:root {
    --blue: #123f66;
    --accent: #e59b22;
    --ink: #1f2b35;
    --soft: #f3f7f9;
    --line: #d7e1e7;
}

* {
    box-sizing: border-box;
}


main {
    padding: 10px 0 60px;
}

.wrap {
    width: min(100% - 40px, 1220px);
    margin: auto;
    padding: 10px 20px 0 20px;
}

h1 {
    margin: 0;
    font-size: clamp(1.8rem, 5vw, 2rem);
    line-height: 1.15;
}


.grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
}

.calculator {
    padding: 22px;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: var(--soft);
}

h2 {
    margin: 0 0 7px;
    color: var(--blue);
    font-size: 1.3rem;
    line-height: 1.25;
}

h3{
    font-size:1.2rem;
}

.intro {
    min-height: 54px;
    margin: 0 0 18px;
    color: #52636d;
    font-size: .93rem;
}

label {
    display: block;
    margin: 13px 0 5px;
    font-weight: bold;
    font-size: .93rem;
}

input, select {
    width: 100%;
    padding: 11px;
    border: 1px solid #aebfc9;
    border-radius: 4px;
    background: #fff;
    color: var(--ink);
    font: inherit;
}

    input:focus {
        outline: 3px solid rgba(18, 63, 102, .2);
        border-color: var(--blue);
    }

main button {
    width: 100%;
    margin-top: 18px;
    padding: 11px;
    border: 0;
    border-radius: 4px;
    background: var(--accent);
    color: #172b3a;
    font: inherit;
    font-weight: bold;
    cursor: pointer;
}

   main button:hover {
        background: #cc8413;
    }

.answer {
    min-height: 68px;
    margin-top: 18px;
    padding: 14px;
    border-left: 4px solid var(--blue);
    background: #fff;
}

    .answer strong {
        display: block;
        color: var(--blue);
        font-size: 1.35rem;
    }

.error {
    color: #a32323;
}

.data-entry {
    width: 100%;
    min-height: 130px;
    padding: 12px;
    resize: vertical;
    border: 1px solid #aebfc9;
    border-radius: 4px;
    color: var(--ink);
    font: inherit;
}

.data-entry:focus {
    outline: 3px solid rgba(18, 63, 102, .2);
    border-color: var(--blue);
}

.results-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 12px;
    margin: 22px 0;
}

.stat {
    padding: 16px;
    border: 1px solid var(--line);
    border-radius: 6px;
    background: var(--soft);
}

.stat span {
    display: block;
    color: #52636d;
    font-size: .87rem;
}

.stat strong {
    display: block;
    margin-top: 3px;
    color: var(--blue);
    font-size: 1.25rem;
    overflow-wrap: anywhere;
}

.formula {
    margin: 18px 0;
    padding: 17px 20px;
    border-left: 4px solid var(--accent);
    background: #fff8e9;
}

.guide {
    max-width: 760px;
    margin: 46px 0 0 0;
}

    .guide section {
        margin-bottom: 34px;
    }

    .guide h2 {
        font-size: 1.5rem;
    }

footer {
    padding: 21px 20px;
    color: #fff;
    background: var(--blue);
}

footer p {
    margin: 0;
}

.tools,
.categories {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-top: 25px;
}

.tool,
.category {
    display: flex;
    flex-direction: column;
    min-height: 220px;
    padding: 24px;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: var(--soft);
}

.tool h3,
.category h3 {
    margin: 10px 0 9px 0;
    color: var(--blue);
    font-size: 1.25rem;
}

.tool p,
.category p {
    margin: 0;
}

.button,
.link {
    display: inline-block;
    margin-top: auto;
    padding-top: 18px;
    color: #124f78;
    font-weight: bold;
    text-decoration: none;
}

.button:hover,
.link:hover {
    color: #8e5606;
    text-decoration: underline;
}

.about,
.content {
    max-width: 760px;
    margin:0;
}

.about section,
.content section {
    margin-bottom: 34px;
}

.about h2,
.content h2 {
    margin-bottom: 10px;
    font-size: 1.55rem;
}

ul {
    padding-left: 24px;
}

.compact-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
}

.ratio-sign {
    display: grid;
    place-items: end center;
    padding-bottom: 9px;
    color: var(--blue);
    font-size: 1.25rem;
    font-weight: bold;
}

.ratio-row {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: 8px;
    align-items: end;
}

.proportion-layout {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: 18px;
    align-items: center;
    max-width: 620px;
    margin: 22px auto;
}

