:root {
    --color-background: #05070f;
    --color-background-alt: rgba(12, 19, 35, 0.9);
    --color-surface: rgba(18, 28, 48, 0.85);
    --color-surface-strong: rgba(8, 14, 26, 0.95);
    --color-border: rgba(148, 163, 184, 0.24);
    --color-border-strong: rgba(94, 234, 212, 0.4);
    --color-text: #f5f7ff;
    --color-text-muted: #b6c3e1;
    --color-accent: #5eead4;
    --color-accent-strong: #22d3ee;
    --color-danger: #f87171;
    --shadow-lg: 0 30px 60px rgba(2, 6, 23, 0.55);
    --shadow-md: 0 18px 36px rgba(2, 6, 23, 0.4);
    --radius-sm: 10px;
    --radius-md: 14px;
    --radius-lg: 20px;
    /* Largeur moderne et fluide : min 320px, 95% de l’écran, max 1600px */
    --max-width: clamp(320px, 95vw, 1600px);
    --transition-fast: 150ms ease;
    font-family: 'Inter', 'Segoe UI', 'Roboto', sans-serif;
}

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

body {
    margin: 0;
    font-family: 'Inter', 'Segoe UI', 'Roboto', sans-serif;
    color: var(--color-text);
    line-height: 1.6;
    background:
        radial-gradient(circle at top left, rgba(94, 234, 212, 0.12), transparent 55%),
        radial-gradient(circle at bottom right, rgba(34, 211, 238, 0.14), transparent 58%),
        linear-gradient(180deg, rgba(7, 10, 20, 0.95), rgba(5, 7, 15, 1)),
        var(--color-background);
    min-height: 100vh;
    position: relative;
}

body::before {
    content: '';
    position: fixed;
    inset: 0;
    background: url('../img/bg.jpg') center/cover no-repeat;
    opacity: 0.12;
    z-index: -2;
}
body::after {
    content: '';
    position: fixed;
    inset: 0;
    background: linear-gradient(180deg, rgba(8, 14, 26, 0.88) 0%, rgba(7, 12, 22, 0.94) 55%, rgba(5, 8, 16, 0.98) 100%);
    z-index: -1;
}

a { color: var(--color-accent); text-decoration: none; transition: color var(--transition-fast), opacity var(--transition-fast); }
a:hover, a:focus { color: var(--color-accent-strong); }

img { max-width: 100%; height: auto; display: block; }
button { font-family: inherit; }

.app-shell { min-height: 100vh; display: flex; flex-direction: column; }

/* Header */
.app-header {
    display: flex; align-items: center; justify-content: space-between;
    padding: 1rem 1.5rem;
    background: rgba(8, 14, 26, 0.82);
    backdrop-filter: blur(18px);
    border-bottom: 1px solid rgba(94, 234, 212, 0.18);
    box-shadow: 0 18px 32px rgba(2, 6, 23, 0.4);
    position: sticky; top: 0; z-index: 20;
}
.header-primary { display: flex; align-items: center; gap: 1rem; }

.brand {
    display: inline-flex; align-items: center; gap: 0.75rem;
    padding: 0.35rem 0.75rem; border-radius: var(--radius-md);
    background: rgba(18, 28, 48, 0.7);
    border: 1px solid rgba(94, 234, 212, 0.18);
    transition: transform var(--transition-fast), background var(--transition-fast);
}
.brand:hover, .brand:focus { transform: translateY(-1px); background: rgba(30, 41, 59, 0.85); }
.brand-text { font-size: 1rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--color-text-muted); }

.header-actions { display: flex; gap: 0.75rem; align-items: center; }
.header-link {
    display: inline-flex; align-items: center; justify-content: center;
    padding: 0.5rem 0.95rem; border-radius: var(--radius-sm); font-weight: 600;
    color: var(--color-text); background: rgba(18, 28, 48, 0.7);
    border: 1px solid rgba(94, 234, 212, 0.16);
}
.header-link:hover, .header-link:focus { background: rgba(30, 41, 59, 0.85); border-color: rgba(148, 163, 184, 0.4); }

/* Burger mobile */
.nav-toggle {
    display: none; flex-direction: column; gap: 0.3rem;
    background: rgba(18, 28, 48, 0.7); border: 1px solid rgba(94, 234, 212, 0.2);
    border-radius: var(--radius-sm); padding: 0.5rem; cursor: pointer;
    transition: background var(--transition-fast), border-color var(--transition-fast);
}
.nav-toggle:hover, .nav-toggle:focus { background: rgba(30, 41, 59, 0.9); border-color: rgba(148, 163, 184, 0.5); }
.nav-toggle-bar { width: 1.35rem; height: 2px; background: var(--color-text); border-radius: 999px; }

.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

/* Nav */
.app-nav { background: rgba(8, 14, 26, 0.78); border-bottom: 1px solid rgba(94, 234, 212, 0.16); }
.nav-list { list-style: none; margin: 0; padding: 0.5rem 1.5rem; display: flex; flex-wrap: wrap; align-items: center; gap: 0.5rem; }
.nav-item { position: relative; }

