:root {
  --bg: #ffffff;
  --bg-secondary: #f5f5f7;
  --bg-card: #ffffff;
  --text-primary: #1d1d1f;
  --text-secondary: #6e6e73;
  --text-tertiary: #a1a1a6;
  --accent: #0071e3;
  --accent-hover: #0077ed;
  --border: #d2d2d7;
  --border-light: #e8e8ed;
  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
  --shadow-hover: 0 8px 40px rgba(0, 0, 0, 0.12);
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* ───── HEADER ───── */
header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--border-light);
}

nav {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 24px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.3px;
}

.nav-logo span {
  color: var(--accent);
}

.nav-links {
  display: flex;
  gap: 28px;
  list-style: none;
}

.nav-links a {
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 400;
  transition: color 0.2s;
}

.nav-links a:hover {
  color: var(--text-primary);
  text-decoration: none;
}

/* ───── HERO ───── */
.hero {
  background: var(--bg-secondary);
  padding: 96px 24px 80px;
  text-align: center;
}

.hero-eyebrow {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 16px;
}

.hero h1 {
  font-size: clamp(36px, 5vw, 60px);
  font-weight: 700;
  letter-spacing: -1.5px;
  line-height: 1.1;
  color: var(--text-primary);
  margin-bottom: 20px;
}

.hero p {
  font-size: 18px;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto 36px;
  line-height: 1.6;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 12px 28px;
  border-radius: 980px;
  font-size: 15px;
  font-weight: 500;
  transition: all 0.2s;
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover {
  background: var(--accent-hover);
  text-decoration: none;
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(0, 113, 227, 0.3);
}

.btn-secondary {
  background: transparent;
  color: var(--accent);
  border: 1.5px solid var(--accent);
}

.btn-secondary:hover {
  background: rgba(0, 113, 227, 0.06);
  text-decoration: none;
}

/* ───── SECTIONS ───── */
section {
  max-width: 1080px;
  margin: 0 auto;
  padding: 80px 24px;
}

.section-label {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 12px;
}

h2 {
  font-size: clamp(28px, 3vw, 40px);
  font-weight: 700;
  letter-spacing: -0.8px;
  color: var(--text-primary);
  margin-bottom: 16px;
}

h3 {
  font-size: 20px;
  font-weight: 600;
  letter-spacing: -0.3px;
  margin-bottom: 8px;
}

.text-secondary {
  color: var(--text-secondary);
}

/* ───── APP CARDS ───── */
.app-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
  margin-top: 48px;
}

.app-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  padding: 36px 32px;
  transition: all 0.25s;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
}

.app-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
  text-decoration: none;
}

.app-icon {
  width: 64px;
  height: 64px;
  border-radius: 16px;
  margin-bottom: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 30px;
}

.app-icon-scheduler {
  background: linear-gradient(135deg, #5856d6, #007aff);
}

.app-icon-toeic {
  background: linear-gradient(135deg, #ff6b35, #ff9500);
}

.app-card h3 {
  color: var(--text-primary);
}

.app-card p {
  color: var(--text-secondary);
  font-size: 15px;
  line-height: 1.6;
  margin-bottom: 24px;
  flex: 1;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: auto;
}

.tag {
  padding: 4px 10px;
  background: var(--bg-secondary);
  border-radius: 980px;
  font-size: 12px;
  font-weight: 500;
  color: var(--text-secondary);
}

/* ───── FEATURE GRID ───── */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
  margin-top: 40px;
}

.feature-item {
  padding: 28px 24px;
  background: var(--bg-secondary);
  border-radius: var(--radius);
}

.feature-icon {
  font-size: 28px;
  margin-bottom: 12px;
}

.feature-item h4 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 6px;
}

.feature-item p {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* ───── APP DETAIL HERO ───── */
.app-hero {
  padding: 80px 24px 64px;
  background: var(--bg-secondary);
  text-align: center;
}

.app-hero-icon {
  width: 96px;
  height: 96px;
  border-radius: 22px;
  margin: 0 auto 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 44px;
}

.app-hero h1 {
  font-size: clamp(28px, 4vw, 48px);
  font-weight: 700;
  letter-spacing: -1px;
  margin-bottom: 16px;
}

.app-hero p {
  font-size: 18px;
  color: var(--text-secondary);
  max-width: 520px;
  margin: 0 auto 32px;
}

