:root {
    --bg: #f2f5fb;
    --surface: #ffffff;
    --surface-soft: #f8fafc;
    --text: #0f172a;
    --muted: #64748b;
    --primary: #ea580c;
    --primary-dark: #c2410c;
    --success: #16a34a;
    --warning-bg: #fff7ed;
    --warning-border: #ea580c;
    --error-bg: #fef2f2;
    --error-border: #dc2626;
    --border: #e2e8f0;
    --shadow: 0 18px 45px rgba(15, 23, 42, 0.1);
    --radius: 14px;
}

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

body {
    font-family: 'DM Sans', sans-serif;
    background: radial-gradient(1200px 400px at 20% -10%, #fed7aa, transparent), var(--bg);
    color: var(--text);
    line-height: 1.5;
}

body.drawer-open {
    overflow: hidden;
}

.calculator-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 30px 20px 60px;
}

.calculator-header {
    background: linear-gradient(120deg, #0f172a, #1e293b 60%, #334155);
    border-radius: 18px;
    padding: 28px;
    margin-bottom: 22px;
    color: #f8fafc;
    box-shadow: var(--shadow);
}

.header-top-row {
    display: flex;
    justify-content: space-between;
    gap: 18px;
    align-items: flex-start;
}

.eyebrow {
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: .08em;
    text-transform: uppercase;
    color: #fdba74;
    margin-bottom: 6px;
}

.calculator-header h1 {
    font-family: 'Playfair Display', serif;
    font-size: 2rem;
    margin-bottom: 8px;
}

.calculator-header p {
    color: #cbd5e1;
}

.cart-launch-btn {
    border: 1px solid rgba(251, 146, 60, 0.45);
    background: rgba(234, 88, 12, 0.2);
    color: #e2e8f0;
    padding: 12px 16px;
    border-radius: 12px;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    transition: all .2s ease;
}

.cart-launch-btn:hover {
    background: rgba(234, 88, 12, 0.35);
}

.cart-count {
    min-width: 24px;
    height: 24px;
    border-radius: 999px;
    background: #fdba74;
    color: #0f172a;
    display: inline-flex;
    justify-content: center;
    align-items: center;
    font-size: .8rem;
    font-weight: 700;
    padding: 0 8px;
}

.calculator-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 18px;
    box-shadow: var(--shadow);
    overflow: hidden;
}

.global-settings {
    padding: 24px;
    background: linear-gradient(180deg, #fff7ed, #f8fafc);
    border-bottom: 1px solid var(--border);
}

.tab-navigation {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    border-bottom: 1px solid var(--border);
    background: var(--surface-soft);
}

.tab-btn {
    border: none;
    background: transparent;
    color: var(--muted);
    padding: 16px 14px;
    font-weight: 600;
    font-size: .95rem;
    cursor: pointer;
    position: relative;
    transition: all .2s ease;
}

.tab-btn svg {
    width: 20px;
    height: 20px;
    display: block;
    margin: 0 auto 7px;
}

.tab-btn:hover {
    color: #1e293b;
    background: #fff;
}

.tab-btn.active {
    color: var(--primary-dark);
    background: #fff;
}

.tab-btn.active::after {
    content: '';
    position: absolute;
    left: 12%;
    right: 12%;
    bottom: 0;
    height: 3px;
    border-radius: 4px;
    background: var(--primary);
}

.tab-content {
    display: none;
    padding: 26px;
}

.tab-content.active {
    display: block;
}

.section-title {
    font-family: 'Playfair Display', serif;
    font-size: 1.22rem;
    margin-bottom: 14px;
    color: #0f172a;
}

.form-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
    gap: 14px;
    margin-bottom: 20px;
}

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

.form-group label {
    font-size: .8rem;
    font-weight: 700;
    color: #334155;
    margin-bottom: 7px;
}

.form-group .unit {
    color: #64748b;
    font-weight: 500;
}

.form-group input,
.form-group select {
    border: 1px solid #cbd5e1;
    background: #fff;
    border-radius: 10px;
    padding: 11px 12px;
    min-height: 46px;
    font-size: .95rem;
    line-height: 1.2;
    color: #0f172a;
    transition: all .2s ease;
}

.form-group select {
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
    padding-right: 42px;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 20 20' fill='none'%3E%3Cpath d='M5 7.5l5 5 5-5' stroke='%2394a3b8' stroke-width='1.8' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    background-size: 14px 14px;
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: #fb923c;
    box-shadow: 0 0 0 3px rgba(234, 88, 12, 0.15);
}

.calculate-btn {
    width: 100%;
    border: none;
    border-radius: 12px;
    background: linear-gradient(120deg, #ea580c, #c2410c);
    color: #fff;
    padding: 14px 18px;
    font-weight: 700;
    letter-spacing: .01em;
    cursor: pointer;
    transition: all .2s ease;
}

.calculate-btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 14px 28px rgba(234, 88, 12, .28);
}

.calculate-btn:disabled,
.calculate-btn.is-loading {
    opacity: .82;
    cursor: wait;
    transform: none;
    box-shadow: none;
}

.calculate-btn.is-loading::after {
    content: ' ...';
}

.validation-box {
    display: none;
    margin-top: 12px;
    border-left: 4px solid var(--warning-border);
    background: var(--warning-bg);
    border-radius: 10px;
    padding: 12px 14px;
}

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

.validation-box.has-errors {
    border-left-color: var(--error-border);
    background: var(--error-bg);
}

.validation-box h5 {
    margin-bottom: 7px;
    font-size: .9rem;
}

.validation-list {
    margin-left: 18px;
}

.validation-list li {
    margin-bottom: 4px;
    color: #334155;
    font-size: .88rem;
}

