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

html {
    scroll-behavior: smooth;
}

body {
    font-family: Arial, Helvetica, sans-serif;
    background: #f4f7fb;
    color: #1f2937;
    line-height: 1.6;
}


/* =========================
   HEADER
========================= */

header {
    background: #0f172a;
    color: white;
    padding: 16px 5%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 15px;
    flex-wrap: wrap;
}

.logo {
    font-size: 21px;
    font-weight: bold;
}

nav {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

nav a {
    color: white;
    text-decoration: none;
    padding: 8px 12px;
    border-radius: 7px;
    font-size: 14px;
}

nav a:hover,
nav a.active {
    background: #2563eb;
}


/* =========================
   MAIN
========================= */

main {
    width: 92%;
    max-width: 1100px;
    margin: 25px auto;
}

section {
    background: white;
    margin-bottom: 22px;
    padding: 25px;
    border-radius: 14px;
    box-shadow: 0 3px 15px rgba(0, 0, 0, 0.07);
}

h1,
h2,
h3 {
    margin-bottom: 12px;
}

h1 {
    font-size: 30px;
}

h2 {
    font-size: 24px;
    color: #0f172a;
}

h3 {
    color: #1d4ed8;
}

p {
    margin-bottom: 10px;
}


/* =========================
   HERO
========================= */

.hero {
    text-align: center;
    background: #eaf2ff;
    border: 1px solid #c7dcff;
}

.hero h1 {
    color: #0f172a;
}

.hero p {
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}


/* =========================
   CARDS
========================= */

.cards {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 18px;
}

.card {
    background: white;
    border: 1px solid #e2e8f0;
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 16px;
}

.cards .card {
    margin-bottom: 0;
}


/* =========================
   LESSON CARDS
========================= */

.lesson-card {
    background: white;
    border: 1px solid #e2e8f0;
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 16px;
}


/* =========================
   LISTES
========================= */

ul,
ol {
    margin-left: 25px;
    margin-bottom: 15px;
}

li {
    margin-bottom: 6px;
}


/* =========================
   FORMULES
========================= */

.math,
.formule {
    background: #f8fafc;
    border-left: 4px solid #2563eb;
    padding: 14px;
    margin: 15px 0;
    border-radius: 7px;
    font-size: 18px;
    font-weight: bold;
    overflow-x: auto;
}


/* =========================
   BOUTONS
========================= */

.button,
button,
input[type="submit"] {
    display: inline-block;
    background: #2563eb;
    color: white;
    border: none;
    text-decoration: none;
    padding: 11px 17px;
    border-radius: 8px;
    cursor: pointer;
    font-weight: bold;
    font-size: 15px;
}

.button:hover,
button:hover,
input[type="submit"]:hover {
    background: #1d4ed8;
}


/* =========================
   FORMULAIRES
========================= */

form {
    width: 100%;
}

label {
    display: block;
    margin-bottom: 6px;
    font-weight: bold;
}

input,
textarea,
select {
    width: 100%;
    padding: 11px;
    margin-bottom: 12px;
    border: 1px solid #cbd5e1;
    border-radius: 7px;
    background: white;
    color: #1f2937;
    font-size: 15px;
}

textarea {
    min-height: 120px;
    resize: vertical;
}

input:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: #2563eb;
}


/* =========================
   EXERCICES
========================= */

.exercise {
    background: #f8fafc;
    border: 1px solid #e2e8f0;
    border-radius: 10px;
    padding: 18px;
    margin-bottom: 18px;
}


/* =========================
   CORRIGES
========================= */

details {
    background: #eff6ff;
    border: 1px solid #bfdbfe;
    border-radius: 9px;
    padding: 13px;
    margin-top: 12px;
}

summary {
    cursor: pointer;
    color: #1d4ed8;
    font-weight: bold;
}


/* =========================
   SCORE
========================= */

.score {
    background: #ecfdf5;
    border: 1px solid #a7f3d0;
    border-radius: 12px;
    padding: 22px;
    text-align: center;
}


/* =========================
   RESULTATS
========================= */

.correct {
    background: #ecfdf5;
    border-left: 4px solid #10b981;
    padding: 13px;
    border-radius: 7px;
}

.incorrect {
    background: #fef2f2;
    border-left: 4px solid #ef4444;
    padding: 13px;
    border-radius: 7px;
}


/* =========================
   TABLEAUX
========================= */

.table-container {
    width: 100%;
    overflow-x: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 15px;
}

th,
td {
    padding: 11px;
    border: 1px solid #dbe3ec;
    text-align: center;
}

th {
    background: #0f172a;
    color: white;
}

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


/* =========================
   GRAPHISME SVG
========================= */

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


/* =========================
   DASHBOARD
========================= */

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


/* =========================
   FOOTER
========================= */

footer {
    background: #0f172a;
    color: white;
    text-align: center;
    padding: 25px 15px;
    margin-top: 35px;
}

footer p {
    margin-bottom: 5px;
}


/* =========================
   TABLET
========================= */

@media (max-width: 800px) {

    header {
        flex-direction: column;
        text-align: center;
    }

    nav {
        justify-content: center;
    }

    .cards {
        grid-template-columns: 1fr;
    }

    .dashboard {
        grid-template-columns: 1fr;
    }

}


/* =========================
   TELEPHONE
========================= */

@media (max-width: 600px) {

    body {
        font-size: 14px;
    }

    header {
        padding: 14px 3%;
    }

    .logo {
        font-size: 18px;
    }

    nav {
        width: 100%;
        justify-content: center;
    }

    nav a {
        font-size: 12px;
        padding: 7px 8px;
    }

    main {
        width: 94%;
        margin: 18px auto;
    }

    section {
        padding: 18px;
        border-radius: 10px;
    }

    h1 {
        font-size: 25px;
    }

    h2 {
        font-size: 21px;
    }

    h3 {
        font-size: 18px;
    }

    .hero {
        padding: 28px 16px;
    }

    .card {
        padding: 16px;
    }

    .math,
    .formule {
        font-size: 16px;
    }

    .button,
    button,
    input[type="submit"] {
        width: 100%;
        text-align: center;
    }

    th,
    td {
        padding: 8px 5px;
        font-size: 12px;
    }

}


/* =========================
   PETIT TELEPHONE
========================= */

@media (max-width: 380px) {

    nav a {
        font-size: 11px;
        padding: 6px;
    }

    h1 {
        font-size: 22px;
    }

    h2 {
        font-size: 19px;
    }

}