* { box-sizing: border-box; }

body {
    margin: 0;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: -apple-system, "Segoe UI", "Microsoft YaHei", Roboto, Helvetica, Arial, sans-serif;
    background: linear-gradient(135deg, #1e3a8a 0%, #2563eb 45%, #6366f1 100%);
}

.login-wrap { width: 100%; max-width: 400px; padding: 20px; }

.login-card {
    background: #fff;
    border-radius: 16px;
    padding: 34px 32px 26px;
    box-shadow: 0 24px 60px rgba(2, 6, 23, .35);
}

.login-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 20px;
    font-weight: 700;
    color: #1e293b;
}
.login-brand .logo {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px; height: 36px;
    border-radius: 10px;
    background: linear-gradient(135deg, #3b82f6, #6366f1);
    color: #fff;
    font-size: 17px;
}
.sub { color: #64748b; font-size: 13.5px; margin: 8px 0 22px; }

.field { margin-bottom: 16px; }
.field label { display: block; font-size: 13px; color: #475569; margin-bottom: 6px; }
.field input {
    width: 100%;
    padding: 11px 14px;
    border: 1px solid #dbe2ea;
    border-radius: 9px;
    font-size: 14.5px;
    outline: none;
    transition: border-color .15s, box-shadow .15s;
}
.field input:focus {
    border-color: #2563eb;
    box-shadow: 0 0 0 3px rgba(37, 99, 235, .14);
}

.err { color: #ef4444; font-size: 13px; min-height: 18px; margin-bottom: 6px; }

#btn {
    width: 100%;
    padding: 12px;
    border: none;
    border-radius: 9px;
    background: linear-gradient(135deg, #2563eb, #4f46e5);
    color: #fff;
    font-size: 15px;
    font-weight: 600;
    letter-spacing: 2px;
    cursor: pointer;
    transition: opacity .15s, transform .05s;
}
#btn:hover { opacity: .94; }
#btn:active { transform: translateY(1px); }
#btn:disabled { opacity: .6; cursor: not-allowed; }

.tip { margin-top: 18px; font-size: 12.5px; color: #94a3b8; text-align: center; }
.tip b { color: #64748b; }