:root {
    --bg: #f3f6f3;
    --surface: #ffffff;
    --text: #15231b;
    --muted: #55655c;
    --border: #d5ded8;
    --green: #1c7a4c;
    --green-dark: #145c39;
    --green-soft: #e7f3ec;
    --error: #a4262c;
    --error-soft: #fbeaea;
    --info: #1d5a8a;
    --info-soft: #e8f1f8;
    --radius: 14px;
    --focus: 0 0 0 3px #ffffff, 0 0 0 6px #1c7a4c;
}

*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    font-size: 16px;
    line-height: 1.55;
}

.skip-link {
    position: absolute;
    left: 16px;
    top: -60px;
    padding: 10px 16px;
    background: var(--green-dark);
    color: #fff;
    border-radius: 8px;
    z-index: 10;
}

.skip-link:focus {
    top: 16px;
}

.page {
    max-width: 1120px;
    margin: 0 auto;
    padding: 48px 20px 40px;
}

.page-header {
    max-width: 680px;
    margin-bottom: 36px;
}

.eyebrow {
    margin: 0 0 10px;
    color: var(--green-dark);
    font-size: 0.8rem;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

h1 {
    margin: 0 0 12px;
    font-size: clamp(1.8rem, 4.5vw, 2.6rem);
    line-height: 1.15;
    letter-spacing: -0.02em;
}

.intro {
    margin: 0;
    color: var(--muted);
    font-size: 1.05rem;
}

.layout {
    display: grid;
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
    gap: 28px;
    align-items: start;
}

.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 32px;
    box-shadow: 0 1px 2px rgba(21, 35, 27, 0.04), 0 8px 24px rgba(21, 35, 27, 0.05);
}

.card h2 {
    margin: 0 0 24px;
    font-size: 1.2rem;
}

.card h3 {
    margin: 28px 0 10px;
    color: var(--muted);
    font-size: 0.8rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

/* Form */

.field,
fieldset.field {
    margin: 0 0 22px;
    padding: 0;
    border: 0;
    min-width: 0;
}

.field-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

label,
legend {
    display: block;
    margin-bottom: 6px;
    padding: 0;
    font-weight: 600;
}

.optional {
    color: var(--muted);
    font-weight: 400;
}

input[type="text"],
input[type="number"] {
    width: 100%;
    min-height: 46px;
    padding: 10px 14px;
    border: 1px solid #8b9a91;
    border-radius: 10px;
    background: #fff;
    color: var(--text);
    font: inherit;
}

input::placeholder {
    color: #7b8a81;
}

input:focus-visible,
.btn:focus-visible,
a:focus-visible {
    outline: none;
    box-shadow: var(--focus);
}

input[aria-invalid="true"] {
    border-color: var(--error);
    border-width: 2px;
}

.input-unit {
    display: flex;
}

.input-unit input {
    border-radius: 10px 0 0 10px;
    position: relative;
}

.input-unit input:focus-visible {
    z-index: 1;
}

.unit {
    display: flex;
    align-items: center;
    min-width: 68px;
    justify-content: center;
    padding: 0 14px;
    border: 1px solid #8b9a91;
    border-left: 0;
    border-radius: 0 10px 10px 0;
    background: var(--bg);
    color: var(--muted);
    font-weight: 600;
}

.hint {
    margin: 6px 0 0;
    color: var(--muted);
    font-size: 0.88rem;
}

.field-error {
    margin: 6px 0 0;
    color: var(--error);
    font-size: 0.9rem;
    font-weight: 600;
}

.fuel-options {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
}

.fuel-option {
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 2px;
    margin: 0;
    padding: 12px 14px;
    border: 1px solid #8b9a91;
    border-radius: 10px;
    cursor: pointer;
    transition: background-color 0.15s, border-color 0.15s;
}

.fuel-option input {
    position: absolute;
    opacity: 0;
    inset: 0;
    width: 100%;
    height: 100%;
    margin: 0;
    cursor: pointer;
}

.fuel-name {
    font-weight: 700;
}

.fuel-meta {
    color: var(--muted);
    font-size: 0.82rem;
    font-weight: 400;
}

.fuel-option:hover {
    border-color: var(--green);
}

.fuel-option:has(input:checked) {
    border-color: var(--green);
    background: var(--green-soft);
    box-shadow: inset 0 0 0 1px var(--green);
}

