/* ============================================================
   style.css — calculateur-tva.com
   Mobile-first, vanilla CSS, BEM naming, CSS custom properties
   ============================================================ */

/* ── Variables ─────────────────────────────────────────────── */
:root {
    --color-primary:      #1a3a5c;
    --color-secondary:    #2e6da4;
    --color-accent:       #e8f4fd;
    --color-success:      #2e7d32;
    --color-text:         #1a1a2e;
    --color-text-light:   #555566;
    --color-border:       #d0dcea;
    --color-bg:           #ffffff;
    --color-bg-alt:       #f7f9fc;
    --color-highlight:    #fff8e1;

    --font-body: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
    --font-mono: "Courier New", Courier, monospace;
    --font-size-base: 16px;
    --line-height: 1.65;

    --space-xs:  0.25rem;
    --space-sm:  0.5rem;
    --space-md:  1rem;
    --space-lg:  1.5rem;
    --space-xl:  2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;

    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;

    --shadow-sm: 0 1px 3px rgba(0,0,0,.08);
    --shadow-md: 0 4px 12px rgba(0,0,0,.12);
    --shadow-lg: 0 8px 24px rgba(0,0,0,.15);

    --max-width: 1200px;
    --header-height: 64px;
}

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

html {
    font-size: var(--font-size-base);
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    font-size: 1rem;
    line-height: var(--line-height);
    color: var(--color-text);
    background: var(--color-bg);
    -webkit-font-smoothing: antialiased;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: var(--color-secondary);
    text-decoration: underline;
}

a:hover {
    text-decoration: none;
}

h1, h2, h3, h4 {
    font-weight: 700;
    line-height: 1.3;
    color: var(--color-primary);
}

h1 {
    font-size: clamp(1.5rem, 4vw, 2.2rem);
    margin-bottom: var(--space-md);
}

h2 {
    font-size: clamp(1.2rem, 3vw, 1.7rem);
    margin-bottom: var(--space-md);
    margin-top: var(--space-2xl);
}

h3 {
    font-size: 1.15rem;
    margin-bottom: var(--space-sm);
    margin-top: var(--space-xl);
}

p {
    margin-bottom: var(--space-md);
}

ul, ol {
    padding-left: 1.5rem;
    margin-bottom: var(--space-md);
}

li {
    margin-bottom: var(--space-xs);
}

strong {
    font-weight: 700;
}

em {
    font-style: italic;
}

/* ── Container ─────────────────────────────────────────────── */
.container {
    width: 100%;
    max-width: var(--max-width);
    margin-inline: auto;
    padding-inline: var(--space-md);
}

@media (min-width: 768px) {
    .container {
        padding-inline: var(--space-xl);
    }
}

/* ── Skip link ─────────────────────────────────────────────── */
.skip-link {
    position: absolute;
    top: -9999px;
    left: var(--space-md);
    padding: var(--space-sm) var(--space-md);
    background: var(--color-primary);
    color: #fff;
    border-radius: var(--radius-sm);
    z-index: 1000;
    text-decoration: none;
    font-weight: 600;
}

.skip-link:focus {
    top: var(--space-sm);
}

/* ── Header / Navigation ────────────────────────────────────── */
.site-header {
    background: var(--color-primary);
    height: var(--header-height);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-md);
}

.site-header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.site-logo {
    display: flex;
    align-items: center;
    flex-shrink: 0;
    text-decoration: none;
}

.site-logo img {
    height: 32px;
    width: auto;
}

/* Hamburger button */
.nav-toggle {
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 40px;
    height: 40px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
    border-radius: var(--radius-sm);
    flex-shrink: 0;
}

.nav-toggle__bar {
    display: block;
    height: 2px;
    background: #fff;
    border-radius: 2px;
    transition: transform .25s, opacity .25s;
}

.nav-toggle.is-open .nav-toggle__bar:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.nav-toggle.is-open .nav-toggle__bar:nth-child(2) {
    opacity: 0;
}

.nav-toggle.is-open .nav-toggle__bar:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* Nav mobile : masquée par défaut */
.main-nav {
    display: none;
    position: fixed;
    inset: var(--header-height) 0 0 0;
    background: var(--color-primary);
    padding: var(--space-lg);
    overflow-y: auto;
    z-index: 99;
}

.main-nav.is-open {
    display: block;
}

.main-nav__list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.main-nav__item {
    border-bottom: 1px solid rgba(255,255,255,.1);
}

