/* ==========================================
   Python3エンジニア試験ラボ プロダクトサイト
   アクセント: Pythonブランドカラー（ブルー #3776ab × イエロー #ffd43b）
   ========================================== */

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

:root {
  --navy: #12395e;
  --blue: #3776ab;
  --blue-dark: #2b5f8a;
  --blue-light: #e8f1f8;
  --yellow: #ffd43b;
  --yellow-light: #fff6d6;
  --yellow-deep: #b8860b;
  --gray-50: #f7f9fc;
  --gray-100: #edf2f7;
  --gray-300: #c8d8e8;
  --gray-400: #8fa5be;
  --gray-500: #6c86a0;
  --gray-600: #4a6882;
  --gray-700: #3a5570;
  --gray-900: #1a2e3f;
  --white: #ffffff;
  --radius: 16px;
  --shadow: 0 2px 16px rgba(18,57,94,.08);
  --shadow-lg: 0 8px 40px rgba(18,57,94,.14);
}

html { scroll-behavior: smooth; overflow-x: hidden; }
/* 追従ヘッダー（76px）にページ内リンクの着地点が隠れないようにする */
[id] { scroll-margin-top: 90px; }
body { font-family: 'Noto Sans JP', 'Inter', sans-serif; font-size: 17px; line-height: 1.75; color: var(--gray-900); background: var(--white); -webkit-font-smoothing: antialiased; overflow-x: hidden; }
img { max-width: 100%; height: auto; display: block; }
a { color: inherit; text-decoration: none; }

.container { max-width: 1100px; margin: 0 auto; padding: 0 24px; }
.eyebrow { font-size: 12px; font-weight: 700; letter-spacing: .12em; color: var(--blue); text-transform: uppercase; display: block; margin-bottom: 10px; }
.accent-blue { color: var(--blue); }
.marker-yellow { background: linear-gradient(transparent 62%, var(--yellow) 62%, var(--yellow) 92%, transparent 92%); }

h1 { font-size: clamp(2rem, 5vw, 3rem); font-weight: 900; line-height: 1.25; color: var(--navy); }
h2 { font-size: clamp(1.45rem, 3vw, 2rem); font-weight: 800; line-height: 1.3; color: var(--navy); }
h3 { font-size: 1.05rem; font-weight: 700; line-height: 1.4; color: var(--navy); margin-bottom: 8px; }
.lead { font-size: 1.1rem; line-height: 1.85; color: var(--gray-600); }

/* ── Buttons ── */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; padding: 13px 26px; border-radius: 8px; font-weight: 700; font-size: .92rem; transition: all .18s; cursor: pointer; border: none; text-decoration: none; }
.btn-primary { background: var(--blue); color: var(--white); }
.btn-primary:hover { background: var(--blue-dark); transform: translateY(-1px); }
.btn-outline { background: var(--white); color: var(--navy); border: 2px solid var(--navy); }
.btn-outline:hover { background: var(--blue-light); }
.btn-buy { background: var(--navy); color: var(--white); width: 100%; font-size: 1rem; padding: 14px 20px; }
.btn-buy:hover { background: var(--blue-dark); transform: translateY(-1px); }
.btn-buy-featured { background: var(--blue); }
.btn-buy-featured:hover { background: var(--blue-dark); }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 32px; }

