/* =========================
  全体（グラスモーフィズム + グラデーション）
========================= */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif;
  background: #000;
  color: #fff;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  position: relative;
  overflow-x: hidden;
  padding: 2rem 0;
}

/* 動的背景グラデーション */
body::before {
  content: "";
  position: fixed;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle at 20% 50%,
      rgba(0, 198, 255, 0.15) 0%,
      transparent 50%),
    radial-gradient(circle at 80% 80%,
      rgba(255, 76, 76, 0.1) 0%,
      transparent 50%);
  animation: gradientShift 15s ease infinite;
  pointer-events: none;
  z-index: 0;
}

@keyframes gradientShift {

  0%,
  100% {
    transform: translate(0, 0) rotate(0deg);
  }

  50% {
    transform: translate(-5%, -5%) rotate(180deg);
  }
}

/* グリッド背景 */
body::after {
  content: "";
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.02) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.02) 1px, transparent 1px);
  background-size: 50px 50px;
  pointer-events: none;
  z-index: 0;
}

/* コンテンツをz-indexで前面に */
header,
form,
ul,
.tabs,
#registerSection,
#loginSection {
  position: relative;
  z-index: 1;
}

/* =========================
  ヘッダー
========================= */
header {
  display: flex;
  flex-direction: column;
  align-items: center;
  max-width: 900px;
  text-align: center;
  margin: 60px 20px 40px;
}

h1 {
  font-size: 3.5rem;
  font-weight: 800;
  background: linear-gradient(135deg, #00c6ff 0%, #0072ff 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 30px;
  letter-spacing: -2px;
  text-shadow: 0 0 40px rgba(0, 198, 255, 0.3);
}

.user-info {
  display: flex;
  align-items: center;
  gap: 24px;
  margin-bottom: 40px;
  padding: 20px 40px;
  background: rgba(255, 255, 255, 0.05);
  backdrop-filter: blur(20px);
  border-radius: 50px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
}

#userName {
  font-size: 2rem;
  font-weight: 700;
  color: #fff;
  position: relative;
  letter-spacing: -0.5px;
}

#userName::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -8px;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, #00c6ff, transparent);
  border-radius: 2px;
  box-shadow: 0 0 10px rgba(0, 198, 255, 0.5);
}

#logout {
  background: linear-gradient(135deg, #ff4c4c 0%, #ff1744 100%);
  color: #fff;
  padding: 12px 28px;
  border-radius: 50px;
  border: none;
  cursor: pointer;
  font-size: 1rem;
  font-weight: 600;
  box-shadow: 0 8px 20px rgba(255, 76, 76, 0.3);
  transition: all 0.3s cubic-bezier(0.23, 1, 0.32, 1);
}

#logout:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 30px rgba(255, 76, 76, 0.5);
}

#logout:active {
  transform: translateY(0);
}

/* =========================
  フォーム（ガラスモーフィズム）
========================= */
form {
  background: rgba(255, 255, 255, 0.05);
  backdrop-filter: blur(20px);
  padding: 40px;
  border-radius: 24px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  max-width: 600px;
  width: calc(100% - 40px);
  margin: 0 20px 40px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

textarea,
input {
  width: 100%;
  padding: 16px 20px;
  border-radius: 16px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  background: rgba(255, 255, 255, 0.05);
  color: #fff;
  font-size: 1rem;
  transition: all 0.3s ease;
}

textarea::placeholder,
input::placeholder {
  color: rgba(255, 255, 255, 0.4);
}

textarea:focus,
input:focus {
  outline: none;
  border-color: #00c6ff;
  background: rgba(255, 255, 255, 0.08);
  box-shadow: 0 0 20px rgba(0, 198, 255, 0.2);
}