.main-nav__link {
    display: block;
    padding: var(--space-md) 0;
    color: #fff;
    text-decoration: none;
    font-weight: 500;
}

.main-nav__link:hover {
    color: var(--color-accent);
    text-decoration: none;
}

/* Dropdown mobile : visible en dessous du lien parent */
.main-nav__dropdown {
    list-style: none;
    padding-left: var(--space-md);
    margin: 0 0 var(--space-sm);
    border-left: 2px solid rgba(255,255,255,.2);
}

.main-nav__dropdown li {
    margin-bottom: 0;
}

.main-nav__dropdown a {
    display: block;
    padding: var(--space-sm) 0;
    color: rgba(255,255,255,.8);
    text-decoration: none;
    font-size: 0.9rem;
}

.main-nav__dropdown a:hover {
    color: #fff;
}

/* Desktop nav */
@media (min-width: 1024px) {
    .nav-toggle {
        display: none;
    }

    .main-nav {
        display: flex !important;
        position: static;
        background: transparent;
        padding: 0;
        overflow: visible;
    }

    .main-nav__list {
        display: flex;
        align-items: center;
    }

    .main-nav__item {
        border-bottom: none;
        position: relative;
    }

    .main-nav__link {
        padding: var(--space-sm) var(--space-md);
        border-radius: var(--radius-sm);
        font-size: 0.9rem;
        white-space: nowrap;
    }

    .main-nav__link:hover {
        background: rgba(255,255,255,.1);
    }

    /* Dropdown desktop : caché, apparaît au hover */
    .main-nav__dropdown {
        display: none;
        position: absolute;
        top: calc(100% + 2px);
        left: 0;
        min-width: 230px;
        background: #fff;
        border-radius: var(--radius-md);
        box-shadow: var(--shadow-lg);
        padding: var(--space-sm) 0;
        border: 1px solid var(--color-border);
        border-left: 1px solid var(--color-border);
        padding-left: 0;
        margin: 0;
        z-index: 101;
    }

    .main-nav__item--dropdown:hover .main-nav__dropdown {
        display: block;
    }

    .main-nav__dropdown a {
        color: var(--color-text);
        padding: var(--space-sm) var(--space-md);
        font-size: 0.9rem;
    }

    .main-nav__dropdown a:hover {
        background: var(--color-bg-alt);
        color: var(--color-secondary);
    }
}

/* ── Breadcrumb ─────────────────────────────────────────────── */
.breadcrumb {
    background: var(--color-bg-alt);
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-sm) 0;
    font-size: 0.85rem;
}

.breadcrumb__list {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-xs);
    list-style: none;
    padding: 0;
    margin: 0;
    align-items: center;
}

.breadcrumb__item {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
    color: var(--color-text-light);
}

.breadcrumb__item:not(:last-child)::after {
    content: '›';
    color: var(--color-text-light);
}

.breadcrumb__item a {
    color: var(--color-secondary);
    text-decoration: none;
}

.breadcrumb__item a:hover {
    text-decoration: underline;
}

.breadcrumb__item:last-child {
    color: var(--color-text);
    font-weight: 500;
}

/* ── Hero sections ──────────────────────────────────────────── */
.hero {
    background: linear-gradient(135deg, var(--color-primary) 0%, #243d5c 100%);
    color: #fff;
    padding: var(--space-2xl) 0;
}

.hero__inner {
    display: flex;
    flex-direction: column;
    gap: var(--space-xl);
    align-items: flex-start;
}

.hero h1 {
    color: #fff;
    margin-bottom: var(--space-md);
}

.lead {
    font-size: 1.1rem;
    line-height: 1.7;
    color: rgba(255,255,255,.9);
    margin-bottom: 0;
}

.hero--article {
    padding: var(--space-xl) 0;
}

.hero--article .lead {
    font-size: 1rem;
}

.hero__image {
    display: none;
}

@media (min-width: 768px) {
    .hero__inner {
        flex-direction: row;
        align-items: center;
    }

    .hero__text {
        flex: 1;
    }

    .hero__image {
        display: block;
        flex-shrink: 0;
    }
}

/* Data update badge */
.data-update {
    font-size: 0.85rem;
    color: rgba(255,255,255,.75);
    margin-top: var(--space-sm);
    margin-bottom: 0;
}

.data-update__badge {
    display: inline-block;
    background: rgba(255,255,255,.15);
    border-radius: var(--radius-sm);
    padding: 2px var(--space-sm);
    margin-right: var(--space-sm);
    font-weight: 600;
}

