/* === Reset & Base === */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    /* Colors */
    --color-primary: #1a2b5f;
    --color-accent: #e67e22;
    --color-text: #333;
    --color-text-light: #666;
    --color-bg: #fff;
    --color-bg-light: #f5f6fa;
    --color-border: #e8e9ed;

    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.25rem;
    --text-xl: 1.75rem;
    --text-2xl: 2rem;

    /* Spacing — 4px base rhythm */
    --space-1: 0.25rem;   /* 4px */
    --space-2: 0.5rem;    /* 8px */
    --space-3: 0.75rem;   /* 12px */
    --space-4: 1rem;      /* 16px */
    --space-6: 1.5rem;    /* 24px */
    --space-8: 2rem;      /* 32px */
    --space-12: 3rem;     /* 48px */

    /* Layout */
    --max-width: 1100px;
    --radius: 6px;
    --radius-lg: 8px;
}

body {
    font-family: var(--font-family);
    color: var(--color-text);
    background: var(--color-bg);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

a {
    text-decoration: none;
    color: inherit;
}

/* === Visually Hidden === */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* === Header === */
.site-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-3) var(--space-8);
    border-bottom: 1px solid var(--color-border);
    background: var(--color-bg);
}

.site-header__left {
    display: flex;
    align-items: center;
    gap: var(--space-4);
}

.site-header__logo {
    font-size: var(--text-lg);
    font-weight: 800;
    color: var(--color-primary);
    letter-spacing: -0.5px;
    text-transform: uppercase;
}

.site-header__logo span {
    color: var(--color-accent);
}

.site-header__breadcrumb {
    font-size: var(--text-xs);
    color: var(--color-text-light);
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.site-header__breadcrumb svg {
    width: 18px;
    height: 18px;
    color: var(--color-text-light);
}

.site-header__breadcrumb a {
    color: var(--color-text-light);
    transition: color 0.15s;
}

.site-header__breadcrumb a:hover {
    color: var(--color-primary);
}

.site-header__breadcrumb-sep {
    display: flex;
    align-items: center;
    color: var(--color-accent);
}

.site-header__breadcrumb-sep svg {
    width: 14px;
    height: 14px;
    color: var(--color-accent);
}

.site-header__right {
    display: flex;
    align-items: center;
    gap: var(--space-6);
}

.site-header__link {
    display: flex;
    align-items: center;
    gap: var(--space-1);
    font-size: var(--text-xs);
    font-weight: 600;
    text-transform: uppercase;
    color: var(--color-primary);
    letter-spacing: 0.5px;
}

.site-header__link svg {
    width: 18px;
    height: 18px;
}

/* === Search Hero === */
.search-hero {
    background: var(--color-bg-light);
    padding: var(--space-12) var(--space-8) var(--space-8);
    text-align: center;
}

.search-hero__content {
    max-width: 600px;
    margin: 0 auto var(--space-6);
}

.search-hero__eyebrow {
    display: none;
}

.search-hero__content h1 {
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--space-2);
}

.search-hero__content h1::after {
    content: '.';
    color: var(--color-accent);
}

.search-hero__content p {
    font-size: var(--text-sm);
    color: var(--color-text-light);
    line-height: 1.6;
}

.search-hero__form {
    max-width: 500px;
    margin: 0 auto;
    position: relative;
}

.search-hero__form input[type="search"] {
    width: 100%;
    padding: var(--space-3) var(--space-4);
    padding-right: var(--space-8);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    font-size: var(--text-sm);
    background: var(--color-bg);
    outline: none;
    transition: border-color 0.2s;
}

.search-hero__form input[type="search"]:focus {
    border-color: var(--color-primary);
}

.search-hero__form::after {
    content: '';
    position: absolute;
    right: var(--space-4);
    top: 50%;
    transform: translateY(-50%);
    width: 18px;
    height: 18px;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%23999' stroke-width='2'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' d='m21 21-5.197-5.197m0 0A7.5 7.5 0 1 0 5.196 5.196a7.5 7.5 0 0 0 10.607 10.607Z'/%3E%3C/svg%3E");
    background-size: contain;
    pointer-events: none;
}

/* === Main Content === */
main {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--space-8);
    width: 100%;
    flex: 1;
}

main > h2 {
    text-align: center;
    font-size: var(--text-lg);
    font-weight: 700;
    color: var(--color-primary);
    margin: var(--space-8) 0 var(--space-4);
    padding-bottom: var(--space-3);
    border-bottom: 2px solid var(--color-primary);
    display: inline-block;
    width: 100%;
}

