:root { --bg: #f6f7f9; --panel: #fff; --text: #1d2330; --muted: #6b7280; --line: #e5e7eb; --accent: #2c4bff; --err: #b42318; }
@media (prefers-color-scheme: dark) { :root { --bg: #111318; --panel: #1a1d24; --text: #e8eaf0; --muted: #9aa1ad; --line: #2a2f3a; --accent: #6b83ff; } }
body { margin: 0; min-height: 100vh; display: grid; place-items: center; background: var(--bg); color: var(--text); font-family: system-ui, -apple-system, "Hiragino Sans", "Noto Sans JP", sans-serif; padding: 16px; box-sizing: border-box; }
.card { background: var(--panel); border: 1px solid var(--line); border-radius: 14px; padding: 32px; width: 100%; max-width: 360px; text-align: center; }
h1 { font-size: 20px; margin: 0 0 8px; }
p { color: var(--muted); }
.err { color: var(--err); }
.btn { display: inline-block; margin-top: 12px; background: var(--accent); color: #fff; text-decoration: none; padding: 10px 18px; border-radius: 10px; font-weight: 600; }
button.btn { border: 0; font: inherit; cursor: pointer; }
button.btn:disabled { opacity: .6; cursor: default; }
.msg { min-height: 1.4em; font-size: 14px; }
.field { display: block; text-align: left; font-size: 13px; color: var(--muted); margin: 16px 0 4px; }
.field input { display: block; width: 100%; box-sizing: border-box; margin-top: 4px; padding: 8px 10px; border: 1px solid var(--line); border-radius: 8px; background: var(--bg); color: var(--text); font: inherit; }