/* ── Summary box (featured snippet) ────────────────────────── */
.summary-section {
    padding: var(--space-xl) 0;
    background: var(--color-accent);
    border-bottom: 1px solid var(--color-border);
}

.summary-box {
    background: #fff;
    border: 2px solid var(--color-secondary);
    border-radius: var(--radius-lg);
    padding: var(--space-xl);
    max-width: 700px;
}

.summary-box__title {
    font-size: 1.1rem;
    color: var(--color-primary);
    margin-bottom: var(--space-md);
    margin-top: 0;
}

.summary-box__list {
    list-style: none;
    padding: 0;
    margin: 0 0 var(--space-md);
}

.summary-box__list li {
    padding: var(--space-sm) 0;
    border-bottom: 1px solid var(--color-border);
    font-size: 1rem;
}

.summary-box__list li:last-child {
    border-bottom: none;
}

/* ── Content sections ───────────────────────────────────────── */
.content-section {
    padding: var(--space-2xl) 0;
}

.data-section {
    padding: var(--space-2xl) 0;
}

.content-article h2:first-of-type {
    margin-top: 0;
}

/* Formula box */
.formula-box {
    background: var(--color-bg-alt);
    border-left: 4px solid var(--color-secondary);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    padding: var(--space-lg);
    margin: var(--space-lg) 0;
    font-family: var(--font-mono);
    font-size: 0.95rem;
}

.formula-box p,
.formula-box ul {
    margin-bottom: var(--space-sm);
    font-family: var(--font-body);
}

.formula-box p:last-child {
    margin-bottom: 0;
}

.formula-list {
    padding-left: 0;
    list-style: none;
}

.formula-list li {
    padding: var(--space-sm) 0;
    border-bottom: 1px dashed var(--color-border);
}

.formula-list li:last-child {
    border-bottom: none;
}

/* Data table */
.table-responsive {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    margin: var(--space-md) 0;
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.95rem;
}

.data-table th,
.data-table td {
    padding: var(--space-sm) var(--space-md);
    text-align: left;
    border: 1px solid var(--color-border);
}

.data-table thead {
    background: var(--color-primary);
}

.data-table thead th {
    color: #fff;
    font-weight: 600;
}

.data-table tbody tr:nth-child(even) {
    background: var(--color-bg-alt);
}

.data-table tbody tr:hover {
    background: var(--color-accent);
}

/* Rate cells */
.rate {
    font-weight: 700;
    white-space: nowrap;
}

.rate--normal       { color: var(--color-primary); }
.rate--intermediate { color: #b71c1c; }
.rate--reduced      { color: var(--color-success); }
.rate--super-reduced { color: #6a1a7a; }

/* ── FAQ section ────────────────────────────────────────────── */
.faq-section {
    padding: var(--space-2xl) 0;
    background: var(--color-bg-alt);
}

.faq-list {
    margin-top: var(--space-lg);
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.faq-item {
    background: #fff;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.faq-item__question {
    display: block;
    padding: var(--space-md) var(--space-lg);
    font-weight: 600;
    cursor: pointer;
    list-style: none;
    position: relative;
    padding-right: 3rem;
    color: var(--color-primary);
    font-size: 1rem;
}

.faq-item__question::-webkit-details-marker {
    display: none;
}

.faq-item__question::after {
    content: '+';
    position: absolute;
    right: var(--space-lg);
    top: 50%;
    transform: translateY(-50%);
    font-size: 1.25rem;
    font-weight: 300;
    color: var(--color-secondary);
    line-height: 1;
}

.faq-item[open] .faq-item__question::after {
    content: '−';
}

.faq-item__answer {
    padding: var(--space-md) var(--space-lg) var(--space-md);
    border-top: 1px solid var(--color-border);
}

.faq-item__answer p:last-child {
    margin-bottom: 0;
}

/* ── Related links section ──────────────────────────────────── */
.related-section {
    padding: var(--space-2xl) 0;
}

.related-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: var(--space-md);
    margin-top: var(--space-lg);
}

.related-card {
    display: block;
    padding: var(--space-md) var(--space-lg);
    background: var(--color-bg-alt);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    text-decoration: none;
    color: var(--color-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    transition: background .15s, border-color .15s, transform .15s;
}

.related-card:hover {
    background: var(--color-accent);
    border-color: var(--color-secondary);
    transform: translateY(-2px);
    text-decoration: none;
}

