:root {
  --navy: #102c4c;
  --blue: #1769aa;
  --blue-light: #eaf4fb;
  --orange: #ef7b2d;
  --green: #16865b;
  --text: #263442;
  --muted: #627181;
  --line: #dce5ec;
  --background: #f4f7f9;
  --white: #ffffff;
  --content-width: 1180px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 90px;
}

body {
  margin: 0;
  color: var(--text);
  background: var(--background);
  font-family: "Yu Gothic", "Hiragino Kaku Gothic ProN", "Noto Sans JP", sans-serif;
  font-size: 16px;
  line-height: 1.8;
}

a {
  color: inherit;
  text-decoration: none;
}

img {
  max-width: 100%;
  height: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.96);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  width: min(calc(100% - 40px), var(--content-width));
  min-height: 76px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
}

.site-logo {
  display: flex;
  align-items: center;
}

.site-logo img {
  display: block;
  width: 174px;
}

.header-message {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 18px;
  color: var(--navy);
}

.header-message span {
  padding-left: 18px;
  color: var(--muted);
  border-left: 1px solid var(--line);
  font-size: 14px;
}

.menu-button {
  display: none;
}

.contact-hero {
  color: var(--white);
  background:
    linear-gradient(115deg, rgba(11, 41, 72, 0.98), rgba(20, 91, 139, 0.92)),
    linear-gradient(45deg, #102c4c, #1769aa);
}

.contact-hero-inner {
  width: min(calc(100% - 40px), var(--content-width));
  min-height: 420px;
  margin: 0 auto;
  padding: 64px 0;
  display: flex;
  align-items: center;
}

.hero-kicker,
.section-label {
  margin: 0 0 10px;
  color: var(--orange);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.14em;
}

.hero-copy h1 {
  max-width: 980px;
  margin: 0 0 24px;
  font-size: clamp(32px, 3.6vw, 48px);
  line-height: 1.35;
  letter-spacing: 0.02em;
}

.hero-description {
  max-width: 650px;
  margin: 0;
  color: #dce9f3;
  font-size: 17px;
}

.language-tags {
  margin-top: 28px;
  display: flex;
  gap: 10px;
}

.language-tags span {
  padding: 5px 14px;
  border: 1px solid rgba(255, 255, 255, 0.35);
  border-radius: 20px;
  font-size: 13px;
}

.page-layout {
  width: min(calc(100% - 40px), var(--content-width));
  margin: 52px auto 80px;
  display: grid;
  grid-template-columns: 250px minmax(0, 1fr);
  align-items: start;
  gap: 42px;
}

.side-navigation {
  position: sticky;
  top: 104px;
}

.side-navigation-inner {
  padding: 22px;
  background: var(--white);
  border-top: 4px solid var(--blue);
  box-shadow: 0 6px 22px rgba(20, 45, 68, 0.08);
}

.side-title {
  margin: 0 0 4px;
  color: var(--navy);
  font-size: 17px;
  font-weight: 700;
}

.side-description {
  margin: 0 0 18px;
  color: var(--muted);
  font-size: 11px;
  line-height: 1.65;
}

.side-navigation nav {
  display: grid;
}

.side-navigation nav a {
  padding: 9px 0 9px 12px;
  color: var(--muted);
  border-left: 2px solid var(--line);
  font-size: 14px;
}

.side-navigation nav a:hover,
.side-navigation nav a.active {
  color: var(--blue);
  border-left-color: var(--blue);
  font-weight: 700;
}

.side-navigation nav .article-list-link {
  margin-bottom: 10px;
  padding: 13px 14px;
  display: grid;
  gap: 4px;
  color: var(--text);
  background: var(--blue-light);
  border: 1px solid #cfe2ef;
  border-left: 3px solid var(--blue);
}

.side-navigation nav .article-list-link.current {
  background: #dceffb;
  border-color: #a9cfe6;
}

.article-list-link strong {
  color: var(--navy);
  font-size: 14px;
}

.article-list-link span {
  color: var(--muted);
  font-size: 11px;
  font-weight: 400;
  line-height: 1.6;
}

