body {
  font-family: "Yu Gothic", "メイリオ", sans-serif;
  background: #f6fafc;
  margin: 0;
  color: #222;
}
header {
  background: #73a7e6;
  color: #fff;
  padding: 10px 0;
  text-align: center;
}
header h1 {
  margin: 0;
  font-size: 1.7em;
  letter-spacing: 0.06em;
}
nav {
  margin: 10px 0 0;
}
nav button {
  background: #fff;
  color: #73a7e6;
  border: none;
  margin: 0 4px;
  padding: 6px 16px;
  border-radius: 18px;
  font-size: 0.95em;
  cursor: pointer;
  transition: background 0.2s;
}
nav button:hover {
  background: #e3f0fa;
}
main {
  max-width: 600px;
  margin: 20px auto 50px;
  background: #fff;
  border-radius: 10px;
  box-shadow: 0 1px 5px #ccc;
  padding: 20px;
}
#authTabs {
  text-align: center;
  margin-bottom: 10px;
}
#authTabs button {
  border: none;
  background: #e3f0fa;
  color: #3570b7;
  padding: 8px 26px;
  margin: 0 6px;
  font-size: 1em;
  border-radius: 16px 16px 0 0;
  cursor: pointer;
}
#authTabs .active {
  background: #73a7e6;
  color: #fff;
}
form label {
  display: block;
  margin: 10px 0 6px;
}
form input, form textarea, form select {
  width: 100%;
  padding: 8px;
  box-sizing: border-box;
  margin-top: 3px;
  border-radius: 5px;
  border: 1px solid #b3d0ef;
  font-size: 1em;
}
form button {
  background: #73a7e6;
  color: #fff;
  border: none;
  padding: 8px 22px;
  margin-top: 14px;
  font-size: 1em;
  border-radius: 18px;
  cursor: pointer;
  transition: background 0.2s;
}
form button:hover {
  background: #3570b7;
}
#oauthBtns button {
  width: 48%;
  margin: 6px 1%;
  background: #fff;
  border: 1px solid #73a7e6;
  color: #3570b7;
  border-radius: 18px;
  padding: 8px 0;
}
#oauthBtns button:hover {
  background: #e3f0fa;
}
#profileMsg, #globalMsg {
  margin: 12px 0 0;
  color: #3570b7;
  font-size: 0.98em;
}
#userList, #adminUserList, #adminChatList {
  list-style: none;
  padding: 0;
}
#userList li, #adminUserList li, #adminChatList li {
  margin: 7px 0;
  background: #f4faff;
  padding: 8px 10px;
  border-radius: 7px;
  box-shadow: 0 1px 2px #cfe4fa33;
}
#chatUsersWrap {
  margin-bottom: 10px;
}
#chatHistory {
  height: 230px;
  overflow-y: auto;
  background: #f4faff;
  border-radius: 8px;
  padding: 10px;
  margin-bottom: 7px;
  border: 1px solid #e3f0fa;
  font-size: 0.98em;
}
.message-row {
  margin-bottom: 8px;
}
.message-row.self {
  text-align: right;
}
.message-row .nickname {
  font-weight: bold;
  font-size: 0.98em;
  color: #73a7e6;
}
.message-row .timestamp {
  font-size: 0.8em;
  color: #888;
  margin-left: 8px;
}
footer {
  text-align: center;
  color: #aaa;
  font-size: 0.92em;
  margin-top: 40px;
  margin-bottom: 12px;
}
@media (max-width: 750px) {
  main {
    max-width: 97vw;
    padding: 14px;
    font-size: 0.98em;
  }
  header h1 {
    font-size: 1.2em;
  }
  #chatHistory {
    height: 32vw;
    min-height: 120px;
    font-size: 0.95em;
  }
}