:root {
    --bg-main: #0f172a;
    --card-bg: #1e293b;
    --card-inner: #0f172a;
    --accent-blue: #0ea5e9;
    --accent-hover: #0284c7;
    --accent-green: #10b981;
    --text-primary: #f8fafc;
    --text-muted: #94a3b8;
    --border-color: #334155;
    --warning-bg: rgba(245, 158, 11, 0.1);
    --warning-border: #f59e0b;
    --font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: var(--font-family);
}

body {
    background-color: var(--bg-main);
    color: var(--text-primary);
    display: flex;
    justify-content: center;
    align-items: flex-start;
    min-height: 100vh;
    padding: 16px;
    position: relative;
}

.app-container {
    width: 100%;
    max-width: 580px;
}

/* Оновлена плашка логотипу FORTI (висота іконки 40px) */
.header {
    text-align: center;
    margin-bottom: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.site-logo-badge {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    padding: 12px 28px;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    background: var(--card-bg);
    margin-bottom: 12px;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.3);
}

.site-logo-badge .logo-img {
    height: 40px;
    width: auto;
    display: block;
}

.site-logo-badge .logo-text {
    font-size: 32px;
    font-weight: 800;
    letter-spacing: 4px;
    color: var(--text-primary);
    line-height: 1;
}

.header .subtitle {
    font-size: 13px;
    color: var(--text-muted);
    margin-top: 4px;
}

.calculator-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 24px;
    box-shadow: 0 15px 25px -5px rgba(0, 0, 0, 0.5);
}

/* Перемикач режимів калькулятора (Таби) */
/* Сітка табів 2х2 для симетрії на мобільних */
.calc-tabs {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 8px;
    margin-bottom: 20px;
}

.tab-btn {
    width: 100%;
    padding: 12px 8px;
    background: var(--card-inner);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-muted);
    font-size: 13px;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: center;
    display: flex;
    align-items: center;
    justify-content: center;
}

.tab-btn:hover {
    color: var(--text-primary);
    border-color: var(--accent-blue);
}

.tab-btn.active {
    border-color: var(--accent-blue);
    color: var(--text-primary);
    background: var(--card-bg);
    box-shadow: 0 0 10px rgba(14, 165, 233, 0.15);
}

.form-group {
    margin-bottom: 16px;
}

.form-group label {
    display: block;
    font-size: 12px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-muted);
    margin-bottom: 6px;
}

.form-control {
    width: 100%;
    padding: 12px 14px;
    background: var(--card-inner);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-primary);
    font-size: 15px;
    outline: none;
    transition: border-color 0.2s;
}

.form-control:focus {
    border-color: var(--accent-blue);
}

.form-control:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn {
    width: 100%;
    padding: 14px;
    border: none;
    border-radius: 8px;
    font-size: 15px;
    font-weight: 700;
    cursor: pointer;
    transition: background 0.2s;
}

.btn-primary {
    background: var(--accent-blue);
    color: #ffffff;
}

.btn-primary:hover:not(:disabled) {
    background: var(--accent-hover);
}

.btn-primary:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

.btn-success {
    background: var(--accent-green);
    color: #ffffff;
    margin-top: 16px;
}

.btn-success:hover {
    background: #059669;
}

.loader-block {
    text-align: center;
    padding: 20px 0;
    color: var(--text-muted);
    font-size: 14px;
}

.spinner {
    width: 28px;
    height: 28px;
    border: 3px solid var(--border-color);
    border-top-color: var(--accent-blue);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin: 0 auto 10px auto;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.result-card {
    margin-top: 24px;
    padding-top: 20px;
    border-top: 1px solid var(--border-color);
    animation: fadeIn 0.3s ease-in-out;
}

.result-card h3 {
    font-size: 18px;
    color: var(--accent-blue);
    margin-bottom: 4px;
}

.engine-code {
    font-size: 13px;
    color: var(--text-muted);
    margin-bottom: 16px;
}

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

.spec-item {
    background: var(--card-inner);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 14px;
}

.spec-item h4 {
    font-size: 14px;
    color: var(--text-primary);
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    gap: 6px;
}

.spec-item p {
    font-size: 13px;
    color: var(--text-muted);
    margin-bottom: 4px;
    display: flex;
    justify-content: space-between;
}

.spec-item p strong {
    color: var(--text-primary);
    text-align: right;
}

.techdoc-notice {
    background: var(--warning-bg);
    border: 1px solid var(--warning-border);
    color: #fcd34d;
    padding: 12px;
    border-radius: 8px;
    font-size: 12px;
    line-height: 1.4;
    margin-top: 16px;
}

.modal-overlay {
    position: fixed !important;
    top: 0 !important;
    left: 0 !important;
    width: 100vw !important;
    height: 100vh !important;
    background: rgba(15, 23, 42, 0.85) !important;
    backdrop-filter: blur(6px);
    -webkit-backdrop-filter: blur(6px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 99999 !important;
    padding: 16px;
}

.modal-content {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 24px;
    width: 100%;
    max-width: 420px;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.7);
    animation: fadeIn 0.2s ease-in-out;
}

.modal-content h3 {
    color: var(--accent-blue);
    font-size: 18px;
    margin-bottom: 8px;
}

.modal-content p {
    font-size: 13px;
    color: var(--text-muted);
    line-height: 1.4;
}

.btn-cancel {
    width: 100%;
    background: transparent;
    border: none;
    color: var(--text-muted);
    padding: 10px;
    margin-top: 8px;
    font-size: 13px;
    cursor: pointer;
}

.btn-cancel:hover {
    color: var(--text-primary);
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}