.side-navigation nav .side-contact-link {
  margin-top: 15px;
  padding: 10px 12px;
  color: var(--white);
  text-align: center;
  background: var(--blue);
  border: 0;
  border-radius: 4px;
}

.side-note {
  margin-top: 22px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.side-note strong {
  color: var(--navy);
  font-size: 13px;
}

.side-note p {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.7;
}

.article-content {
  min-width: 0;
}

.article-intro {
  padding: 42px;
  background: var(--white);
  border-left: 5px solid var(--orange);
  box-shadow: 0 6px 22px rgba(20, 45, 68, 0.08);
}

.article-intro h2,
.article-section h2 {
  margin: 0 0 14px;
  color: var(--navy);
  line-height: 1.5;
}

.article-intro h2 {
  font-size: clamp(25px, 3vw, 34px);
}

.article-intro p:last-child {
  color: var(--muted);
}

.article-tags {
  margin-top: 22px;
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}

.article-tags span {
  padding: 4px 10px;
  color: var(--blue);
  background: var(--blue-light);
  border-radius: 20px;
  font-size: 11px;
  font-weight: 700;
}

.article-section {
  position: relative;
  margin-top: 25px;
  padding: 42px;
  background: var(--white);
  border: 1px solid #e7edf1;
}

.article-section .section-label {
  color: var(--blue);
}

.article-section h2 {
  margin-bottom: 22px;
  font-size: 25px;
}

.article-section h3 {
  margin: 32px 0 14px;
  color: var(--navy);
  font-size: 20px;
}

.article-section p {
  margin: 0 0 20px;
}

.article-section p:last-child {
  margin-bottom: 0;
}

.stats-grid {
  margin: 28px 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.stats-grid div {
  padding: 20px;
  display: grid;
  gap: 3px;
  background: var(--blue-light);
  border-left: 3px solid var(--blue);
}

.stats-grid strong {
  color: var(--navy);
  font-size: 22px;
}

.stats-grid span {
  color: var(--muted);
  font-size: 12px;
}

.article-figure {
  margin: 30px 0;
  overflow: hidden;
}

.article-figure img {
  width: 100%;
  height: auto;
  display: block;
  border: 1px solid var(--line);
}

.article-figure figcaption {
  padding: 9px 12px;
  color: var(--muted);
  background: #f7f9fa;
  font-size: 11px;
}

.table-scroll {
  margin: 24px 0;
  overflow-x: auto;
}

.table-scroll table {
  width: 100%;
  min-width: 560px;
  border-collapse: collapse;
}

.table-scroll th,
.table-scroll td {
  padding: 12px 14px;
  text-align: left;
  border: 1px solid var(--line);
}

.table-scroll th {
  color: var(--white);
  background: var(--navy);
  font-size: 13px;
}

.table-scroll td {
  background: var(--white);
  font-size: 14px;
}

.table-scroll td:last-child {
  text-align: left;
}

.table-emphasis td {
  color: var(--navy);
  background: var(--blue-light);
  font-weight: 700;
}

.calculation-box {
  margin: 24px 0;
  padding: 20px;
  display: grid;
  gap: 4px;
  color: var(--navy);
  text-align: center;
  background: var(--blue-light);
  border: 1px solid #cfe2ef;
}

.calculation-box strong {
  font-size: 21px;
}

.calculation-box span {
  color: var(--muted);
  font-size: 13px;
}

.article-note {
  padding: 15px 17px;
  color: var(--muted);
  background: #f7f9fa;
  border-left: 3px solid var(--orange);
  font-size: 12px;
}

.problem-list,
.future-topics {
  margin: 24px 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  list-style: none;
}

.problem-list li,
.future-topics li {
  padding: 13px 15px 13px 34px;
  position: relative;
  background: #f7f9fa;
  border: 1px solid var(--line);
  font-size: 13px;
}

.problem-list li::before,
.future-topics li::before {
  position: absolute;
  top: 13px;
  left: 14px;
  color: var(--blue);
  content: "✓";
  font-weight: 700;
}