/* ── Header ── */
.kk-header { position: sticky; top: 0; z-index: 100; background: var(--white); border-bottom: 1px solid var(--gray-100); box-shadow: 0 1px 8px rgba(0,0,0,.05); }
.kk-header-inner { display: flex; align-items: center; justify-content: space-between; height: 76px; gap: 16px; }
.kk-brand { display: flex; align-items: center; gap: 10px; font-weight: 900; font-size: 1.15rem; color: var(--navy); flex-shrink: 0; }
.kk-brand-mark { width: 40px; height: 40px; border-radius: 10px; background: linear-gradient(135deg, var(--blue) 0 50%, var(--yellow) 50% 100%); display: inline-grid; place-items: center; color: var(--white); font-weight: 900; font-size: 1.05rem; font-family: 'Inter', sans-serif; flex-shrink: 0; }
.kk-brand-text { display: flex; flex-direction: column; line-height: 1.2; }
.kk-brand-sub { display: block; font-size: .66rem; font-weight: 700; color: var(--blue); letter-spacing: .08em; margin-top: 3px; }
.kk-nav { display: flex; align-items: center; gap: 4px; font-size: .9rem; font-weight: 700; }
.kk-nav a { padding: 8px 11px; border-radius: 999px; color: var(--gray-600); transition: color .15s; }
.kk-nav a:hover { color: var(--navy); }
.kk-nav-cta { background: var(--blue); color: var(--white) !important; padding: 8px 18px; border-radius: 6px; }
.kk-nav-cta:hover { background: var(--blue-dark) !important; }
.kk-nav-toggle { display: none; flex-direction: column; gap: 5px; cursor: pointer; padding: 8px; background: none; border: none; }
.kk-nav-toggle span { display: block; width: 22px; height: 2px; background: var(--navy); border-radius: 2px; transition: .2s; }
.kk-nav-toggle.is-open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.kk-nav-toggle.is-open span:nth-child(2) { opacity: 0; }
.kk-nav-toggle.is-open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ── Hero ── */
.kk-hero { background: linear-gradient(135deg, #e8f1f8 0%, #fdf8e3 100%); padding: 72px 0 56px; }
.kk-hero-inner { max-width: 800px; }
.hero-badge { display: inline-flex; align-items: center; gap: 8px; background: var(--white); border: 1px solid var(--gray-100); border-radius: 999px; padding: 6px 16px; font-size: .8rem; font-weight: 800; color: var(--blue-dark); box-shadow: var(--shadow); margin-bottom: 20px; }
.hero-badge .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--yellow); }

/* ── Stats bar ── */
.stats-bar { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; margin-top: 44px; }
.stat-item { background: var(--white); border: 1px solid var(--gray-100); border-radius: 12px; padding: 18px 16px; text-align: center; box-shadow: var(--shadow); }
.stat-value { font-size: 1.5rem; font-weight: 900; color: var(--navy); font-family: 'Inter', 'Noto Sans JP', sans-serif; line-height: 1.2; }
.stat-value small { font-size: .8rem; font-weight: 700; }
.stat-label { font-size: .76rem; font-weight: 700; color: var(--gray-500); margin-top: 4px; line-height: 1.5; }

/* ── Sections ── */
.section { padding: 80px 0; }
.section-sm { padding: 40px 0; }
.section-alt { background: var(--gray-50); }
.section-head { margin-bottom: 48px; }
.section-head.center { text-align: center; }
.section-head h2 { margin-top: 6px; margin-bottom: 14px; }
.section-head > p { color: var(--gray-600); }
.section-head.center > p { max-width: 640px; margin: 0 auto; }

/* ── Grid ── */
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 32px; align-items: start; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }

/* ── Card base ── */
.card { background: var(--white); border: 1px solid var(--gray-100); border-radius: var(--radius); padding: 28px; box-shadow: var(--shadow); }
.card h3 { margin: 0 0 10px; }

/* ── Pain list ── */
.pain-list { list-style: none; display: flex; flex-direction: column; gap: 14px; max-width: 820px; margin: 0 auto; }
.pain-list li { display: flex; align-items: flex-start; gap: 16px; background: var(--white); border: 1px solid var(--gray-100); border-radius: 12px; padding: 20px 24px; box-shadow: 0 1px 8px rgba(0,0,0,.04); }
.pain-icon { flex-shrink: 0; width: 26px; height: 26px; border-radius: 50%; background: rgba(200,40,40,.1); color: #c03030; display: flex; align-items: center; justify-content: center; font-size: 13px; font-weight: 900; margin-top: 2px; }
.pain-list li strong { display: block; font-size: 1rem; color: var(--navy); margin-bottom: 4px; }
.pain-list li p { font-size: .9rem; color: var(--gray-600); margin: 0; }

/* ── Reason cards ── */
.reason-card { position: relative; padding-top: 34px; }
.reason-number { position: absolute; top: -16px; left: 24px; width: 44px; height: 44px; border-radius: 12px; background: var(--yellow); color: var(--navy); display: grid; place-items: center; font-size: 1.1rem; font-weight: 900; font-family: 'Inter', sans-serif; box-shadow: var(--shadow); }
.reason-card h3 { font-size: 1.08rem; }
.reason-card p { font-size: .92rem; color: var(--gray-600); }
.reason-note { margin-top: 14px; padding: 10px 14px; background: var(--yellow-light); border-left: 3px solid var(--yellow); border-radius: 0 8px 8px 0; font-size: .82rem; color: var(--gray-700); line-height: 1.7; }