/* ───── ABOUT ───── */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
}

.about-content h2 {
  margin-bottom: 20px;
}

.about-content p {
  color: var(--text-secondary);
  font-size: 16px;
  line-height: 1.8;
  margin-bottom: 16px;
}

.info-table {
  background: var(--bg-secondary);
  border-radius: var(--radius);
  overflow: hidden;
}

.info-row {
  display: flex;
  padding: 16px 24px;
  border-bottom: 1px solid var(--border-light);
  font-size: 15px;
}

.info-row:last-child {
  border-bottom: none;
}

.info-label {
  width: 120px;
  flex-shrink: 0;
  font-weight: 500;
  color: var(--text-secondary);
  font-size: 13px;
}

.info-value {
  color: var(--text-primary);
}

/* ───── SUPPORT FORM ───── */
.form-group {
  margin-bottom: 20px;
}

label {
  display: block;
  font-size: 13px;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

input, select, textarea {
  width: 100%;
  padding: 12px 16px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-family: inherit;
  color: var(--text-primary);
  background: var(--bg);
  transition: border-color 0.2s;
  outline: none;
}

input:focus, select:focus, textarea:focus {
  border-color: var(--accent);
}

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

.form-max {
  max-width: 560px;
}

/* ───── PRIVACY ───── */
.prose {
  max-width: 720px;
}

.prose h2 {
  font-size: 24px;
  margin-top: 48px;
  margin-bottom: 12px;
}

.prose h3 {
  font-size: 18px;
  margin-top: 28px;
  margin-bottom: 8px;
}

.prose p, .prose li {
  font-size: 15px;
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 12px;
}

.prose ul, .prose ol {
  padding-left: 20px;
  margin-bottom: 16px;
}

.prose li {
  margin-bottom: 6px;
}

/* ───── FOOTER ───── */
footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-light);
  padding: 48px 24px 36px;
}

.footer-inner {
  max-width: 1080px;
  margin: 0 auto;
}

.footer-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 32px;
  flex-wrap: wrap;
  gap: 32px;
}

.footer-brand .nav-logo {
  font-size: 20px;
  margin-bottom: 8px;
  display: block;
}

.footer-brand p {
  font-size: 13px;
  color: var(--text-tertiary);
  max-width: 240px;
  line-height: 1.6;
}

.footer-links-group h4 {
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.footer-links-group ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.footer-links-group a {
  font-size: 13px;
  color: var(--text-secondary);
  transition: color 0.2s;
}

.footer-links-group a:hover {
  color: var(--text-primary);
  text-decoration: none;
}

.footer-bottom {
  border-top: 1px solid var(--border-light);
  padding-top: 24px;
  font-size: 12px;
  color: var(--text-tertiary);
  line-height: 1.8;
}

.footer-bottom p + p {
  margin-top: 4px;
}

/* ───── DIVIDER ───── */
.divider {
  border: none;
  border-top: 1px solid var(--border-light);
  margin: 0;
}

/* ───── BADGE ───── */
.badge {
  display: inline-block;
  padding: 4px 12px;
  border-radius: 980px;
  font-size: 12px;
  font-weight: 600;
  margin-bottom: 16px;
}

.badge-blue {
  background: rgba(0, 113, 227, 0.1);
  color: var(--accent);
}

.badge-orange {
  background: rgba(255, 149, 0, 0.12);
  color: #b35900;
}

/* ───── LANG TOGGLE ───── */
.lang-toggle {
  display: flex;
  align-items: center;
  gap: 2px;
  background: var(--bg-secondary);
  border-radius: 980px;
  padding: 3px;
  border: 1px solid var(--border-light);
}

.lang-btn {
  padding: 4px 10px;
  border-radius: 980px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.04em;
  cursor: pointer;
  border: none;
  background: transparent;
  color: var(--text-tertiary);
  transition: all 0.18s;
}

.lang-btn.active {
  background: var(--bg-card);
  color: var(--text-primary);
  box-shadow: 0 1px 4px rgba(0,0,0,0.1);
}

.lang-btn:hover:not(.active) {
  color: var(--text-secondary);
}

/* ───── RESPONSIVE ───── */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .footer-top {
    flex-direction: column;
    gap: 24px;
  }

  section {
    padding: 60px 20px;
  }

  .hero {
    padding: 72px 20px 60px;
  }
}