/* Trang chủ — calm study presentation layer. */
body { background: var(--color-background); color: var(--color-text); }
.navbar { background: rgb(241 245 246 / .95); border-bottom-color: var(--color-border); box-shadow: var(--shadow-xs); }
.navbar .logo, .navbar .nav-links a, .navbar .menu-toggle { color: var(--color-text); }
.navbar .logo .dot, .navbar .nav-links a:hover, .navbar .nav-links a.active { color: var(--color-primary); }
.hero-section { background: radial-gradient(circle at 82% 24%, rgb(134 171 196 / .24), transparent 24rem), linear-gradient(160deg, var(--color-background-subtle), var(--color-background)); }
.hero-title, .section-header h2, .course-card h3 { color: var(--color-text); }
.hero-subtitle, .section-header p, .course-card p, .stat-label { color: var(--color-text-secondary); }
.gradient-text { background: var(--gradient-main); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.floating-card, .course-card { background: var(--color-surface-raised); border-color: var(--color-border); box-shadow: var(--shadow-sm); }
.floating-card .korean-char, .stat-number { color: var(--color-primary); }
.course-card:hover { border-color: var(--blue-300); box-shadow: var(--shadow-lg); }
.card-icon { background: var(--color-primary-subtle); color: var(--color-primary); }
.progress-bar-bg { background: var(--slate-100); }
.progress-bar-fill { background: var(--color-success); }
.card-link { color: var(--color-primary); }
.btn-secondary { color: var(--color-primary); background: var(--color-surface-raised); border-color: var(--blue-200); }
.footer { background: var(--blue-800); border-top-color: rgb(255 255 255 / .1); }
.footer p, .footer a { color: #d9e6f1; }

/* Giới thiệu phương pháp học và thẻ minh họa tương tác. */
.method-section { max-width: 1200px; margin: 0 auto; padding: 88px 32px; }
.method-intro { max-width: 660px; margin-bottom: 40px; }
.method-intro h2 { margin: 14px 0 18px; font-size: clamp(2rem, 4vw, 3.2rem); line-height: 1.2; letter-spacing: -.035em; color: var(--color-text); }
.method-intro > p { color: var(--color-text-secondary); font-size: 1.1rem; line-height: 1.75; }
.method-layout { display: grid; grid-template-columns: 1fr 1fr; gap: 64px; align-items: start; }
.method-demo { padding: 28px; background: var(--color-surface-raised); border: 1px solid var(--color-border-strong); border-radius: 28px; box-shadow: var(--shadow-sm); }
.method-demo-label { display: flex; justify-content: space-between; gap: 12px; color: var(--color-text-secondary); font-size: .85rem; }
.method-demo-label span:last-child { color: var(--color-primary); }
.method-word { text-align: center; font-size: clamp(3rem, 7vw, 4.5rem); font-weight: 700; color: var(--color-primary); padding: 36px 0 12px; }
.method-prompt { text-align: center; color: var(--color-text-secondary); line-height: 1.6; margin-bottom: 28px; }
.method-answer { border-radius: 18px; background: #e1f1ed; color: #254c45; }
.method-answer summary { padding: 18px; cursor: pointer; font-weight: 600; list-style: none; display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.method-answer summary::-webkit-details-marker { display: none; }
.method-answer summary:focus-visible, .method-cta:focus-visible { outline: 3px solid var(--color-focus); outline-offset: 4px; }
.method-answer[open] summary i { transform: rotate(180deg); }
.method-answer-content { padding: 0 20px 22px; line-height: 1.65; }
.method-answer-content h3 { font-size: 1.6rem; margin-bottom: 8px; }
.method-example { margin-top: 16px; padding-top: 16px; border-top: 1px solid #b8d6ce; }
.method-example p + p { margin-top: 6px; }
.method-demo-note { display: flex; align-items: baseline; gap: 8px; font-size: .85rem; color: var(--color-text-secondary); margin-top: 22px; line-height: 1.6; }
.method-steps { list-style: none; padding: 0; margin: 0; display: grid; gap: 26px; }
.method-steps li { display: flex; align-items: flex-start; gap: 18px; }
.method-number { flex: 0 0 42px; height: 42px; display: grid; place-items: center; background: var(--color-primary-subtle); color: var(--color-primary); border-radius: 14px; font-weight: 600; font-size: .9rem; }
.method-steps h3 { font-size: 1.2rem; margin: 5px 0 8px; color: var(--color-text); }
.method-steps p { color: var(--color-text-secondary); line-height: 1.7; }
.method-bottom { margin-top: 40px; padding-top: 28px; border-top: 1px solid var(--color-border-strong); display: flex; align-items: center; justify-content: space-between; gap: 20px; }
.method-bottom p { color: var(--color-text-secondary); }
.method-cta { display: inline-flex; align-items: center; gap: 12px; padding: 15px 22px; border-radius: 999px; background: var(--color-primary); color: white; text-decoration: none; font-weight: 600; flex-shrink: 0; }
.method-cta:hover { background: var(--color-primary-hover); color: white; }
@media (max-width: 760px) {
    .method-section { padding: 56px 20px; }
    .method-layout { grid-template-columns: 1fr; gap: 32px; }
    .method-demo { padding: 22px; }
    .method-bottom { align-items: flex-start; flex-direction: column; }
}

.listening-method { margin-top: 48px; padding: clamp(24px, 4vw, 40px); border-radius: 24px; background: var(--color-surface); border: 1px solid var(--color-border-strong); }
.listening-method h3 { font-size: clamp(1.5rem, 3vw, 2rem); margin: 8px 0 18px; color: var(--color-text); }
.listening-method p { color: var(--color-text-secondary); line-height: 1.8; margin-top: 16px; }
.listening-moments { display: flex; flex-wrap: wrap; gap: 10px; margin: 22px 0; }
.listening-moments span { padding: 8px 14px; border-radius: 999px; color: var(--color-primary); background: var(--color-primary-subtle); font-size: .9rem; }
.listening-research { margin-top: 24px; padding-top: 20px; border-top: 1px solid var(--color-border); }
.listening-research summary { cursor: pointer; color: var(--color-primary); font-weight: 600; }
.listening-research a { color: var(--color-primary); text-decoration: underline; text-underline-offset: 3px; }
.listening-method .listening-note { font-size: .85rem; }
.listening-method > p a { color: var(--color-primary); text-decoration: underline; text-underline-offset: 3px; }