:root {
  --ink: #2d4084;
  --ink-sub: #6b7a95;
  --line: #e3e8f0;
  --bg: #ffffff;
}

* {
  box-sizing: border-box;
}
html,
body {
  margin: 0;
}

body {
  font-family: "Noto Sans JP", sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}

.wrap {
  max-width: 880px;
  margin: 0 auto;
  padding: 80px 48px 120px;
}

/* ========== HEADER ========== */
header {
  padding-bottom: 40px;
  border-bottom: 1px solid var(--line);
}
header .kicker {
  font-size: 15px;
  color: var(--ink-sub);
  letter-spacing: 0.05em;
}
header h1 {
  margin: 8px 0 6px;
  font-size: 44px;
  font-weight: 700;
  line-height: 1.3;
}
header .sub {
  font-size: 17px;
  color: var(--ink-sub);
}

/* ========== EXTERNAL TOOLS ========== */
.tools {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin: 40px 0 64px;
}
.tool {
  display: block;
  padding: 20px 22px;
  border: 1px solid var(--line);
  text-decoration: none;
  color: var(--ink);
  transition: border-color 0.15s;
}
.tool:hover {
  border-color: var(--ink);
}
.tool .label {
  font-size: 13px;
  color: var(--ink-sub);
  letter-spacing: 0.1em;
}
.tool .name {
  margin-top: 4px;
  font-size: 20px;
  font-weight: 700;
}
.tool .arrow {
  margin-top: 14px;
  font-size: 15px;
  color: var(--ink-sub);
}
.tool:hover .arrow {
  color: var(--ink);
}

/* ========== SECTION HEAD ========== */
.sec-head {
  display: flex;
  align-items: baseline;
  gap: 16px;
  margin-bottom: 20px;
}
.sec-head h2 {
  margin: 0;
  font-size: 24px;
  font-weight: 700;
}
.sec-head .rule {
  flex: 1;
  height: 1px;
  background: var(--line);
}
.sec-head .count {
  font-size: 13px;
  color: var(--ink-sub);
}

/* ========== SESSION ========== */
.session {
  padding: 24px 0;
  border-bottom: 1px solid var(--line);
  display: grid;
  grid-template-columns: 64px 1fr auto;
  gap: 24px;
  align-items: center;
}
.session .no {
  font-size: 38px;
  font-weight: 700;
  color: var(--ink);
  line-height: 1;
  font-variant-numeric: tabular-nums;
}
.session .meta .date {
  font-size: 14px;
  color: var(--ink-sub);
  margin-bottom: 4px;
}
.session .meta .title {
  font-size: 20px;
  font-weight: 500;
}
.session .meta .desc {
  font-size: 14px;
  color: var(--ink-sub);
  margin-top: 4px;
}
.session .actions {
  display: flex;
  gap: 8px;
}

/* ========== BUTTONS ========== */
.btn {
  display: inline-flex;
  align-items: center;
  padding: 12px 18px;
  font-size: 15px;
  font-weight: 500;
  text-decoration: none;
  border: 1px solid var(--ink);
  color: var(--ink);
  background: transparent;
  transition: background 0.15s, color 0.15s;
  white-space: nowrap;
}
.btn:hover {
  background: var(--ink);
  color: #fff;
}
.btn.primary {
  background: var(--ink);
  color: #fff;
}
.btn.primary:hover {
  background: #16213f;
}

/* ========== FOOTER ========== */
footer {
  margin-top: 80px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  font-size: 13px;
  color: var(--ink-sub);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
}

/* ========== MOBILE ========== */
@media (max-width: 680px) {
  .wrap {
    padding: 48px 24px 80px;
  }
  header h1 {
    font-size: 32px;
  }
  .tools {
    grid-template-columns: 1fr;
  }
  .session {
    grid-template-columns: 52px 1fr;
    grid-template-rows: auto auto;
    gap: 8px 16px;
  }
  .session .actions {
    grid-column: 1 / -1;
    flex-wrap: wrap;
    margin-top: 8px;
  }
}