.reason-list {
  margin: 28px 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
  counter-reset: reason;
  list-style: none;
}

.reason-list li {
  padding: 20px 20px 20px 64px;
  position: relative;
  background: #f7f9fa;
  border: 1px solid var(--line);
  counter-increment: reason;
}

.reason-list li::before {
  position: absolute;
  top: 19px;
  left: 20px;
  color: var(--blue);
  content: counter(reason, decimal-leading-zero);
  font-size: 18px;
  font-weight: 700;
}

.reason-list strong {
  color: var(--navy);
}

.reason-list p {
  margin: 5px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.article-cta {
  margin-top: 25px;
  padding: 42px;
  color: var(--white);
  background: var(--navy);
}

.article-cta h2 {
  margin: 0 0 16px;
  color: var(--white);
  font-size: 27px;
  line-height: 1.5;
}

.article-cta p {
  margin: 0 0 12px;
  color: #d8e4ed;
}

.article-cta a {
  margin-top: 12px;
  padding: 12px 22px;
  display: inline-block;
  color: var(--white);
  background: var(--orange);
  border-radius: 4px;
  font-weight: 700;
}

.topic-grid {
  margin: 23px 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.topic-card {
  padding: 18px;
  display: grid;
  gap: 3px;
  background: var(--blue-light);
  border-radius: 5px;
}

.topic-card strong {
  color: var(--navy);
}

.topic-card span {
  color: var(--muted);
  font-size: 13px;
}

.contact-section {
  padding: 72px 20px;
  background: var(--white);
  border-top: 1px solid var(--line);
}

.contact-section-inner {
  width: min(100%, var(--content-width));
  margin: 0 auto;
}

.contact-heading {
  max-width: 760px;
  margin-bottom: 28px;
}

.contact-heading h2,
.simple-contact h2 {
  margin: 0 0 10px;
  color: var(--navy);
  font-size: clamp(27px, 3vw, 36px);
  line-height: 1.45;
}

.contact-heading p:last-child,
.simple-contact-intro > p:not(.section-label) {
  margin: 0;
  color: var(--muted);
}

.contact-methods {
  margin-bottom: 42px;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.contact-method {
  padding: 20px 22px;
  display: grid;
  gap: 3px;
  background: var(--blue-light);
  border: 1px solid #cfe2ef;
  border-radius: 5px;
}

a.contact-method:hover {
  border-color: var(--blue);
}

.contact-method span {
  color: var(--blue);
  font-size: 13px;
  font-weight: 700;
}

.contact-method strong {
  color: var(--navy);
  overflow-wrap: anywhere;
}

.simple-contact {
  padding: 42px;
  display: grid;
  grid-template-columns: minmax(240px, 0.7fr) minmax(0, 1.3fr);
  align-items: start;
  gap: 48px;
  background: var(--background);
  border-top: 4px solid var(--blue);
}

.simple-contact-intro {
  position: sticky;
  top: 104px;
}

.simple-contact-intro .form-note {
  margin-top: 22px;
  padding: 13px 15px;
  color: var(--muted);
  background: var(--white);
  border-left: 3px solid var(--orange);
  font-size: 12px;
}

.contact-form {
  padding: 30px;
  background: var(--white);
  border: 1px solid var(--line);
}

.form-row {
  margin-bottom: 22px;
}

.form-row label {
  margin-bottom: 7px;
  display: block;
  color: var(--navy);
  font-weight: 700;
}

.form-row label span {
  margin-left: 7px;
  padding: 2px 6px;
  color: var(--white);
  background: var(--orange);
  border-radius: 2px;
  font-size: 10px;
}

.form-row input,
.form-row textarea {
  width: 100%;
  padding: 11px 12px;
  color: var(--text);
  background: var(--white);
  border: 1px solid #bfcbd4;
  border-radius: 3px;
  font: inherit;
}

.form-row input:focus,
.form-row textarea:focus {
  outline: 2px solid rgba(23, 105, 170, 0.2);
  border-color: var(--blue);
}

