:root {
    --primary: #2563eb;
    --dark: #1e293b;
    --border: #e2e8f0;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
    font-family: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', Meiryo, sans-serif;
    background: #f8fafc;
    color: #334155;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

.login-card {
    background: white;
    border: 1px solid var(--border);
    border-radius: 12px;
    box-shadow: 0 2px 16px rgba(0,0,0,0.08);
    padding: 40px 36px;
    width: 320px;
    text-align: center;
}

.login-title {
    font-size: 20px;
    font-weight: bold;
    color: var(--dark);
    margin-bottom: 8px;
}

.login-sub {
    font-size: 13px;
    color: #64748b;
    margin-bottom: 28px;
    line-height: 1.6;
}

.login-error {
    display: none;
    background: #fef2f2;
    border-left: 4px solid #dc2626;
    color: #991b1b;
    font-size: 12px;
    padding: 10px 12px;
    border-radius: 0 6px 6px 0;
    margin-bottom: 16px;
    text-align: left;
    line-height: 1.6;
}

.login-error.visible { display: block; }

.google-btn {
    width: 100%;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 12px 18px;
    background: white;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 14px;
    font-weight: bold;
    color: var(--dark);
    cursor: pointer;
    font-family: inherit;
    transition: box-shadow 0.2s, transform 0.1s;
}

.google-btn:hover { box-shadow: 0 2px 8px rgba(0,0,0,0.1); }
.google-btn:active { transform: scale(0.98); }