:root {
    --bg-color: #f5f8fb;
    --card-bg: #ffffff;
    --text-color: #243242;
    --muted-color: #657284;
    --accent-color: #0b83d8;
    --accent-dark: #062b54;
    --border-color: #d9e2ec;
    --table-header: #062b54;
    --font-main: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
}

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

body {
    background: var(--bg-color);
    color: var(--text-color);
    font-family: var(--font-main);
    line-height: 1.6;
}

header {
    position: sticky;
    top: 0;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    padding: 12px 5%;
    background: #fff;
    border-bottom: 1px solid var(--border-color);
}

.logo {
    display: flex;
    align-items: center;
    gap: 16px;
    color: var(--accent-dark);
    font-weight: 900;
    letter-spacing: .04em;
    text-decoration: none;
}

.logo:hover,
.logo:focus-visible {
    opacity: .86;
    outline: none;
}

.logo img {
    width: 310px;
    height: 58px;
    object-fit: contain;
    background: transparent;
    border-radius: 0;
}

.logo small {
    display: block;
    color: var(--muted-color);
    font-size: .72rem;
    letter-spacing: .12em;
}

.back-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    min-height: 44px;
    padding: 0 16px;
    color: var(--accent-dark);
    border: 1px solid var(--accent-color);
    border-radius: 4px;
    font-weight: 800;
    text-decoration: none;
    transition: background .2s ease, color .2s ease;
}

.back-btn:hover {
    background: var(--accent-color);
    color: #fff;
}

.container {
    display: grid;
    grid-template-columns: 250px 1fr;
    gap: 40px;
    max-width: 1200px;
    margin: 40px auto;
    padding: 0 20px;
}

.sidebar {
    position: sticky;
    top: 104px;
    height: fit-content;
    padding: 20px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    box-shadow: 0 12px 36px rgba(7, 17, 29, .06);
}

.sidebar h3 {
    margin-bottom: 15px;
    padding-bottom: 10px;
    color: var(--accent-color);
    border-bottom: 1px solid var(--border-color);
}

.sidebar ul {
    list-style: none;
}

.sidebar li {
    margin-bottom: 10px;
}

.sidebar a {
    display: block;
    color: var(--muted-color);
    text-decoration: none;
    transition: color .2s ease, padding-left .2s ease, border-color .2s ease;
}

.sidebar a:hover,
.sidebar a.active {
    padding-left: 5px;
    color: var(--accent-dark);
    border-left: 3px solid var(--accent-color);
}

.content section {
    margin-bottom: 60px;
    padding: 30px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    box-shadow: 0 16px 48px rgba(7, 17, 29, .07);
}

h1 {
    margin-bottom: 10px;
    color: #07111d;
    font-size: 2.5rem;
}

h2 {
    margin: 0 0 20px;
    padding-bottom: 10px;
    color: var(--accent-color);
    border-bottom: 1px solid var(--border-color);
    font-size: 1.8rem;
}

h3 {
    margin: 25px 0 15px;
    color: #07111d;
    font-size: 1.3rem;
}

p {
    margin-bottom: 15px;
    color: #445568;
    text-align: justify;
}

ul.specs-list {
    margin: 0 0 20px 20px;
    color: #445568;
}

ul.specs-list li {
    margin-bottom: 8px;
}

.table-wrapper {
    overflow-x: auto;
    margin: 20px 0;
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: 8px;
}

table {
    width: 100%;
    min-width: 800px;
    border-collapse: collapse;
    font-size: .9rem;
}

th {
    padding: 12px;
    background: var(--table-header);
    color: #fff;
    font-weight: 800;
    text-align: center;
    text-transform: uppercase;
}

td {
    padding: 10px;
    color: #344558;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}

tr:nth-child(even) {
    background: #f8fafc;
}

tr:hover {
    background: #eaf5ff;
}

.diagram-placeholder {
    margin: 20px 0;
    padding: 40px;
    color: #60768a;
    text-align: center;
    background: #eef5fb;
    border: 1px dashed #8dbfe4;
    border-radius: 8px;
}

footer {
    margin-top: 50px;
    padding: 40px;
    background: var(--accent-dark);
    color: #dceaf6;
    text-align: center;
    border-top: 1px solid var(--accent-color);
}

footer p {
    color: #dceaf6;
    text-align: center;
}

.mobile-quote-bar {
    display: none;
}

@media (max-width: 900px) {
    .container {
        grid-template-columns: 1fr;
    }

    .sidebar {
        display: none;
    }
}

@media (max-width: 640px) {
    body {
        padding-bottom: 76px;
    }

    header {
        gap: 12px;
        padding: 10px 14px;
    }

    .logo {
        max-width: calc(100% - 120px);
        gap: 8px;
    }

    .logo img {
        width: 210px;
        height: 48px;
    }

    .logo small {
        display: none;
    }

    .back-btn {
        min-height: 40px;
        padding: 0 10px;
        font-size: .82rem;
        white-space: nowrap;
    }

    .content section {
        padding: 22px;
    }

    h1 {
        font-size: 2rem;
    }

    .mobile-quote-bar {
        position: fixed;
        left: 0;
        right: 0;
        bottom: 0;
        z-index: 1200;
        display: block;
        padding: 10px 14px;
        background: rgba(255, 255, 255, .96);
        border-top: 1px solid var(--border-color);
        box-shadow: 0 -12px 30px rgba(7, 17, 29, .12);
    }

    .mobile-quote-bar a {
        display: flex;
        align-items: center;
        justify-content: center;
        gap: 10px;
        min-height: 50px;
        border-radius: 6px;
        background: #25d366;
        color: #fff;
        font-weight: 900;
        letter-spacing: .03em;
        text-decoration: none;
        text-transform: uppercase;
    }
}