.fraction-fields {
    display: grid;
    gap: 10px;
}

.fraction-fields input:first-child {
    border-bottom: 3px solid var(--blue);
}

.equals-sign {
    color: var(--blue);
    font-size: 1.6rem;
    font-weight: bold;
}

.fraction-calculation {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: 18px;
    align-items: end;
    max-width: 820px;
    margin: 22px auto;
}

.mixed-number-inputs {
    display: grid;
    grid-template-columns: .8fr 1fr 1fr;
    gap: 8px;
}

.operator-select {
    width: auto;
    min-width: 70px;
    font-weight: bold;
}

.tool-tabs {
    display: flex;
    gap: 8px;
    margin: 0 0 22px;
    padding: 4px 0 8px;
    overflow-x: auto;
    scrollbar-width: thin;
}

.tool-tabs a {
    flex: 0 0 auto;
    padding: 9px 14px;
    border: 1px solid var(--line);
    border-radius: 999px;
    background: var(--surface, #fff);
    color: var(--ink);
    text-decoration: none;
    white-space: nowrap;
}

.tool-tabs a[aria-current="page"] {
    border-color: var(--blue);
    background: var(--blue);
    color: #fff;
}

.weight-row {
    display: grid;
    grid-template-columns: minmax(72px, .6fr) minmax(110px, 1fr) minmax(110px, 1fr) auto;
    gap: 10px;
    align-items: end;
    margin-bottom: 10px;
}

.weight-row input,
.weight-row button {
    margin: 0;
}

.row-number {
    padding-bottom: 11px;
    font-weight: 700;
}

.result-table-wrap {
    overflow-x: auto;
}

.result-table {
    width: 100%;
    border-collapse: collapse;
}

.result-table th,
.result-table td {
    padding: 9px;
    border-bottom: 1px solid var(--line);
    text-align: right;
}

.result-table th:first-child,
.result-table td:first-child {
    text-align: left;
}

.rule-table th:nth-child(3),
.rule-table td:nth-child(3) {
    text-align: left;
}

.factor-tree-wrap {
    margin-top: 12px;
    padding: 16px;
    overflow-x: auto;
    border: 1px solid var(--line);
    border-radius: 10px;
    background: #fff;
}

.factor-tree,
.factor-tree ul {
    margin: 0;
    padding-left: 24px;
    list-style: none;
}

.factor-tree > li {
    padding-left: 0;
}

.factor-tree li {
    position: relative;
    min-width: max-content;
    padding: 4px 0 4px 16px;
}

.factor-tree ul {
    border-left: 2px solid var(--line);
}

.factor-tree ul > li::before {
    content: "";
    position: absolute;
    top: 16px;
    left: 0;
    width: 12px;
    border-top: 2px solid var(--line);
}

.factor-prime {
    color: var(--green, #417000);
    font-size: .82rem;
    font-weight: 700;
}

.page-byline {
    display: flex;
    flex-wrap: wrap;
    gap: 6px 18px;
    margin: 10px 0 8px;
    color: #60717c;
    font-size: .86rem;
}

.page-byline span + span::before {
    content: "•";
    margin-right: 18px;
    color: #91a0a9;
}

.on-page-nav {
    width: min(100% - 40px, 1180px);
    margin: 4px 0 24px 0;
    padding: 16px 18px;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: #f7fafb;
}

.on-page-nav strong {
    display: block;
    margin-bottom: 8px;
    color: var(--blue);
}

.on-page-nav div {
    display: flex;
    flex-wrap: wrap;
    gap: 7px 18px;
}

.on-page-nav a {
    color: var(--blue);
    font-size: .9rem;
    text-underline-offset: 3px;
}

h2[id] {
    scroll-margin-top: 20px;
}

.network-input-pair {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(120px, .55fr);
    gap: 10px;
}

.suffixed-input {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
}

.suffixed-input span {
    padding: 0 4px 12px 10px;
    font-weight: 700;
}

@media (max-width: 780px) {
    .grid {
        grid-template-columns: 1fr;
    }

    .intro {
        min-height: 0;
    }

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

    .proportion-layout {
        gap: 10px;
    }

    .fraction-calculation {
        gap: 10px;
    }

    .mixed-number-inputs {
        grid-template-columns: 1fr;
    }

    .weight-row {
        grid-template-columns: 1fr 1fr;
    }

    .page-byline {
        display: block;
    }

    .page-byline span {
        display: block;
    }

    .page-byline span + span::before {
        content: none;
    }

    .on-page-nav {
        width: min(100% - 30px, 1180px);
        margin-bottom: 18px;
    }

    .on-page-nav div {
        display: grid;
        gap: 7px;
    }

    .network-input-pair {
        grid-template-columns: 1fr;
        gap: 0;
    }
}