:root {
    --bg: #090909;
    --panel: #111111;
    --border: #2b2b2b;
    --text: #f2f2f2;
    --muted: #a3a3a3;
    --field: #151515;
    --accent: #f1f1f1;
    --accent-text: #101010;
    --danger: #ed5b5b;
    --danger-bg: rgba(237, 91, 91, .14);
    --danger-border: rgba(237, 91, 91, .42);
}
[data-theme="light"] {
    --bg: #f5f5f5;
    --panel: #ffffff;
    --border: #dddddd;
    --text: #131313;
    --muted: #686868;
    --field: #fafafa;
    --accent: #181818;
    --accent-text: #ffffff;
    --danger: #c23939;
    --danger-bg: #fbeaea;
    --danger-border: #e6adad;
}
* { box-sizing: border-box; }
body {
    margin: 0; min-height: 100vh; padding: 16px; display: grid; place-items: center;
    font-family: Inter, "Segoe UI", Arial, sans-serif; color: var(--text);
    background: var(--bg);
}
.login-box {
    width: min(390px, 100%); padding: 34px 30px 30px; border-radius: 18px;
    background: var(--panel); border: 1px solid var(--border);
    box-shadow: 0 24px 70px rgba(0,0,0,.34);
}
.brand-mark {
    width: 44px; height: 44px; margin: 0 auto 18px; display: grid; place-items: center;
    background: var(--accent); border-radius: 13px;
    color: var(--accent-text); font-size: 22px; font-weight: 900;
}
h2 { text-align: center; margin: 0 0 7px; font-size: 25px; letter-spacing: -.04em; }
p { text-align: center; color: var(--muted); font-size: 14px; margin: 0 0 24px; }
input {
    width: 100%; padding: 12px 15px; margin: 7px 0; border-radius: 10px;
    border: 1px solid var(--border); background: var(--field); color: var(--text); font-size: 15px;
}
input:focus { outline: 2px solid var(--text); border-color: var(--text); }
button {
    width: 100%; padding: 12px 15px; border: 0; margin-top: 14px; border-radius: 10px;
    color: var(--accent-text); background: var(--accent); font-size: 15px; font-weight: 700; cursor: pointer;
}
button:hover { filter: brightness(1.08); }
.error {
    margin: 18px 0; padding: 11px; border-radius: 10px; text-align: center; font-size: 14px;
    color: var(--danger); background: var(--danger-bg); border: 1px solid var(--danger-border);
}
.theme-toggle {
    position: fixed; top: 20px; right: 20px; width: 42px; height: 42px; margin: 0;
    padding: 0; display: grid; place-items: center; color: var(--text);
    background: var(--panel); border: 1px solid var(--border);
}
.theme-icon { width: 19px; height: 19px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.theme-icon-moon { display: none; }
[data-theme="light"] .theme-icon-sun { display: none; }
[data-theme="light"] .theme-icon-moon { display: block; }