.results-section {
    display: none;
    margin-top: 14px;
    background: #f8fafc;
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 18px;
}

.results-section.show {
    display: block;
}

.results-header {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 14px;
}

.results-header svg {
    width: 24px;
    height: 24px;
    color: var(--success);
}

.results-header h3 {
    font-size: 1.1rem;
}

.results-grid {
    display: grid;
    gap: 10px;
    grid-template-columns: repeat(4, minmax(0, 1fr));
}

.result-item {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 14px;
}

.result-value {
    font-size: 1.5rem;
    font-weight: 800;
    color: #0f172a;
}

.result-value .unit {
    font-size: .85rem;
    font-weight: 600;
    color: #475569;
}

.result-label {
    margin-top: 4px;
    color: #64748b;
    font-size: .82rem;
}

.result-note {
    margin-top: 10px;
    color: #334155;
    font-size: .9rem;
}

.cart-section {
    display: none;
}

.cart-overlay {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.46);
    opacity: 0;
    pointer-events: none;
    transition: opacity .25s ease;
    z-index: 90;
}

.cart-overlay.show {
    opacity: 1;
    pointer-events: auto;
}

.cart-drawer {
    position: fixed;
    top: 0;
    right: 0;
    width: min(980px, 99vw);
    height: 100vh;
    background: #fff;
    border-left: 1px solid var(--border);
    box-shadow: -18px 0 40px rgba(15, 23, 42, 0.18);
    transform: translateX(105%);
    transition: transform .28s ease;
    z-index: 99;
    display: flex;
    flex-direction: column;
}

.cart-drawer.open {
    transform: translateX(0);
}

.cart-drawer-header {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    align-items: flex-start;
    padding: 20px;
    border-bottom: 1px solid var(--border);
    background: #f8fafc;
}

.cart-drawer-header h3 {
    font-size: 1.2rem;
    margin-bottom: 4px;
}

.drawer-context {
    color: var(--muted);
    font-size: .88rem;
}

.drawer-filters {
    display: inline-flex;
    gap: 8px;
    margin-top: 10px;
    flex-wrap: wrap;
}

.drawer-filter-btn {
    border: 2px solid #fdba74;
    background: #fff;
    color: #9a3412;
    min-height: 34px;
    padding: 6px 12px;
    border-radius: 999px;
    font-size: .78rem;
    font-weight: 700;
    cursor: pointer;
    transition: all .2s ease;
}

.drawer-filter-btn:hover {
    border-color: #fb923c;
    background: #fff7ed;
    color: #7c2d12;
}

.drawer-filter-btn.active {
    border-color: #ea580c;
    background: #fff7ed;
    color: #7c2d12;
    box-shadow: 0 0 0 2px rgba(234, 88, 12, .14);
}

.drawer-close-btn {
    border: 1px solid var(--border);
    background: #fff;
    width: 36px;
    height: 36px;
    border-radius: 10px;
    font-size: 1.1rem;
    cursor: pointer;
}

.drawer-cart-content {
    padding: 16px 18px 22px;
    overflow: auto;
}

.drawer-summary {
    border: 1px solid #fed7aa;
    background: #fff7ed;
    border-radius: 12px;
    padding: 12px 14px;
    margin-bottom: 14px;
}

.drawer-summary p {
    margin: 0;
    color: #7c2d12;
    font-size: .9rem;
}

.drawer-summary p + p {
    margin-top: 6px;
}

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

.cart-group h5 {
    color: #334155;
    margin-bottom: 8px;
}

.cart-table-wrap {
    width: 100%;
    overflow: auto;
}

.cart-table {
    width: 100%;
    border-collapse: collapse;
    min-width: 760px;
}

.cart-table th,
.cart-table td {
    border-bottom: 1px solid var(--border);
    padding: 10px 8px;
    text-align: left;
    font-size: .88rem;
}

.cart-table th {
    color: #334155;
    background: #f8fafc;
    font-weight: 700;
}

.cart-table .cart-cell-num {
    text-align: right;
    white-space: nowrap;
}

.cart-table tr.cart-row-low-stock td {
    background: #fff1f2;
}

.cart-table tr.cart-row-low-stock td:first-child {
    border-left: 4px solid #dc2626;
    padding-left: 10px;
}

.cart-table tr.cart-row-unavailable td {
    background: #fee2e2;
}

.cart-table tr.cart-row-unavailable td:first-child {
    border-left: 4px solid #991b1b;
    padding-left: 10px;
}

.cart-line-title {
    font-weight: 700;
}

.cart-line-meta {
    font-size: .78rem;
    color: #64748b;
    margin-top: 4px;
}

.cart-badge {
    margin-left: 6px;
    border-radius: 999px;
    font-size: .7rem;
    font-weight: 700;
    padding: 2px 7px;
}

.cart-badge.required {
    background: #ffedd5;
    color: #9a3412;
}

.cart-badge.optional {
    background: #f1f5f9;
    color: #334155;
}

.cart-badge.in-stock {
    background: #dcfce7;
    color: #166534;
}

.cart-badge.unavailable {
    background: #fee2e2;
    color: #991b1b;
}

.cart-badge.low-stock {
    background: #fecaca;
    color: #991b1b;
}

.cart-empty {
    color: #64748b;
    font-size: .92rem;
}

@media (max-width: 900px) {
    .results-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}

@media (max-width: 700px) {
    .calculator-container {
        padding: 18px 12px 36px;
    }

    .header-top-row {
        flex-direction: column;
    }

    .tab-navigation {
        grid-template-columns: repeat(2, 1fr);
    }

    .tab-content,
    .global-settings {
        padding: 16px;
    }

    .results-grid {
        grid-template-columns: 1fr;
    }
}