:root {
    --primary: #87ceeb;
    --accent: #7ed957;
    --bg: #f8fcff;
    --text: #222;
    --white: #ffffff;
}

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

body {
    font-family:
        "Zen Maru Gothic",
        "Yu Gothic",
        sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
}

header {
    background: var(--primary);
    color: white;
    padding: 1rem 2rem;
    position: sticky;
    top: 0;
}

.header-inner {
    max-width: 1200px;
    margin: auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.8rem;
    font-weight: bold;
}

nav ul {
    display: flex;
    list-style: none;
    gap: 1rem;
}

nav a {
    text-decoration: none;
    color: white;
    font-weight: bold;
}

.hero {
    max-width: 1000px;
    margin: 60px auto;
    text-align: center;
    padding: 0 20px;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 20px;
}

.hero p {
    margin-bottom: 40px;
}

.button-grid {
    display: grid;
    gap: 20px;
    grid-template-columns: repeat(auto-fit,minmax(250px,1fr));
}

.card-button {
    background: white;
    border-radius: 15px;
    padding: 30px;
    text-decoration: none;
    color: var(--text);
    box-shadow: 0 2px 10px rgba(0,0,0,.1);
    transition: .3s;
}

.card-button:hover {
    transform: translateY(-5px);
}

.card-button h2 {
    color: var(--accent);
    margin-bottom: 10px;
}

.section {
    max-width: 1000px;
    margin: 40px auto;
    padding: 0 20px;
}

.section h1 {
    margin-bottom: 20px;
    color: var(--accent);
}

.wordset-grid {
    display: grid;
    gap: 15px;
    grid-template-columns: repeat(auto-fill,minmax(180px,1fr));
}

.wordset-card {
    background: white;
    padding: 20px;
    border-radius: 12px;
    text-align: center;
    text-decoration: none;
    color: var(--text);
    box-shadow: 0 2px 10px rgba(0,0,0,.08);
}

.quiz-container {

    max-width: 800px;

    margin: 50px auto;

    padding: 20px;
}

#progress {

    margin-bottom: 20px;

    font-weight: bold;
}

#word {

    font-size: 2.5rem;

    margin-bottom: 10px;

    color: #333;
}

#partOfSpeech {

    margin-bottom: 30px;

    color: #666;
}

.question-text {

    font-size: 1.2rem;

    margin-bottom: 20px;
}

#choices {

    display: grid;

    gap: 15px;
}

.choice-btn {

    border: none;

    background: white;

    padding: 18px;

    border-radius: 10px;

    cursor: pointer;

    box-shadow: 0 2px 8px rgba(0,0,0,.1);

    font-size: 1rem;
}

.choice-btn:hover {

    background: #eef9ff;
}

.correct {

    background: #7ed957 !important;

    color: white;
}

.wrong {

    background: #ff6b6b !important;

    color: white;
}

#result {

    margin-top: 25px;

    font-size: 1.2rem;

    font-weight: bold;
}

#nextBtn {

    margin-top: 20px;

    padding: 12px 30px;

    border: none;

    border-radius: 10px;

    background: #87ceeb;

    color: white;

    cursor: pointer;
}

footer {
    margin-top: 80px;
    text-align: center;
    padding: 30px;
    background: #eaf7fc;
}

/* スマホメニュー */

.menu-btn {
    display: none;
    font-size: 2rem;
    cursor: pointer;
}

@media(max-width:768px){

    nav {
        display:none;
    }

    .menu-btn {
        display:block;
    }

    .mobile-menu {
        position: fixed;
        top:0;
        right:-260px;
        width:260px;
        height:100%;
        background:white;
        transition:.3s;
        padding-top:80px;
        box-shadow:-2px 0 10px rgba(0,0,0,.2);
    }

    .mobile-menu.open {
        right:0;
    }

    .mobile-menu ul {
        list-style:none;
    }

    .mobile-menu li {
        border-bottom:1px solid #ddd;
    }

    .mobile-menu a {
        display:block;
        padding:15px;
        text-decoration:none;
        color:#333;
    }

    .hero h1 {
        font-size:2rem;
    }
}