/* ── Price cards ── */
.price-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; align-items: stretch; }
.price-card { background: var(--white); border: 1px solid var(--gray-100); border-radius: var(--radius); padding: 28px 26px; box-shadow: var(--shadow); display: flex; flex-direction: column; position: relative; }
.price-card-featured { border: 2px solid var(--blue); box-shadow: var(--shadow-lg); }
.price-badge { position: absolute; top: -14px; left: 50%; transform: translateX(-50%); background: var(--yellow); color: var(--navy); font-size: .76rem; font-weight: 900; padding: 4px 18px; border-radius: 999px; white-space: nowrap; box-shadow: var(--shadow); }
.price-card-cat { font-size: .72rem; font-weight: 800; letter-spacing: .1em; color: var(--blue); text-transform: uppercase; margin-bottom: 6px; }
.price-card-title { font-size: 1.15rem; font-weight: 800; color: var(--navy); margin-bottom: 4px; line-height: 1.4; }
.price-card-target { font-size: .82rem; color: var(--gray-500); margin-bottom: 16px; }
.price-value { font-size: 2rem; font-weight: 900; color: var(--navy); font-family: 'Inter', 'Noto Sans JP', sans-serif; letter-spacing: -.02em; line-height: 1.1; margin-bottom: 2px; }
.price-value small { font-size: .82rem; font-weight: 700; color: var(--gray-500); letter-spacing: 0; }
.price-compare { font-size: .8rem; color: var(--gray-500); margin-bottom: 16px; }
.price-compare del { color: var(--gray-400); }
.price-compare strong { color: #c03030; font-weight: 800; }
.price-features { list-style: none; display: flex; flex-direction: column; gap: 8px; margin-bottom: 22px; flex: 1; }
.price-features li { position: relative; padding-left: 22px; font-size: .88rem; color: var(--gray-600); line-height: 1.6; }
.price-features li::before { content: '✓'; position: absolute; left: 0; top: 0; color: var(--blue); font-weight: 900; }
.price-note { font-size: .78rem; color: var(--gray-500); margin-top: 10px; text-align: center; line-height: 1.6; }

/* ── Compare table ── */
.compare-scroll { overflow-x: auto; -webkit-overflow-scrolling: touch; padding-bottom: 8px; }
.compare-table { width: 100%; min-width: 680px; border-collapse: separate; border-spacing: 0; background: var(--white); border: 1px solid var(--gray-100); border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow); font-size: .9rem; }
.compare-table th, .compare-table td { padding: 14px 16px; border-bottom: 1px solid var(--gray-100); text-align: center; vertical-align: middle; line-height: 1.6; }
.compare-table thead th { background: var(--gray-50); font-size: .85rem; color: var(--gray-600); font-weight: 800; }
.compare-table thead th.col-labo { background: var(--blue); color: var(--white); font-size: .92rem; }
.compare-table tbody th { text-align: left; font-weight: 700; color: var(--navy); background: var(--gray-50); font-size: .85rem; white-space: nowrap; }
.compare-table td.col-labo { background: var(--blue-light); font-weight: 700; color: var(--navy); }
.compare-table tr:last-child th, .compare-table tr:last-child td { border-bottom: none; }
.compare-yes { color: var(--blue); font-weight: 900; }
.compare-no { color: #c03030; font-weight: 700; }
.compare-caption { font-size: .78rem; color: var(--gray-500); margin-top: 12px; line-height: 1.7; }

/* ── Exam spec table ── */
.spec-table { width: 100%; border-collapse: collapse; background: var(--white); border: 1px solid var(--gray-100); border-radius: 12px; overflow: hidden; box-shadow: var(--shadow); font-size: .92rem; }
.spec-table th, .spec-table td { padding: 13px 18px; border-bottom: 1px solid var(--gray-100); text-align: left; line-height: 1.6; }
.spec-table th { background: var(--gray-50); color: var(--navy); font-weight: 700; width: 32%; white-space: nowrap; }
.spec-table tr:last-child th, .spec-table tr:last-child td { border-bottom: none; }

