:root {
  --ks-yellow: #FFC800;
  --ks-yellow-dim: #C99A00;
  --ks-black: #0E0E0F;
  --ks-black-soft: #1A1A1C;
  --ks-black-card: #222224;
  --ks-border: #2E2E31;
  --ks-text: #F2F2F0;
  --ks-text-dim: #A6A6A9;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: 'Segoe UI', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--ks-black);
  color: var(--ks-text);
}

/* ---------- AUTH PAGES ---------- */
.auth-body {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  background: radial-gradient(circle at top, #1c1c1e 0%, var(--ks-black) 70%);
}

.auth-card {
  background: var(--ks-black-card);
  border: 1px solid var(--ks-border);
  border-radius: 16px;
  padding: 40px;
  width: 100%;
  max-width: 380px;
  text-align: center;
  box-shadow: 0 0 40px rgba(255, 200, 0, 0.05);
}

.auth-logo {
  width: 56px;
  height: 56px;
  margin: 0 auto 16px;
  background: var(--ks-yellow);
  color: var(--ks-black);
  font-weight: 800;
  font-size: 22px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.auth-card h1 { font-size: 22px; margin: 0 0 4px; }
.auth-sub { color: var(--ks-text-dim); font-size: 14px; margin-bottom: 24px; }

.auth-form { display: flex; flex-direction: column; gap: 12px; }

.auth-form input {
  background: var(--ks-black-soft);
  border: 1px solid var(--ks-border);
  color: var(--ks-text);
  padding: 12px 14px;
  border-radius: 10px;
  font-size: 14px;
  outline: none;
}
.auth-form input:focus { border-color: var(--ks-yellow); }

.btn-primary {
  background: var(--ks-yellow);
  color: var(--ks-black);
  border: none;
  padding: 12px;
  border-radius: 10px;
  font-weight: 700;
  cursor: pointer;
  font-size: 14px;
  margin-top: 4px;
}
.btn-primary:hover { background: var(--ks-yellow-dim); }

.btn-guest {
  display: block;
  margin-top: 14px;
  color: var(--ks-text-dim);
  text-decoration: none;
  font-size: 13px;
  border: 1px solid var(--ks-border);
  padding: 10px;
  border-radius: 10px;
}
.btn-guest:hover { border-color: var(--ks-yellow-dim); color: var(--ks-text); }

.auth-error {
  background: rgba(255, 80, 80, 0.1);
  color: #ff8080;
  padding: 8px 12px;
  border-radius: 8px;
  font-size: 13px;
  margin-bottom: 16px;
}

.auth-switch { margin-top: 20px; font-size: 13px; color: var(--ks-text-dim); }
.auth-switch a { color: var(--ks-yellow); text-decoration: none; }

/* ---------- CHAT APP ---------- */
.chat-body { margin: 0; height: 100vh; overflow: hidden; }

.app-shell { display: flex; height: 100vh; }

.sidebar {
  width: 270px;
  background: var(--ks-black-soft);
  border-right: 1px solid var(--ks-border);
  display: flex;
  flex-direction: column;
  transition: margin-left 0.2s ease;
}

.sidebar-top { padding: 16px; border-bottom: 1px solid var(--ks-border); }

.brand { display: flex; align-items: center; gap: 8px; margin-bottom: 14px; font-weight: 700; }
.brand-ks {
  background: var(--ks-yellow);
  color: var(--ks-black);
  padding: 4px 8px;
  border-radius: 6px;
  font-size: 13px;
}
.brand-name { font-size: 15px; }

.btn-new-chat {
  width: 100%;
  background: transparent;
  border: 1px solid var(--ks-yellow-dim);
  color: var(--ks-yellow);
  padding: 10px;
  border-radius: 10px;
  cursor: pointer;
  font-weight: 600;
  font-size: 13px;
}
.btn-new-chat:hover { background: rgba(255, 200, 0, 0.08); }

.sessions-list { flex: 1; overflow-y: auto; padding: 8px; }

.session-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 12px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 13px;
  color: var(--ks-text-dim);
  margin-bottom: 2px;
}
.session-item:hover, .session-item.active {
  background: var(--ks-black-card);
  color: var(--ks-text);
}
.session-title { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; flex: 1; }
.session-delete {
  background: none; border: none; color: var(--ks-text-dim);
  cursor: pointer; font-size: 16px; padding: 0 4px; display: none;
}
.session-item:hover .session-delete { display: block; }
.session-delete:hover { color: #ff8080; }