/* === Category Grid === */
.category-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-4);
    margin-bottom: var(--space-4);
}

.category-grid__item {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: var(--space-6) var(--space-4);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    transition: box-shadow 0.2s, border-color 0.2s;
    gap: var(--space-3);
}

.category-grid__item:hover {
    border-color: var(--color-primary);
    box-shadow: 0 2px 12px rgba(26, 43, 95, 0.08);
}

.category-grid__item svg {
    width: 36px;
    height: 36px;
    color: var(--color-primary);
}

.category-grid__label {
    font-size: var(--text-xs);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--color-primary);
}

.category-grid__label::after {
    content: ' ›';
    color: var(--color-accent);
    font-weight: 700;
}

/* === Footer === */
.site-footer {
    border-top: 1px solid var(--color-border);
    padding: var(--space-4) var(--space-8);
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: var(--text-xs);
    color: var(--color-text-light);
    margin-top: auto;
}

.site-footer__logo {
    font-size: var(--text-base);
    font-weight: 800;
    color: var(--color-primary);
    text-transform: uppercase;
}

.site-footer__logo span {
    color: var(--color-accent);
}

.site-footer__right {
    display: flex;
    align-items: center;
    gap: var(--space-6);
}

.site-footer__right a {
    color: var(--color-accent);
}

.site-footer__right a:hover {
    text-decoration: underline;
}

/* === Article Hero === */
.article-hero {
    background: linear-gradient(135deg, var(--color-bg-light) 0%, #e8eaf0 100%);
    padding: var(--space-8);
}

.article-hero__inner {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    align-items: center;
    gap: var(--space-6);
}

.article-hero__back {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--color-bg);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    color: var(--color-primary);
    transition: box-shadow 0.2s;
    flex-shrink: 0;
}

.article-hero__back:hover {
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.12);
}

.article-hero h1 {
    font-size: var(--text-2xl);
    font-weight: 700;
    color: var(--color-primary);
}

.article-hero h1::after {
    content: '.';
    color: var(--color-accent);
}

/* === Article Layout === */
.article-layout {
    max-width: var(--max-width);
    width: 100%;
    margin: 0 auto;
    padding: var(--space-8);
    display: grid;
    grid-template-columns: 260px 1fr;
    gap: var(--space-8);
    flex: 1;
}

.article-layout .article-main {
    padding: 0;
    margin: 0;
    max-width: none;
    min-width: 0;
}

/* === Article Sidebar === */
.sidebar__title {
    font-size: var(--text-sm);
    font-weight: 700;
    color: var(--color-accent);
    margin-bottom: var(--space-4);
    padding-bottom: var(--space-3);
    border-bottom: 1px solid var(--color-border);
}

.sidebar__nav {
    display: flex;
    flex-direction: column;
}

.sidebar-group__details {
    border-bottom: 1px solid var(--color-border);
}

.sidebar-group__summary {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-3) 0;
    cursor: pointer;
    list-style: none;
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-text);
}

.sidebar-group__summary::-webkit-details-marker {
    display: none;
}

.sidebar-group__summary::marker {
    display: none;
    content: '';
}

.sidebar-group__chevron {
    width: 16px;
    height: 16px;
    color: var(--color-text-light);
    transition: transform 0.2s;
    flex-shrink: 0;
}

.sidebar-group__details[open] .sidebar-group__chevron {
    transform: rotate(90deg);
}

.sidebar-group__list {
    list-style: none;
    padding: 0 0 var(--space-3) var(--space-4);
}

.sidebar-group__item {
    padding: var(--space-1) 0;
    font-size: var(--text-xs);
    color: var(--color-text-light);
}

.sidebar-group__item a {
    color: var(--color-text-light);
    transition: color 0.15s;
}

.sidebar-group__item a:hover {
    color: var(--color-primary);
}

.sidebar-group__item--active {
    color: var(--color-primary);
    font-weight: 600;
}

/* === Article Content === */
.article-content {
    position: relative;
}

.article-content__actions {
    display: flex;
    gap: var(--space-2);
    justify-content: flex-end;
    margin-bottom: var(--space-2);
}

.article-content__action {
    display: flex;
    align-items: center;
    justify-content: center;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--color-text-light);
    padding: var(--space-1);
    border-radius: 4px;
    transition: color 0.15s;
}

.article-content__action:hover {
    color: var(--color-primary);
}

.article-content h2 {
    font-size: var(--text-lg);
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--space-4);
}

.article-content__body {
    font-size: var(--text-sm);
    line-height: 1.7;
    color: var(--color-text);
    margin-bottom: var(--space-6);
}

