/* ========== 登录页面样式 ========== */

:root {
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #475569;
    --text-tertiary: #94a3b8;
    --border-color: #e2e8f0;
    --input-bg: #ffffff;
    --input-border: #cbd5e1;
    --accent-color: #4f46e5;
    --accent-hover: #4338ca;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --error-color: #ef4444;
    --success-color: #10b981;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --bg-gradient-start: #e0e7ff;
    --bg-gradient-end: #818cf8;
}

[data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-tertiary: #94a3b8;
    --border-color: #334155;
    --input-bg: #1e293b;
    --input-border: #475569;
    --accent-color: #6366f1;
    --accent-hover: #818cf8;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.5);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.7);
    --bg-gradient-start: #0f172a;
    --bg-gradient-end: #1e293b;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg-primary);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    color: var(--text-primary);
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container { width: 100%; max-width: 420px; position: relative; }

.theme-toggle-btn {
    position: absolute; top: -60px; right: 0;
    width: 40px; height: 40px; border-radius: 50%;
    border: 1px solid var(--border-color);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 18px; cursor: pointer;
    display: flex; align-items: center; justify-content: center;
    transition: all 0.2s ease; box-shadow: var(--shadow-sm);
}
.theme-toggle-btn:hover { border-color: var(--accent-color); color: var(--accent-color); transform: translateY(-2px); box-shadow: var(--shadow-md); }

.back-link {
    position: absolute; top: -60px; left: 0;
    padding: 8px 16px; background: var(--bg-secondary);
    color: var(--text-secondary); border: 1px solid var(--border-color);
    border-radius: var(--radius-md); font-size: 14px; font-weight: 500;
    cursor: pointer; transition: all 0.2s; text-decoration: none;
    display: flex; align-items: center; gap: 6px; box-shadow: var(--shadow-sm);
}
.back-link:hover { border-color: var(--accent-color); color: var(--accent-color); transform: translateY(-2px); box-shadow: var(--shadow-md); }

.login-card {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    padding: 40px;
    border: 1px solid var(--border-color);
}

.header { text-align: center; margin-bottom: 32px; }
.header h1 { font-size: 24px; margin-bottom: 8px; font-weight: 700; color: var(--text-primary); }
.subtitle { font-size: 14px; color: var(--text-secondary); }

.input-group { margin-bottom: 24px; }
.input-group label { display: block; font-size: 14px; font-weight: 500; margin-bottom: 8px; color: var(--text-primary); }

.login-input {
    width: 100%; height: 48px; padding: 0 16px; font-size: 16px;
    border: 1px solid var(--input-border); border-radius: var(--radius-md);
    background: var(--input-bg); color: var(--text-primary);
    transition: all 0.2s; outline: none;
}
.login-input:focus { border-color: var(--accent-color); box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1); }

.login-btn {
    width: 100%; height: 50px; background: var(--accent-color);
    color: #fff; border: none; border-radius: var(--radius-md);
    font-size: 16px; font-weight: 600; cursor: pointer; transition: all 0.2s;
}
.login-btn:hover { background: var(--accent-hover); transform: translateY(-1px); box-shadow: var(--shadow-md); }
.login-btn:disabled { background: var(--text-tertiary); cursor: not-allowed; }

.alert-box {
    padding: 12px; border-radius: var(--radius-md); margin-bottom: 20px;
    display: none; font-size: 14px; border: 1px solid transparent;
}
.alert-box.error { background: rgba(239, 68, 68, 0.1); border-color: rgba(239, 68, 68, 0.2); color: var(--error-color); }

.page-loader {
    position: fixed; top: 0; left: 0; width: 100%; height: 100%;
    background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
    display: flex; flex-direction: column; align-items: center; justify-content: center;
    z-index: 9999; transition: opacity 0.5s ease, visibility 0.5s ease;
}
.page-loader.hidden { opacity: 0; visibility: hidden; }
.loader-spinner {
    width: 50px; height: 50px;
    border: 4px solid rgba(255,255,255,0.3);
    border-top-color: #fff; border-radius: 50%;
    animation: spin 1s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

@media (max-width: 480px) {
    .login-card { padding: 24px; }
    .container { padding: 0 16px; }
}