;
    transition: box-shadow 0.15s, border-color 0.15s;
}

.card:hover {
    box-shadow: 0 2px 12px rgba(0,0,0,0.08);
    border-color: #b0c4d8;
}

.card h3 {
    font-size: 16px;
    color: #1a2a3a;
    margin-bottom: 6px;
}

.card p {
    font-size: 13px;
    color: #777;
}

/* ===== Calculator Forms ===== */
.calc-form {
    background: #fff;
    border: 1px solid #e0e6ed;
    border-radius: 8px;
    padding: 28px;
    margin-bottom: 24px;
}

.form-group {
    margin-bottom: 18px;
}

.form-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 6px;
    color: #1a2a3a;
    font-size: 14px;
}

.form-group .hint {
    font-weight: 400;
    color: #888;
    font-size: 12px;
    margin-top: 4px;
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid #ccd5e0;
    border-radius: 6px;
    font-size: 15px;
    font-family: inherit;
    color: #333;
    background: #fff;
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: #4a90d9;
    box-shadow: 0 0 0 2px rgba(74,144,217,0.15);
}

.form-row {
    display: flex;
    gap: 16px;
}

.form-row .form-group {
    flex: 1;
}

.radio-group {
    display: flex;
    gap: 20px;
}

.radio-group label {
    display: flex;
    align-items: center;
    gap: 6px;
    font-weight: 400;
    cursor: pointer;
}

.radio-group input[type="radio"] {
    width: auto;
}

.btn {
    display: inline-block;
    background: #4a90d9;
    color: #fff;
    border: none;
    padding: 12px 32px;
    border-radius: 6px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.15s;
}

.btn:hover {
    background: #3a7bc8;
}

.btn:active {
    background: #2d6ab0;
}

/* ===== Results ===== */
.result-box {
    background: #eef4fb;
    border: 1px solid #c5d9ee;
    border-radius: 8px;
    padding: 24px;
    margin-bottom: 24px;
    display: none;
}

.result-box.show {
    display: block;
}

.result-box h3 {
    font-size: 18px;
    color: #1a2a3a;
    margin-bottom: 12px;
}

.result-box .big-number {
    font-size: 42px;
    font-weight: 700;
    color: #4a90d9;
    margin: 8px 0;
}

.result-box .result-label {
    font-size: 14px;
    color: #666;
}

.result-box table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 16px;
}

.result-box table th,
.result-box table td {
    text-align: left;
    padding: 8px 12px;
    border-bottom: 1px solid #d5e0ee;
    font-size: 14px;
}

.result-box table th {
    color: #1a2a3a;
    font-weight: 600;
}

.result-box table td:last-child {
    text-align: right;
    font-weight: 600;
}

/* ===== Info / References ===== */
.info-box {
    background: #fff;
    border: 1px solid #e0e6ed;
    border-radius: 8px;
    padding: 24px;
    margin-bottom: 24px;
}

.info-box h3 {
    font-size: 16px;
    color: #1a2a3a;
    margin-bottom: 10px;
}

.info-box p,
.info-box li {
    font-size: 14px;
    color: #555;
    margin-bottom: 8px;
}

.info-box ul {
    padding-left: 20px;
}

.info-box a {
    color: #4a90d9;
}

/* ===== Disclaimer ===== */
.disclaimer {
    background: #fff8e1;
    border: 1px solid #ffe082;
    border-radius: 8px;
    padding: 16px 20px;
    margin-top: 30px;
}

.disclaimer p {
    font-size: 13px;
    color: #7a6600;
}

/* ===== Mobile ===== */
@media (max-width: 768px) {
    .sidebar {
        position: relative;
        width: 100%;
        height: auto;
    }
    .content {
        margin-left: 0;
    }
    .layout {
        flex-direction: column;
    }
    .form-row {
        flex-direction: column;
        gap: 0;
    }
}