.captcha-input {
  display: grid;
  grid-template-columns: 150px minmax(0, 1fr);
  align-items: center;
  gap: 12px;
}

.captcha-input strong {
  padding: 11px;
  color: var(--navy);
  text-align: center;
  background: var(--blue-light);
  border: 1px solid #cfe2ef;
}

.captcha-row p {
  margin: 5px 0 0;
  color: var(--muted);
  font-size: 12px;
}

.submit-button {
  width: 100%;
  padding: 14px 20px;
  color: var(--white);
  background: var(--orange);
  border: 0;
  border-radius: 4px;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}

.submit-button:hover {
  background: #db6920;
}

.submit-button:disabled {
  cursor: wait;
  opacity: 0.65;
}

.contact-honeypot {
  position: absolute !important;
  left: -10000px !important;
  width: 1px !important;
  height: 1px !important;
  overflow: hidden !important;
}

.form-status {
  min-height: 1.8em;
  margin: 12px 0 0;
  font-size: 13px;
  font-weight: 700;
}

.form-status.error {
  color: #b53a2d;
}

.form-status.success {
  color: var(--green);
}

.site-footer {
  padding: 32px max(20px, calc((100% - var(--content-width)) / 2));
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 30px;
  color: #bac6d0;
  background: #0a2239;
  font-size: 12px;
}

.site-footer div {
  display: flex;
  align-items: center;
  gap: 18px;
}

.site-footer img {
  width: 120px;
  padding: 4px;
  background: var(--white);
  border-radius: 3px;
}

.site-footer p {
  margin: 0;
}

@media screen and (max-width: 900px) {
  .header-message {
    display: none;
  }

  .menu-button {
    width: 48px;
    height: 48px;
    padding: 8px;
    display: grid;
    place-content: center;
    gap: 5px;
    color: var(--navy);
    background: transparent;
    border: 0;
  }

  .menu-button span:not(.menu-label) {
    width: 24px;
    height: 2px;
    display: block;
    background: var(--navy);
  }

  .menu-label {
    font-size: 9px;
  }

  .page-layout {
    display: block;
  }

  .side-navigation {
    position: fixed;
    z-index: 99;
    top: 76px;
    right: 0;
    bottom: 0;
    width: min(84vw, 330px);
    padding: 18px;
    overflow-y: auto;
    background: var(--background);
    box-shadow: -12px 0 25px rgba(10, 34, 57, 0.18);
    transform: translateX(110%);
    transition: transform 0.25s ease;
  }

  .side-navigation.open {
    transform: translateX(0);
  }

  .article-section {
    margin-top: 18px;
  }

  .simple-contact {
    grid-template-columns: 1fr;
    gap: 30px;
  }

  .simple-contact-intro {
    position: static;
  }
}

@media screen and (max-width: 600px) {
  body {
    font-size: 15px;
  }

  .header-inner,
  .contact-hero-inner,
  .page-layout {
    width: min(calc(100% - 28px), var(--content-width));
  }

  .header-inner {
    min-height: 68px;
  }

  .site-logo img {
    width: 140px;
  }

  .contact-hero-inner {
    min-height: auto;
    padding: 42px 0;
  }

  .hero-copy h1 {
    font-size: 30px;
  }

  .hero-description {
    font-size: 15px;
  }

  .page-layout {
    margin-top: 24px;
    margin-bottom: 45px;
  }

  .article-intro,
  .article-section {
    padding: 25px 22px;
  }

  .article-section h2 {
    font-size: 21px;
  }

  .stats-grid,
  .problem-list,
  .future-topics {
    grid-template-columns: 1fr;
  }

  .article-cta {
    padding: 28px 22px;
  }

  .article-cta h2 {
    font-size: 22px;
  }

  .contact-section {
    padding: 48px 14px;
  }

  .contact-methods {
    grid-template-columns: 1fr;
  }

  .simple-contact,
  .contact-form {
    padding: 24px 20px;
  }

  .captcha-input {
    grid-template-columns: 1fr;
  }

  .site-footer,
  .site-footer div {
    align-items: flex-start;
    flex-direction: column;
  }
}