:root { --bg: #f4f6fa; --surface: #fff; --text: #0f172a; --muted: #64748b; --border: #d6dde8; --accent: #2563eb; --danger: #b91c1c;
  font-family: Inter, "Segoe UI", system-ui, -apple-system, sans-serif; color-scheme: light; }
@media (prefers-color-scheme: dark) {
  :root { --bg: #0b0f17; --surface: #151b26; --text: #e2e8f0; --muted: #94a3b8; --border: #2b3547; --accent: #60a5fa; --danger: #f87171; color-scheme: dark; }
}
* { box-sizing: border-box; }
body { margin: 0; min-height: 100vh; display: grid; place-items: center; background: var(--bg); color: var(--text); padding: 16px; }
.card { width: min(380px, 100%); background: var(--surface); border: 1px solid var(--border); border-radius: 14px; padding: 28px 28px 20px; box-shadow: 0 10px 30px rgba(15, 23, 42, .08); }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 17px; }
h1 { font-size: 22px; margin: 18px 0 16px; }
form { display: flex; flex-direction: column; gap: 14px; }
label { display: flex; flex-direction: column; gap: 6px; font-size: 13px; font-weight: 600; color: var(--muted); }
input { font: inherit; font-size: 15px; font-weight: 400; color: var(--text); background: var(--surface); padding: 10px 12px; border: 1px solid var(--border); border-radius: 9px; }
input:focus-visible, button:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
button { font: inherit; font-weight: 600; padding: 11px; border-radius: 9px; border: 1px solid var(--accent); background: var(--accent); color: #fff; cursor: pointer; margin-top: 4px; }
button:disabled { opacity: .6; cursor: default; }
.error { margin: 0; color: var(--danger); font-size: 14px; }
.hint { color: var(--muted); font-size: 13px; margin: 18px 0 0; }
/* v3.1: Microsoft sign-in */
.sso[hidden] { display: none; }
.sso .or { display: flex; align-items: center; gap: 10px; color: var(--muted); font-size: 13px; margin: 16px 0 12px; }
.sso .or::before, .sso .or::after { content: ""; flex: 1; border-top: 1px solid var(--border); }
.sso-btn { display: flex; align-items: center; justify-content: center; gap: 10px; padding: 10px; border: 1px solid var(--border); border-radius: 9px; color: var(--text); text-decoration: none; font-weight: 600; background: var(--surface); }
.sso-btn:hover { border-color: var(--accent); }
.sso-btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
.ms-logo { display: grid; grid-template-columns: 8px 8px; gap: 2px; }
.ms-logo i { width: 8px; height: 8px; display: block; }
.ms-logo i:nth-child(1) { background: #f25022; } .ms-logo i:nth-child(2) { background: #7fba00; }
.ms-logo i:nth-child(3) { background: #00a4ef; } .ms-logo i:nth-child(4) { background: #ffb900; }

/* v3.5: Windows sign-in button (and each button can be hidden on its own) */
.sso-btn[hidden] { display: none; }
.sso-btn + .sso-btn { margin-top: 8px; }
.win-logo { display: grid; grid-template-columns: 8px 8px; gap: 2px; transform: perspective(40px) rotateY(-12deg); }
.win-logo i { width: 8px; height: 8px; background: #0078d4; display: block; }