/* =========================
  ボタン（モダン）
========================= */
button {
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
  padding: 14px 24px;
  border-radius: 16px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  cursor: pointer;
  font-size: 1rem;
  font-weight: 600;
  backdrop-filter: blur(10px);
  transition: all 0.3s cubic-bezier(0.23, 1, 0.32, 1);
}

button:hover {
  background: rgba(255, 255, 255, 0.15);
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.2);
}

button:active {
  transform: translateY(0);
}

/* =========================
  投稿一覧
========================= */
ul {
  list-style: none;
  max-width: 700px;
  width: calc(100% - 40px);
  display: flex;
  flex-direction: column;
  gap: 24px;
  margin: 0 20px;
}

li {
  background: rgba(255, 255, 255, 0.05);
  backdrop-filter: blur(20px);
  padding: 24px;
  border-radius: 20px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
  transition: all 0.3s cubic-bezier(0.23, 1, 0.32, 1);
}

li:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.3);
  border-color: rgba(255, 255, 255, 0.2);
}

li .post-meta {
  text-align: right;
  color: rgba(255, 255, 255, 0.5);
  font-size: 0.9rem;
  margin-top: 12px;
}

/* =========================
  ハートボタン
========================= */
button.heart {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid rgba(255, 255, 255, 0.1);
  background: rgba(255, 255, 255, 0.05);
  cursor: pointer;
  position: relative;
  transition: all 0.3s cubic-bezier(0.23, 1, 0.32, 1);
}

button.heart:hover {
  background: rgba(255, 76, 76, 0.1);
  transform: scale(1.1);
}

button.heart::before {
  content: "♡";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 1.4rem;
  color: #ff4c4c;
  transition: all 0.3s ease;
}

button.heart.favorited::before {
  content: "❤️";
  animation: heartBeat 0.6s ease;
}

@keyframes heartBeat {

  0%,
  100% {
    transform: translate(-50%, -50%) scale(1);
  }

  25% {
    transform: translate(-50%, -50%) scale(1.3);
  }

  50% {
    transform: translate(-50%, -50%) scale(1.1);
  }

  75% {
    transform: translate(-50%, -50%) scale(1.2);
  }
}

/* =========================
  タブ（モダン）
========================= */
.tabs {
  display: flex;
  justify-content: center;
  gap: 16px;
  margin: 40px 20px 30px;
}

.tab {
  padding: 12px 32px;
  border-radius: 50px;
  background: rgba(255, 255, 255, 0.05);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.1);
  cursor: pointer;
  font-weight: 600;
  color: rgba(255, 255, 255, 0.7);
  transition: all 0.3s cubic-bezier(0.23, 1, 0.32, 1);
}

.tab:hover {
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
}

.tab.active {
  background: linear-gradient(135deg, #00c6ff 0%, #0072ff 100%);
  color: #fff;
  border-color: transparent;
  box-shadow: 0 8px 20px rgba(0, 198, 255, 0.3);
}

/* =========================
  登録・ログインフォーム
========================= */
#registerSection,
#loginSection {
  text-align: center;
  padding: 40px 20px;
}

#registerSection>h2,
#loginSection>h2 {
  font-size: 3rem;
  margin-bottom: 40px;
  background: linear-gradient(135deg, #fff 0%, rgba(255, 255, 255, 0.6) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  font-weight: 800;
  letter-spacing: -1px;
}

#regName,
#regEmail,
#regPassword,
#loginEmail,
#loginPassword {
  height: 56px;
  font-size: 1rem;
}

/* =========================
  レスポンシブ
========================= */
@media (max-width: 768px) {
  h1 {
    font-size: 2.5rem;
  }

  .user-info {
    flex-direction: column;
    gap: 16px;
    padding: 20px 30px;
  }

  #userName {
    font-size: 1.8rem;
  }

  form {
    padding: 30px 24px;
  }
}

@media (max-width: 400px) {
  body {
    padding: 0;
  }

  header {
    margin-top: 40px;
  }

  h1 {
    font-size: 2rem;
  }

  #registerSection>h2,
  #loginSection>h2 {
    font-size: 2.2rem;
  }

  #regName,
  #regEmail,
  #regPassword,
  #loginEmail,
  #loginPassword,
  textarea {
    height: 52px;
    font-size: 1rem;
  }

  .tab {
    padding: 12px 24px;
    font-size: 0.95rem;
  }

  button.heart {
    width: 48px;
    height: 48px;
  }

  button.heart::before {
    font-size: 1.5rem;
  }
}