.sidebar-bottom {
  padding: 14px 16px;
  border-top: 1px solid var(--ks-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 13px;
}
.guest-tag {
  background: var(--ks-yellow-dim);
  color: var(--ks-black);
  font-size: 10px;
  padding: 2px 6px;
  border-radius: 6px;
  margin-left: 6px;
  vertical-align: middle;
}
.btn-logout { color: var(--ks-text-dim); text-decoration: none; }
.btn-logout:hover { color: var(--ks-yellow); }

.chat-main { flex: 1; display: flex; flex-direction: column; min-width: 0; }

.chat-topbar {
  padding: 14px 20px;
  border-bottom: 1px solid var(--ks-border);
  display: flex;
  align-items: center;
  gap: 12px;
}
.sidebar-toggle {
  background: none; border: none; color: var(--ks-text); font-size: 18px; cursor: pointer; display: none;
}
.chat-title { font-weight: 600; color: var(--ks-text-dim); }

.chat-window {
  flex: 1;
  overflow-y: auto;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.welcome-screen {
  margin: auto;
  text-align: center;
  color: var(--ks-text-dim);
  max-width: 420px;
}
.welcome-logo {
  width: 64px; height: 64px;
  background: var(--ks-yellow);
  color: var(--ks-black);
  font-weight: 800;
  font-size: 26px;
  border-radius: 16px;
  display: flex; align-items: center; justify-content: center;
  margin: 0 auto 16px;
}
.welcome-screen h2 { color: var(--ks-text); margin-bottom: 8px; }

.msg { max-width: 72%; padding: 12px 16px; border-radius: 14px; line-height: 1.5; font-size: 14.5px; white-space: pre-wrap; }
.msg.user { align-self: flex-end; background: var(--ks-yellow); color: var(--ks-black); border-bottom-right-radius: 4px; }
.msg.assistant { align-self: flex-start; background: var(--ks-black-card); border: 1px solid var(--ks-border); border-bottom-left-radius: 4px; }
.msg.typing { align-self: flex-start; color: var(--ks-text-dim); font-style: italic; }

.chat-input-bar {
  display: flex;
  align-items: flex-end;
  gap: 8px;
  padding: 14px 20px;
  border-top: 1px solid var(--ks-border);
  background: var(--ks-black-soft);
}
.chat-input-bar textarea {
  flex: 1;
  background: var(--ks-black-card);
  border: 1px solid var(--ks-border);
  color: var(--ks-text);
  border-radius: 12px;
  padding: 12px 14px;
  font-size: 14px;
  resize: none;
  max-height: 140px;
  font-family: inherit;
  outline: none;
}
.chat-input-bar textarea:focus { border-color: var(--ks-yellow-dim); }

.icon-btn {
  background: var(--ks-black-card);
  border: 1px solid var(--ks-border);
  color: var(--ks-text-dim);
  width: 42px; height: 42px;
  border-radius: 10px;
  cursor: pointer;
  font-size: 16px;
  flex-shrink: 0;
}
.icon-btn:hover { border-color: var(--ks-yellow-dim); color: var(--ks-yellow); }
.send-btn { background: var(--ks-yellow); color: var(--ks-black); border: none; }
.send-btn:hover { background: var(--ks-yellow-dim); }

.motivation-toast {
  position: fixed;
  top: 16px;
  right: 16px;
  background: var(--ks-black-card);
  border: 1px solid var(--ks-yellow-dim);
  color: var(--ks-text);
  padding: 14px 18px;
  border-radius: 12px;
  max-width: 320px;
  font-size: 13.5px;
  display: flex;
  align-items: flex-start;
  gap: 10px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.4);
  z-index: 999;
}
.motivation-toast button {
  background: none; border: none; color: var(--ks-text-dim); cursor: pointer; font-size: 16px;
}

.site-footer {
  text-align: center;
  font-size: 11px;
  color: var(--ks-text-dim);
  padding: 6px;
  background: var(--ks-black-soft);
  border-top: 1px solid var(--ks-border);
}

/* ---------- MOBILE ---------- */
@media (max-width: 768px) {
  .sidebar { position: fixed; left: 0; top: 0; bottom: 0; z-index: 100; margin-left: -270px; }
  .sidebar.open { margin-left: 0; }
  .sidebar-toggle { display: block; }
  .msg { max-width: 88%; }
}