/* ============= 共通樣式 ============= */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
    background: linear-gradient(-45deg, #667eea, #764ba2, #f093fb, #4facfe);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
    position: relative;
    overflow-x: hidden;
}

/* Particles.js 背景容器 */
#particles-js {
    position: fixed;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    z-index: 0;
    background: linear-gradient(-45deg, #667eea, #764ba2, #f093fb, #4facfe);
    background-size: 400% 400%;
    animation: gradientShift 15s ease infinite;
}

@keyframes gradientShift {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

/* 自定義 body 滾動條 */
body::-webkit-scrollbar {
    width: 12px;
}

body::-webkit-scrollbar-track {
    background: rgba(0, 0, 0, 0.1);
}

body::-webkit-scrollbar-thumb {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 6px;
}

body::-webkit-scrollbar-thumb:hover {
    background: linear-gradient(135deg, #764ba2 0%, #667eea 100%);
}

.container {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-radius: 24px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    padding: 48px;
    max-width: 900px;
    width: 100%;
    position: relative;
    z-index: 10;
    border: 1px solid rgba(255, 255, 255, 0.18);
    animation: slideUp 0.6s ease-out;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.header {
    text-align: center;
    margin-bottom: 40px;
}

.header h1 {
    color: #333;
    font-size: 32px;
    font-weight: 700;
    margin-bottom: 8px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.header p {
    color: #666;
    font-size: 15px;
    font-weight: 400;
}

/* Flash 訊息提示 */
.flash-toast {
    position: fixed;
    top: 24px;
    right: 24px;
    color: white;
    padding: 16px 24px;
    border-radius: 12px;
    z-index: 9999;
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 15px;
    font-weight: 600;
    animation: slideInRight 0.3s ease-out;
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.flash-toast.hiding {
    opacity: 0;
    transform: translateX(400px);
}

.flash-toast i {
    font-size: 20px;
}

/* Flash 訊息類型 */
.flash-error {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    box-shadow: 0 8px 24px rgba(245, 87, 108, 0.4);
}

.flash-success {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    box-shadow: 0 8px 24px rgba(79, 172, 254, 0.4);
}

.flash-warning {
    background: linear-gradient(135deg, #ffecd2 0%, #fcb69f 100%);
    box-shadow: 0 8px 24px rgba(252, 182, 159, 0.4);
    color: #333;
}

.flash-info {
    background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
    box-shadow: 0 8px 24px rgba(168, 237, 234, 0.4);
    color: #333;
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(400px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* ============= 登入頁面專屬樣式 ============= */
.logo {
    width: 80px;
    height: 80px;
    margin: 0 auto 20px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 36px;
    box-shadow: 0 8px 24px rgba(102, 126, 234, 0.3);
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

.login-container {
    text-align: center;
    padding: 20px 0;
}

.login-btn {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    padding: 18px 48px;
    font-size: 16px;
    font-weight: 600;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
    position: relative;
    overflow: hidden;
    text-decoration: none;
    display: inline-block;
}

.login-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.2);
    transition: left 0.5s ease;
}

.login-btn:hover::before {
    left: 100%;
}

.login-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.5);
}

.login-btn:active {
    transform: translateY(0);
}

.login-btn i {
    margin-right: 10px;
}

/* 響應式設計 */
@media (max-width: 768px) {
    .container {
        padding: 32px 24px;
    }

    .header h1 {
        font-size: 26px;
    }

    .flash-toast {
        top: 16px;
        right: 16px;
        left: 16px;
        padding: 14px 20px;
        font-size: 14px;
    }
}