/* ============================
   RESET & BASE
============================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --blue-main: #0a84ff;
    --blue-soft: #3b82f6;

    --black-main: #0b0f14;
    --black-soft: #121826;

    --text-dark: #0b0f14;
    --text-light: #9ca3af;

    --bg-white: #ffffff;
    --bg-light: #f5f7fa;

    --border-color: rgba(255, 255, 255, 0.12);
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI",
                 Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-white);
}

/* ============================
   LAYOUT
============================ */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

/* ============================
   HEADER
============================ */
header {
    background: linear-gradient(
        135deg,
        var(--black-main),
        var(--black-soft),
        var(--blue-main)
    );
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow);
}

/* ============================
   LOGO
============================ */
.logo {
    color: #ffffff;
    font-size: 1.2rem;
    font-weight: 700;
    letter-spacing: 0.6px;
    white-space: nowrap;
}

/* ============================
   NAVIGATION
============================ */
nav ul {
    list-style: none;
    display: flex;
    align-items: center;
    gap: 22px;
}

nav a {
    color: rgba(255, 255, 255, 0.85);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    position: relative;
    transition: color 0.3s ease;
}

nav a:hover {
    color: #ffffff;
}

/* underline animation */
nav a::after {
    content: "";
    position: absolute;
    left: 0;
    bottom: -6px;
    width: 0;
    height: 2px;
    background: var(--blue-soft);
    transition: width 0.3s ease;
}

nav a:hover::after,
nav a.active::after {
    width: 100%;
}

/* ============================
   LANG SWITCH
============================ */
.lang-switch {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 7px 12px;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.12);
    font-size: 0.85rem;
    line-height: 1;
    border: 1px solid rgba(255, 255, 255, 0.18);
}

.lang-switch:hover {
    background: rgba(255, 255, 255, 0.22);
}

/* no underline animation for lang button */
nav a.lang-switch::after {
    display: none;
}

/* ============================
   HERO
============================ */
.hero {
    padding: 90px 0 70px;
    background: var(--bg-white);
}

.hero-content h2 {
    font-size: 2.6rem;
    font-weight: 800;
    margin-bottom: 12px;
    color: var(--text-dark);
}

.intro {
    margin-bottom: 28px;
}

.subtitle {
    color: #4b5563;
    font-size: 1.05rem;
    margin-top: 4px;
}

/* ============================
   HERO BUTTONS / SECTION CARDS
============================ */
.main-sections {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    margin-top: 10px;
}

.section-card {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 12px 18px;
    border-radius: 999px;

    text-decoration: none;
    font-weight: 600;
    font-size: 0.95rem;

    background: #fff;
    border: 2px solid currentColor;
    color: var(--text-dark);

    transition: transform 0.2s ease, box-shadow 0.25s ease;
}

.section-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.12);
}

.section-card .icon {
    font-size: 1.1rem;
}

/* Colors (match your classes in HTML) */
.section-card.formation { color: #ef4444; }   /* red */
.section-card.recherche { color: #2563eb; }   /* blue */
.section-card.innovation { color: #f97316; }  /* orange */
.section-card.about { color: #7c3aed; }       /* purple */

/* ============================
   PAGE HEADER
============================ */
.page-header {
    padding: 70px 0;
    background: linear-gradient(
        180deg,
        var(--black-main),
        var(--bg-white)
    );
    text-align: center;
}

.page-header h1 {
    font-size: 2.2rem;
    margin-bottom: 10px;
    color: #ffffff;
}

.page-subtitle {
    color: rgba(255, 255, 255, 0.75);
}

/* ============================
   SECTIONS
============================ */
.section {
    padding: 80px 0;
}

.section.alt {
    background-color: var(--bg-light);
}

/* ============================
   HIGHLIGHTS
============================ */
.highlights h2 {
    font-size: 2rem;
    margin-bottom: 26px;
}

.highlight-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 18px;
}

.highlight-card {
    background: #fff;
    border-radius: 16px;
    padding: 22px;
    box-shadow: var(--shadow);
}

.card-icon {
    display: inline-flex;
    font-size: 1.3rem;
    margin-bottom: 10px;
}

.highlight-card h3 {
    font-size: 1.2rem;
    margin-bottom: 8px;
}

.highlight-card p {
    color: #4b5563;
    margin-bottom: 12px;
}

.card-link {
    color: var(--blue-main);
    text-decoration: none;
    font-weight: 600;
}

.card-link:hover {
    text-decoration: underline;
}

/* ============================
   TIMELINE (Formation / Education)
============================ */
.timeline {
    display: grid;
    gap: 18px;
}

.timeline-item {
    background: #fff;
    padding: 22px;
    border-radius: 16px;
    box-shadow: var(--shadow);
}

.timeline-date {
    color: #6b7280;
    font-weight: 600;
    margin-bottom: 8px;
}

.institution {
    color: #6b7280;
    margin-bottom: 10px;
}

.courses h4 {
    margin-top: 12px;
    margin-bottom: 8px;
}

/* ============================
   SKILLS GRID
============================ */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 18px;
}

.skill-category {
    background: #fff;
    padding: 22px;
    border-radius: 16px;
    box-shadow: var(--shadow);
}

.skill-category h3 {
    margin-bottom: 10px;
}

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

.skill-list li {
    padding: 6px 0;
    color: #374151;
    border-bottom: 1px solid #eef2f7;
}

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

/* ============================
   ABOUT / SERVICES CARDS
============================ */
.about-section {
    margin-bottom: 60px;
}

.about-section h2 {
    margin-bottom: 16px;
    font-size: 1.5rem;
}

.about-content {
    background: #ffffff;
    padding: 24px;
    border-radius: 14px;
    box-shadow: var(--shadow);
}

.about-content ul {
    margin-top: 12px;
    padding-left: 18px;
}

.about-content li {
    margin-bottom: 6px;
}

/* ============================
   CONTACT
============================ */
.contact-content {
    display: grid;
    gap: 16px;
}

.contact-info {
    display: grid;
    gap: 10px;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 10px;
}

.social-links {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.social-link {
    display: inline-flex;
    padding: 10px 14px;
    border-radius: 999px;
    border: 1px solid #e5e7eb;
    text-decoration: none;
    color: var(--text-dark);
    background: #fff;
}

.social-link:hover {
    border-color: #cbd5e1;
}

/* ============================
   BUTTON (generic)
============================ */
.button {
    display: inline-block;
    margin-top: 20px;
    padding: 10px 18px;
    border-radius: 8px;
    background: var(--blue-main);
    color: #ffffff;
    text-decoration: none;
    font-weight: 500;
    transition: background 0.3s ease, transform 0.2s ease;
}

.button:hover {
    background: #006ee6;
    transform: translateY(-2px);
}

/* ============================
   FOOTER
============================ */
footer {
    background: var(--black-main);
    color: rgba(255, 255, 255, 0.7);
    padding: 30px 0;
    text-align: center;
}

.footer-links a {
    color: rgba(255, 255, 255, 0.85);
    text-decoration: none;
}

.footer-links a:hover {
    color: var(--blue-soft);
}

/* ============================
   RESPONSIVE
============================ */
@media (max-width: 980px) {
    .highlight-grid {
        grid-template-columns: 1fr;
    }
    .skills-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        height: auto;
        padding: 12px 0;
    }

    nav ul {
        flex-wrap: wrap;
        justify-content: center;
        gap: 14px;
        margin-top: 8px;
    }

    .main-sections {
        justify-content: center;
    }
}

@media (max-width: 540px) {
    .skills-grid {
        grid-template-columns: 1fr;
    }
}