/* ── Flow ── */
.flow-steps { display: flex; flex-direction: column; max-width: 720px; margin: 0 auto; }
.flow-step { display: flex; gap: 16px; position: relative; padding-bottom: 28px; }
.flow-step:last-child { padding-bottom: 0; }
.flow-step::before { content: ''; position: absolute; left: 15px; top: 32px; bottom: 0; width: 2px; background: var(--gray-100); }
.flow-step:last-child::before { display: none; }
.flow-step-num { flex-shrink: 0; width: 32px; height: 32px; border-radius: 50%; background: var(--blue); color: var(--white); font-size: .78rem; font-weight: 900; display: flex; align-items: center; justify-content: center; position: relative; z-index: 1; }
.flow-step-body { padding-top: 4px; }
.flow-step-body h4 { font-size: 1rem; font-weight: 700; color: var(--navy); margin-bottom: 4px; }
.flow-step-body p { font-size: .9rem; color: var(--gray-600); }

/* ── Instructor ── */
.instructor { display: grid; grid-template-columns: 240px 1fr; gap: 40px; align-items: start; }
.instructor-photo img { border-radius: var(--radius); box-shadow: var(--shadow-lg); }
.instructor-name { font-size: 1.4rem; font-weight: 900; color: var(--navy); margin-bottom: 4px; }
.instructor-title { font-size: .88rem; color: var(--blue); font-weight: 700; margin-bottom: 16px; }
.instructor p { font-size: .95rem; color: var(--gray-600); }
.profile-links { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 20px; }
.profile-link { display: inline-flex; align-items: center; gap: 7px; padding: 9px 16px; border-radius: 999px; border: 1px solid var(--gray-100); background: var(--white); color: var(--navy); font-weight: 700; font-size: .88rem; transition: box-shadow .16s ease, color .16s ease; }
.profile-link:hover { box-shadow: var(--shadow); color: var(--blue); }

/* ── FAQ ── */
.faq-list { max-width: 760px; margin: 0 auto; display: flex; flex-direction: column; gap: 16px; }
.faq-q { font-size: .82rem; font-weight: 700; color: var(--blue); letter-spacing: .06em; margin-bottom: 6px; }
.faq-title { font-weight: 700; color: var(--navy); margin-bottom: 8px; }
.faq-a { font-size: .95rem; color: var(--gray-600); line-height: 1.8; }

/* ── CTA band ── */
.cta-band { background: linear-gradient(135deg, #12395e 0%, #3776ab 100%); color: var(--white); border-radius: 20px; padding: 44px 48px; display: flex; justify-content: space-between; align-items: center; gap: 32px; }
.cta-band h2 { color: var(--white); margin-top: 8px; }
.cta-band p { color: rgba(255,255,255,.78); margin-top: 12px; font-size: .92rem; }
.cta-band-badge { display: inline-block; background: var(--yellow); color: var(--navy); font-size: .72rem; font-weight: 800; padding: 3px 12px; border-radius: 20px; letter-spacing: .05em; }
.cta-band .btn-outline { border: 2px solid rgba(255,255,255,.35); color: var(--white); background: rgba(255,255,255,.08); white-space: nowrap; flex-shrink: 0; }
.cta-band .btn-outline:hover { background: rgba(255,255,255,.18); border-color: rgba(255,255,255,.6); }

/* ── CTA bottom ── */
.cta-bottom { text-align: center; padding: 80px 24px; background: var(--gray-50); }
.cta-bottom h2 { margin-bottom: 14px; }
.cta-bottom p:not(.eyebrow) { color: var(--gray-600); margin-bottom: 32px; }
.btn-group { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }

/* ── Udemy band ── */
.udemy-band { background: var(--white); border: 2px solid var(--yellow); border-radius: var(--radius); padding: 32px 36px; display: flex; align-items: center; gap: 28px; box-shadow: var(--shadow); }
.udemy-band-icon { flex-shrink: 0; width: 64px; height: 64px; border-radius: 16px; background: var(--yellow-light); display: grid; place-items: center; font-size: 30px; }
.udemy-band h3 { font-size: 1.15rem; margin-bottom: 6px; }
.udemy-band p { font-size: .9rem; color: var(--gray-600); margin: 0; }