.fuel-option:has(input:checked) .fuel-name {
    color: var(--green-dark);
}

.fuel-option:has(input:focus-visible) {
    box-shadow: var(--focus);
}

.actions {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 30px;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 48px;
    padding: 0 22px;
    border: 1px solid transparent;
    border-radius: 10px;
    font: inherit;
    font-weight: 700;
    text-decoration: none;
    cursor: pointer;
    transition: background-color 0.15s;
}

.btn-primary {
    flex: 1 1 220px;
    background: var(--green);
    color: #fff;
}

.btn-primary:hover {
    background: var(--green-dark);
}

.btn-primary[aria-disabled="true"] {
    background: #6f8479;
    cursor: progress;
}

.btn-secondary {
    background: #fff;
    border-color: #8b9a91;
    color: var(--text);
}

.btn-secondary:hover {
    background: var(--bg);
}

/* Alerts */

.alert {
    margin: 0 0 22px;
    padding: 14px 16px;
    border-radius: 10px;
    border-left: 4px solid;
}

.alert ul {
    margin: 8px 0 0;
    padding-left: 20px;
}

.alert a {
    color: inherit;
}

.alert-success {
    background: var(--green-soft);
    border-color: var(--green);
    color: #0f4a2d;
}

.alert-info {
    background: var(--info-soft);
    border-color: var(--info);
    color: #143f61;
}

.alert-error {
    background: var(--error-soft);
    border-color: var(--error);
    color: #7a1a1f;
}

/* Result */

.result {
    border-top: 4px solid var(--green);
}

.result-top {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    margin-bottom: 24px;
}

.result-top h2 {
    margin: 0;
}

.badge {
    padding: 4px 12px;
    border-radius: 999px;
    background: var(--bg);
    color: var(--muted);
    font-size: 0.8rem;
    font-weight: 700;
    white-space: nowrap;
}

[data-state="saved"] .badge {
    background: var(--green);
    color: #fff;
}

.result-label {
    margin: 0;
    color: var(--muted);
    font-weight: 600;
}

.result-total {
    margin: 4px 0 0;
    font-size: clamp(2.4rem, 7vw, 3.4rem);
    font-weight: 800;
    line-height: 1.1;
    letter-spacing: -0.03em;
    color: var(--green-dark);
    overflow-wrap: anywhere;
}

[data-state="empty"] .result-total {
    color: #8b9a91;
}

.result-total-unit {
    font-size: 1.15rem;
    font-weight: 700;
    letter-spacing: 0;
    color: var(--text);
}

.result-sub {
    margin: 4px 0 0;
    color: var(--muted);
}

.result-empty {
    margin: 14px 0 0;
    color: var(--muted);
    font-size: 0.92rem;
}

.metrics {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1px;
    margin: 26px 0 0;
    border: 1px solid var(--border);
    border-radius: 10px;
    background: var(--border);
    overflow: hidden;
}

.metrics > div {
    padding: 14px 16px;
    background: #fff;
}

.metrics > div:last-child:nth-child(odd) {
    grid-column: 1 / -1;
}

dt {
    color: var(--muted);
    font-size: 0.82rem;
}

dd {
    margin: 2px 0 0;
    font-size: 1.05rem;
    font-weight: 700;
    overflow-wrap: anywhere;
}

dd small {
    color: var(--muted);
    font-size: 0.82rem;
    font-weight: 500;
}

code {
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: 0.88rem;
}

.assumptions {
    margin: 0;
    padding-left: 20px;
    color: var(--muted);
    font-size: 0.92rem;
}

.assumptions li + li {
    margin-top: 6px;
}

.saved-meta {
    margin: 24px 0 0;
    padding-top: 18px;
    border-top: 1px solid var(--border);
}

.saved-meta > div {
    display: flex;
    gap: 12px;
    justify-content: space-between;
    padding: 3px 0;
}

.saved-meta dd {
    font-size: 0.88rem;
    font-weight: 600;
    text-align: right;
}

.page-footer {
    margin-top: 32px;
    color: var(--muted);
    font-size: 0.88rem;
    text-align: center;
}

[hidden] {
    display: none !important;
}

@media (max-width: 880px) {
    .layout {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 520px) {
    .page {
        padding: 28px 16px 32px;
    }

    .card {
        padding: 22px 18px;
    }

    .field-row,
    .metrics {
        grid-template-columns: 1fr;
    }

    .field-row {
        gap: 0;
    }

    .btn {
        flex: 1 1 100%;
    }
}

@media (prefers-reduced-motion: reduce) {
    * {
        transition: none !important;
    }
}