.nav-link {
    display: inline-flex; align-items: center; justify-content: center;
    padding: 0.6rem 1.15rem; border-radius: var(--radius-sm); font-weight: 600;
    color: var(--color-text); background: rgba(18, 28, 48, 0.6);
    border: 1px solid rgba(94, 234, 212, 0.16); min-width: 90px;
    transition: background var(--transition-fast), transform var(--transition-fast), border-color var(--transition-fast);
}
.nav-link:hover, .nav-link:focus { background: rgba(30, 41, 59, 0.85); border-color: rgba(148, 163, 184, 0.4); transform: translateY(-1px); }

.nav-item.is-active > .nav-link {
    background: linear-gradient(135deg, rgba(94, 234, 212, 0.9), rgba(34, 211, 238, 0.78));
    border-color: rgba(94, 234, 212, 0.7);
    box-shadow: 0 12px 28px rgba(94, 234, 212, 0.28);
}
.nav-item.cta > .nav-link {
    background: linear-gradient(135deg, rgba(34, 197, 94, 0.9), rgba(16, 185, 129, 0.85));
    border-color: rgba(34, 197, 94, 0.7); color: #032029;
}
.nav-item.cta > .nav-link:hover, .nav-item.cta > .nav-link:focus {
    background: linear-gradient(135deg, rgba(74, 222, 128, 0.95), rgba(20, 184, 166, 0.9));
}

/* -------- Sous-menus : hover stable, pas de trou, z-index élevé -------- */
.nav-item.has-submenu { position: relative; }

/* Panneau du sous-menu */
.nav-item.has-submenu > .submenu {
    list-style: none;
    position: absolute;
    left: 0;
    top: 100%;
    margin-top: 0.25rem;            /* colle au bouton → pas de trou */
    background: rgba(8, 14, 26, 0.95);
    border: 1px solid rgba(94, 234, 212, 0.18);
    border-radius: var(--radius-md);
    padding: 0.5rem;
    min-width: 14rem;
    box-shadow: var(--shadow-md);
    z-index: 99999;                 /* toujours au-dessus */
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateY(0.4rem);
    transition: opacity var(--transition-fast), transform var(--transition-fast), visibility var(--transition-fast);
}

/* Pont invisible entre l’onglet et la box pour éviter la fermeture quand on descend */
.nav-item.has-submenu::after {
    content: "";
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    height: 12px;                   /* zone tampon */
}

/* Ouverture au survol ET au focus clavier */
.nav-item.has-submenu:hover > .submenu,
.nav-item.has-submenu:focus-within > .submenu {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateY(0);
}

.submenu li { margin: 0; }
.submenu-link { display: block; padding: 0.55rem 0.75rem; border-radius: var(--radius-sm); color: var(--color-text); }
.submenu-link:hover, .submenu-link:focus { background: rgba(56, 189, 248, 0.15); color: var(--color-accent); }

/* Toggle (affiché en mobile) */
.submenu-toggle {
    display: none;
    position: absolute;
    right: 0.35rem; top: 0.35rem;
    background: transparent; border: none; color: inherit; cursor: pointer; padding: 0.35rem;
}
.submenu-toggle-icon {
    display: inline-block; width: 0.65rem; height: 0.65rem;
    border-right: 2px solid currentColor; border-bottom: 2px solid currentColor;
    transform: rotate(45deg);
    transition: transform var(--transition-fast);
}
.nav-item.has-submenu.is-expanded > .submenu-toggle .submenu-toggle-icon { transform: rotate(-135deg); }

/* Contenu principal */
.app-main { flex: 1; padding: 2.5rem 1.5rem 3rem; }
.app-content { width: min(var(--max-width), 100%); margin: 0 auto; }

.app-feedback {
    background: rgba(248, 113, 113, 0.12);
    border: 1px solid rgba(248, 113, 113, 0.35);
    border-radius: var(--radius-md);
    padding: 1rem 1.5rem;
    color: var(--color-danger);
    font-weight: 600;
    text-align: center;
}

/* Footer */
.app-footer {
    padding: 1.5rem; text-align: center; color: var(--color-text-muted);
    font-size: 0.95rem; background: rgba(15, 23, 42, 0.8);
    border-top: 1px solid rgba(148, 163, 184, 0.2);
}
.app-footer a { color: inherit; text-decoration: underline; }

/* Mobile / Tablette */
@media (max-width: 960px) {
    .app-header { position: static; flex-wrap: wrap; gap: 1rem; }
    .header-actions { width: 100%; justify-content: flex-end; order: 3; }

    .nav-toggle { display: inline-flex; }
    .app-nav { max-height: 0; overflow: hidden; transition: max-height 220ms ease-in-out; }
    .app-nav.is-open { max-height: 620px; }

    .nav-list { flex-direction: column; align-items: stretch; gap: 0.35rem; padding: 0.75rem 1rem 1.25rem; }
    .nav-link { justify-content: space-between; width: 100%; }

    /* Sous-menus en mode “accordéon” sur mobile */
    .nav-item.has-submenu > .submenu {
        position: static;
        display: none;
        margin-top: 0.35rem;
        padding: 0.35rem;
        background: rgba(30, 41, 59, 0.85);
        opacity: 1; visibility: visible; pointer-events: auto; transform: none;
        z-index: auto;
    }
    .nav-item.has-submenu.is-expanded > .submenu { display: block; }
    .submenu-toggle { display: inline-flex; align-items: center; justify-content: center; color: var(--color-text-muted); }
}

/* Optionnel : un peu plus large sur très grands écrans */
@media (min-width: 1800px) {
    :root { --max-width: clamp(320px, 92vw, 1720px); }
}