/* ── Book card (公式テキスト紹介) ── */
.book-card { display: flex; gap: 28px; align-items: flex-start; background: var(--white); border: 1px solid var(--gray-100); border-radius: var(--radius); padding: 28px; box-shadow: var(--shadow); }
.book-cover { flex-shrink: 0; width: 140px; }
.book-cover img { width: 100%; border-radius: 6px; box-shadow: 0 4px 20px rgba(18,57,94,.18); }
.book-pr { display: inline-block; font-size: .68rem; font-weight: 800; letter-spacing: .08em; color: var(--gray-500); border: 1px solid var(--gray-300); border-radius: 4px; padding: 1px 8px; margin-bottom: 8px; }
.book-title { font-size: 1.08rem; font-weight: 800; color: var(--navy); margin-bottom: 4px; line-height: 1.5; }
.book-meta { font-size: .82rem; color: var(--gray-500); margin-bottom: 12px; }
.book-desc { font-size: .9rem; color: var(--gray-600); line-height: 1.8; margin-bottom: 16px; }
.btn-amazon { display: inline-flex; align-items: center; gap: 8px; background: #ff9900; color: #131921; font-weight: 800; font-size: .9rem; padding: 11px 22px; border-radius: 8px; transition: all .18s; }
.btn-amazon:hover { background: #e88b00; transform: translateY(-1px); }
.book-note { font-size: .76rem; color: var(--gray-500); margin-top: 14px; line-height: 1.7; }

/* ── Course guide links (各コース詳細への導線) ── */
.course-links { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.course-link-card { display: flex; align-items: center; gap: 14px; background: var(--white); border: 1px solid var(--gray-100); border-radius: 12px; padding: 18px 20px; box-shadow: var(--shadow); transition: box-shadow .16s ease, transform .16s ease; }
.course-link-card:hover { box-shadow: var(--shadow-lg); transform: translateY(-2px); }
.course-link-icon { flex-shrink: 0; width: 44px; height: 44px; border-radius: 12px; background: var(--blue-light); display: grid; place-items: center; font-size: 20px; }
.course-link-body { flex: 1; min-width: 0; }
.course-link-title { display: block; font-size: .95rem; font-weight: 800; color: var(--navy); line-height: 1.4; }
.course-link-sub { display: block; font-size: .78rem; color: var(--gray-500); margin-top: 2px; }
.course-link-arrow { flex-shrink: 0; color: var(--blue); font-weight: 900; font-size: 1.1rem; }

/* ── 学習画面イメージ ── */
.screens-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 28px 24px; }
.screen-item { margin: 0; }
.screen-item img { width: 100%; border-radius: 12px; border: 1px solid var(--gray-300); box-shadow: var(--shadow-lg); cursor: zoom-in; background: var(--white); transition: transform .2s ease; }
.screen-item img:hover { transform: scale(1.01); }
.screen-item figcaption { font-size: .85rem; color: var(--gray-600); margin-top: 10px; text-align: center; }

/* ── スマホアプリ風利用の紹介 ── */
.app-section-grid { display: grid; grid-template-columns: 1.1fr 1fr; gap: 48px; align-items: center; }
.phone-shots { display: flex; gap: 20px; justify-content: center; }
.phone-shot { margin: 0; width: min(46%, 220px); }
.phone-shot img { width: 100%; border-radius: 18px; border: 1px solid var(--gray-300); box-shadow: var(--shadow-lg); cursor: zoom-in; background: var(--white); transition: transform .2s ease; }
.phone-shot img:hover { transform: scale(1.02); }
.phone-shot figcaption { font-size: .8rem; color: var(--gray-600); margin-top: 8px; text-align: center; }
.app-steps { list-style: none; margin-top: 20px; display: flex; flex-direction: column; gap: 12px; }
.app-steps li { display: flex; gap: 12px; align-items: baseline; font-size: .95rem; color: var(--gray-600); line-height: 1.7; }
.app-step-num { flex-shrink: 0; width: 26px; height: 26px; border-radius: 50%; background: var(--blue); color: #fff; font-size: .85rem; font-weight: 700; display: inline-flex; align-items: center; justify-content: center; transform: translateY(4px); }

/* ── Lightbox ── */
.kk-lightbox { display: none; position: fixed; inset: 0; z-index: 1000; background: rgba(0,0,0,.88); align-items: center; justify-content: center; padding: 20px; }
.kk-lightbox.is-open { display: flex; }
.kk-lightbox-img { max-width: 100%; max-height: 90vh; border-radius: 8px; box-shadow: 0 16px 64px rgba(0,0,0,.5); background: #fff; }
.kk-lightbox-close { position: fixed; top: 20px; right: 24px; background: rgba(255,255,255,.15); border: none; color: #fff; font-size: 1.5rem; line-height: 1; width: 44px; height: 44px; border-radius: 50%; cursor: pointer; display: flex; align-items: center; justify-content: center; transition: background .15s; }
.kk-lightbox-close:hover { background: rgba(255,255,255,.3); }

