:root {
    --bg-main: #f4f9f4; /* สีพื้นหลัง */
    --primary-purple: #c8b6e2; /* ม่วงพาสเทล */
    --secondary-green: #a8e6cf; /* เขียวพาสเทล */
    --text-dark: #333333;
    --white: #ffffff;
}

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

body {
    font-family: 'Prompt', sans-serif;
    background-color: var(--bg-main);
    color: var(--text-dark);
    line-height: 1.8;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

header {
    background: linear-gradient(135deg, var(--primary-purple), var(--secondary-green));
    padding: 2.5rem 1rem;
    text-align: center;
    border-bottom-left-radius: 0px;
    border-bottom-right-radius: 0px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}

header h1 { font-size: 2.2rem; color: #4a3f5a; text-shadow: 2px 2px 4px rgb(255, 255, 255); }

nav {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 5px;
    padding: 15px;
    background: var(--white);
    position: sticky;
    top: 0;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
    z-index: 100;
}

nav a {
    text-decoration: none;
    color: var(--text-dark);
    background-color: var(--bg-main);
    padding: 6px 10px;
    border-radius: 15px;
    font-weight: 600;
    transition: 0.3s;
    border: 2px solid var(--secondary-green);
}

nav a:hover, nav a.active {
    background-color: var(--secondary-green);
    color: #2b5c47;
}

.container {
    max-width: 900px;
    margin: 30px auto;
    padding: 20px;
    background-color: var(--white);
    border-radius: 15px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.03);
    border-top: 6px solid var(--primary-purple);
    flex-grow: 1;
}

h2 {
    color: #5c4b75;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px dashed var(--secondary-green);
}

p, li { font-size: 1.1rem; margin-bottom: 15px; }

ul { margin-left: 30px; margin-bottom: 20px; }

/* การจัดการรูปภาพประกอบ */
.content-img {
    max-width: 100%;
    height: auto;
    border-radius: 15px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.1);
    margin: 20px auto;
    display: block;
    border: 3px solid var(--secondary-green);
}

/* กล่องเน้นข้อความ */
.highlight-box {
    background-color: #f0f7f4;
    padding: 15px;
    border-left: 5px solid var(--secondary-green);
    border-radius: 5px;
    margin: 20px 0;
}

footer {
    text-align: center;
    padding: 20px;
    background-color: var(--primary-purple);
    color: var(--white);
    margin-top: auto;
}
/* =========================================
   สไตล์สำหรับหน้า Landing Page (index.html)
   ========================================= */
.landing-bg {
    background: linear-gradient(135deg, #e0c3fc 0%, #8ec5fc 100%); /* ไล่สีพาสเทล ม่วง-ฟ้าเขียว */
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
}

.hero-container {
    background-color: rgba(255, 255, 255, 0.95);
    max-width: 800px;
    width: 100%;
    border-radius: 30px;
    padding: 50px 30px;
    text-align: center;
    box-shadow: 0 20px 40px rgba(0,0,0,0.1);
    border: 4px solid var(--white);
}

.badge {
    display: inline-block;
    background-color: var(--secondary-green);
    color: #2b5c47;
    padding: 8px 20px;
    border-radius: 20px;
    font-weight: 600;
    font-size: 1rem;
    margin-bottom: 20px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}

.hero-content h1 {
    font-size: 2.8rem;
    color: #4a3f5a;
    line-height: 1.3;
    margin-bottom: 15px;
}

.hero-content h1 span {
    color: #7b5ea7;
    font-size: 2.2rem;
}

.hero-content p {
    font-size: 1.2rem;
    color: #666;
    margin-bottom: 30px;
}

.hero-image {
    max-width: 100%;
    height: auto;
    border-radius: 20px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.08);
    margin-bottom: 40px;
    border: 5px solid var(--bg-main);
}

/* ปุ่มเข้าสู่บทเรียน (ออกแบบให้มีมิติน่ากด) */
.btn-start {
    display: inline-block;
    background: linear-gradient(to bottom, #b598d9, #9b7bc2);
    color: white;
    font-size: 1.5rem;
    font-weight: 700;
    text-decoration: none;
    padding: 15px 40px;
    border-radius: 50px;
    box-shadow: 0 8px 0 #7a5a9e, 0 15px 20px rgba(0,0,0,0.2);
    transition: all 0.2s ease;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.2);
}

.btn-start:hover {
    transform: translateY(3px);
    box-shadow: 0 5px 0 #7a5a9e, 0 10px 15px rgba(0,0,0,0.2);
    color: white;
}

.btn-start:active {
    transform: translateY(8px);
    box-shadow: 0 0 0 #7a5a9e, 0 5px 5px rgba(0,0,0,0.2);
}