.article-content__body p {
    margin-bottom: var(--space-4);
}

.article-content__body h2 {
    font-size: var(--text-base);
    font-weight: 700;
    color: var(--color-primary);
    margin: var(--space-6) 0 var(--space-2);
}

.article-content__body h3 {
    font-size: var(--text-sm);
    font-weight: 700;
    color: var(--color-accent);
    margin: var(--space-6) 0 var(--space-2);
}

.article-content__body h4 {
    font-size: var(--text-sm);
    font-weight: 700;
    color: var(--color-text);
    margin: var(--space-4) 0 var(--space-2);
}

.article-content__body a {
    color: var(--color-accent);
    text-decoration: underline;
}

.article-content__body a:hover {
    color: var(--color-primary);
}

.article-content__body strong,
.article-content__body b {
    font-weight: 700;
    color: var(--color-text);
}

.article-content__body ol,
.article-content__body ul {
    margin: var(--space-2) 0 var(--space-4) var(--space-6);
}

.article-content__body li {
    margin-bottom: var(--space-1);
}

.article-content__body blockquote {
    border-left: 3px solid var(--color-accent);
    margin: var(--space-4) 0;
    padding: var(--space-3) var(--space-4);
    background: var(--color-bg-light);
    border-radius: 0 var(--radius) var(--radius) 0;
    font-size: var(--text-sm);
    color: var(--color-text-light);
}

.article-content__body img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius);
    margin: var(--space-4) 0;
}

.article-content__body pre {
    white-space: pre-wrap;
    word-wrap: break-word;
    overflow-wrap: break-word;
    margin: var(--space-4) 0;
    padding: var(--space-3) var(--space-4);
    background: var(--color-bg-light);
    border-radius: var(--radius);
    font-size: var(--text-sm);
}

.article-content__body code {
    background: var(--color-bg-light);
    padding: var(--space-1) var(--space-2);
    border-radius: 3px;
    font-size: 0.85em;
}

.article-content__body figure {
    margin: var(--space-4) 0;
}

.article-content__body table {
    width: 100%;
    border-collapse: collapse;
    margin: var(--space-4) 0;
    font-size: var(--text-sm);
}

.article-content__body th,
.article-content__body td {
    padding: var(--space-2) var(--space-3);
    border: 1px solid var(--color-border);
    text-align: left;
}

.article-content__body th {
    background: var(--color-bg-light);
    font-weight: 700;
    color: var(--color-primary);
}

.article-content__back {
    display: inline-flex;
    align-items: center;
    gap: var(--space-1);
    font-size: var(--text-sm);
    color: var(--color-primary);
    font-weight: 500;
    margin-bottom: var(--space-8);
    padding: var(--space-2) 0;
}

.article-content__back:hover {
    text-decoration: underline;
}

.article-content__back svg {
    color: var(--color-accent);
}

/* === Article Nav (prev/next) === */
.article-nav {
    display: flex;
    justify-content: space-between;
    align-items: stretch;
    gap: var(--space-4);
    margin-bottom: var(--space-6);
}

.article-nav__link {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    font-size: var(--text-xs);
    color: var(--color-accent);
    font-weight: 500;
    max-width: 48%;
    transition: color 0.15s;
}

.article-nav__link:hover {
    color: var(--color-primary);
}

.article-nav__link svg {
    flex-shrink: 0;
}

.article-nav__link--next {
    margin-left: auto;
    text-align: right;
}

/* === Article Feedback === */
.article-content__feedback {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    padding-top: var(--space-4);
    border-top: 1px solid var(--color-border);
    font-size: var(--text-sm);
    color: var(--color-text-light);
}

.article-content__feedback-sep {
    width: 1px;
    height: 20px;
    background: var(--color-border);
    margin: 0 var(--space-2);
}

/* === Responsive === */
@media (max-width: 768px) {
    .category-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .site-header {
        padding: var(--space-3) var(--space-4);
    }

    .search-hero {
        padding: var(--space-8) var(--space-4);
    }

    main {
        padding: var(--space-4);
    }

    .article-layout {
        grid-template-columns: 1fr;
        padding: var(--space-4);
    }

    .article-hero {
        padding: var(--space-6) var(--space-4);
    }

    .article-hero h1 {
        font-size: var(--text-xl);
    }

    .site-footer {
        padding: var(--space-4);
        flex-direction: column;
        gap: var(--space-2);
    }
}

@media (max-width: 480px) {
    .category-grid {
        grid-template-columns: 1fr;
    }

    .article-nav {
        flex-direction: column;
    }

    .article-nav__link {
        max-width: 100%;
    }
}