/* ── Breadcrumb ── */
.breadcrumb { font-size: .82rem; color: var(--gray-400); margin-bottom: 20px; }
.breadcrumb a { color: var(--gray-500); text-decoration: underline; }
.breadcrumb a:hover { color: var(--navy); }

/* ── Page hero (subpages) ── */
.page-hero { background: linear-gradient(135deg, #e8f1f8 0%, #fdf8e3 100%); padding: 56px 0 48px; }

/* ── Legal page ── */
.legal-table { width: 100%; border-collapse: collapse; background: var(--white); border: 1px solid var(--gray-100); font-size: .92rem; }
.legal-table th, .legal-table td { padding: 16px 20px; border: 1px solid var(--gray-100); text-align: left; vertical-align: top; line-height: 1.8; }
.legal-table th { background: var(--gray-50); color: var(--navy); font-weight: 700; width: 28%; white-space: nowrap; }
.legal-table ul { padding-left: 1.2em; }

/* ── Footer ── */
.kk-footer { background: var(--gray-50); border-top: 1px solid var(--gray-100); color: var(--gray-600); padding: 44px 0 0; }
.kk-footer-inner { display: flex; justify-content: space-between; align-items: flex-start; gap: 32px; flex-wrap: wrap; }
.kk-footer .kk-brand { color: var(--navy); }
.kk-footer .kk-brand-sub { color: var(--blue); }
.kk-footer-links { display: flex; flex-wrap: wrap; gap: 14px; font-size: .85rem; align-items: flex-start; }
.kk-footer-links a { color: var(--gray-600); }
.kk-footer-links a:hover { color: var(--navy); }
.kk-footer-studio-link { color: var(--blue); text-decoration: underline; }
.kk-copyright { margin-top: 28px; font-size: .78rem; border-top: 1px solid var(--gray-100); padding: 18px 0; text-align: center; color: var(--gray-400); }

/* ── Responsive ── */
@media (max-width: 1024px) {
  .price-grid { grid-template-columns: 1fr 1fr; }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .section { padding: 56px 0; }
  .grid-2, .grid-3, .price-grid { grid-template-columns: 1fr; }
  .stats-bar { grid-template-columns: repeat(2, 1fr); }
  .price-card-featured { order: -1; }
  .cta-band { flex-direction: column; align-items: flex-start; padding: 28px 28px; }
  .instructor { grid-template-columns: 1fr; }
  .instructor-photo { max-width: 220px; }
  .udemy-band { flex-direction: column; align-items: flex-start; gap: 16px; padding: 24px; }
  .book-card { flex-direction: column; }
  .book-cover { width: 120px; margin: 0 auto; }
  .course-links { grid-template-columns: 1fr; }
  .screens-grid { grid-template-columns: 1fr; }
  .app-section-grid { grid-template-columns: 1fr; gap: 32px; }
  .kk-nav {
    display: none;
    position: absolute; top: 64px; left: 0; right: 0;
    background: var(--white); flex-direction: column; align-items: flex-start;
    padding: 16px 24px; gap: 16px;
    border-bottom: 1px solid var(--gray-100);
    box-shadow: 0 4px 12px rgba(0,0,0,.08);
  }
  .kk-nav.is-open { display: flex; }
  .kk-nav-toggle { display: flex; }
  .kk-footer-inner { flex-direction: column; }
  .kk-footer-links { flex-direction: row; flex-wrap: wrap; gap: 16px; }
}

@media (max-width: 480px) {
  .hero-actions { flex-direction: column; }
  .btn-group { flex-direction: column; align-items: center; }
  .cta-band { padding: 28px 20px; }
  .grid-4 { grid-template-columns: 1fr; }
  .stats-bar { grid-template-columns: repeat(2, 1fr); gap: 10px; }
}

/* ── Back to top ── */
.back-to-top {
  position: fixed; right: 20px; bottom: 24px; z-index: 90;
  width: 46px; height: 46px; border-radius: 50%; border: none; cursor: pointer;
  background: var(--blue); color: var(--white);
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 4px 14px rgba(0,0,0,.22);
  opacity: 0; visibility: hidden; transform: translateY(10px);
  transition: opacity .25s, visibility .25s, transform .25s, background .2s;
}
.back-to-top.is-visible { opacity: 1; visibility: visible; transform: translateY(0); }
.back-to-top:hover { background: var(--blue-dark); }
.back-to-top svg { width: 20px; height: 20px; }
@media (max-width: 480px) {
  .back-to-top { right: 14px; bottom: 18px; width: 42px; height: 42px; }
}