/* ── Buttons ────────────────────────────────────────────────── */
.btn-primary {
    display: inline-block;
    padding: var(--space-sm) var(--space-xl);
    background: var(--color-secondary);
    color: #fff;
    text-decoration: none;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 1rem;
    transition: background .15s, transform .15s;
    border: none;
    cursor: pointer;
    margin-top: var(--space-md);
}

.btn-primary:hover {
    background: #245f8f;
    color: #fff;
    text-decoration: none;
    transform: translateY(-1px);
}

.btn-primary.btn--large {
    padding: var(--space-md) var(--space-2xl);
    font-size: 1.1rem;
}

.btn-secondary {
    display: inline-block;
    padding: var(--space-sm) var(--space-xl);
    background: transparent;
    color: var(--color-secondary);
    border: 2px solid var(--color-secondary);
    text-decoration: none;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 1rem;
    transition: background .15s, color .15s;
    cursor: pointer;
    margin-top: var(--space-md);
}

.btn-secondary:hover {
    background: var(--color-secondary);
    color: #fff;
    text-decoration: none;
}

/* ── Tool CTA box ───────────────────────────────────────────── */
.tool-cta-section {
    padding: var(--space-2xl) 0;
    background: var(--color-accent);
}

.tool-cta-box {
    text-align: center;
    padding: var(--space-2xl);
    background: #fff;
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border);
    box-shadow: var(--shadow-sm);
    max-width: 600px;
    margin: 0 auto;
}

.tool-cta-box h2 {
    margin-top: 0;
}

.tool-cta-box p {
    color: var(--color-text-light);
    margin-bottom: 0;
}

/* ── Partner section ────────────────────────────────────────── */
.partner-section {
    padding: var(--space-2xl) 0;
    background: var(--color-highlight);
    border-top: 3px solid #f0a500;
    border-bottom: 3px solid #f0a500;
}

.partner-box {
    max-width: 640px;
}

.partner-box h2 {
    margin-top: 0;
    color: var(--color-primary);
}

/* ── Footer ─────────────────────────────────────────────────── */
.site-footer {
    background: var(--color-primary);
    color: rgba(255,255,255,.85);
    padding: var(--space-2xl) 0 var(--space-md);
    margin-top: var(--space-2xl);
}

.site-footer__grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-xl);
    margin-bottom: var(--space-xl);
}

@media (min-width: 600px) {
    .site-footer__grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 1024px) {
    .site-footer__grid {
        grid-template-columns: 2fr 1fr 1fr 1fr;
    }
}

.site-footer__col--brand .site-footer__baseline {
    font-size: 0.85rem;
    margin-top: var(--space-md);
    color: rgba(255,255,255,.65);
    line-height: 1.5;
    margin-bottom: 0;
}

.site-footer__heading {
    font-size: 0.8rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: .08em;
    color: rgba(255,255,255,.45);
    margin-bottom: var(--space-md);
    margin-top: 0;
}

.site-footer__links {
    list-style: none;
    padding: 0;
    margin: 0;
}

.site-footer__links li {
    margin-bottom: var(--space-sm);
}

.site-footer__links a {
    color: rgba(255,255,255,.75);
    text-decoration: none;
    font-size: 0.9rem;
}

.site-footer__links a:hover {
    color: #fff;
    text-decoration: underline;
}

.site-footer__bottom {
    padding-top: var(--space-md);
    border-top: 1px solid rgba(255,255,255,.1);
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
    font-size: 0.85rem;
    color: rgba(255,255,255,.45);
}

@media (min-width: 768px) {
    .site-footer__bottom {
        flex-direction: row;
        justify-content: space-between;
        align-items: center;
    }
}

.site-footer__bottom nav {
    display: flex;
    gap: var(--space-md);
    flex-wrap: wrap;
}

.site-footer__bottom a {
    color: rgba(255,255,255,.45);
    text-decoration: none;
}

.site-footer__bottom a:hover {
    color: rgba(255,255,255,.8);
    text-decoration: underline;
}

/* ── Utility ─────────────────────────────────────────────────── */
.visually-hidden {
    clip: rect(0 0 0 0);
    clip-path: inset(50%);
    height: 1px;
    overflow: hidden;
    position: absolute;
    white-space: nowrap;
    width: 1px;
}

.text-center { text-align: center; }
.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }

/* ── Charts ──────────────────────────────────────────────────── */
.chart-container {
    position: relative;
    margin: var(--space-xl) 0;
    background: var(--color-bg-alt);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--space-lg);
}

.chart-container--tall {
    height: 420px;
}

.chart-container canvas {
    max-width: 100%;
}