/* 基础样式与响应式设计 */
:root {
    --bg-color: #ffffff;
    --text-color: #333333;
    --form-bg: #f5f5f5;
    --border-color: #dddddd;
    --button-bg: #007bff;
    --button-text: #ffffff;
    --error-color: #dc3545;
    --input-focus: #80bdff;
}

/* 深色模式支持 */
@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #1a1a1a;
        --text-color: #e0e0e0;
        --form-bg: #2d2d2d;
        --border-color: #444444;
        --button-bg: #0062cc;
        --button-text: #ffffff;
        --error-color: #ff6b6b;
        --input-focus: #4dabf5;
    }
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.form-container {
    background-color: var(--form-bg);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    width: 100%;
    max-width: 500px;
}

h1 {
    text-align: center;
    margin-bottom: 1.5rem;
    color: var(--text-color);
}

.form-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

input, textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-color: var(--bg-color);
    color: var(--text-color);
    font-size: 1rem;
}

input:focus, textarea:focus {
    outline: none;
    border-color: var(--input-focus);
    box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25);
}

textarea {
    resize: vertical;
}

.error-message {
    color: var(--error-color);
    font-size: 0.875rem;
    margin-top: 0.25rem;
    display: block;
    height: 1.2rem;
}

.form-actions {
    text-align: center;
}

button {
    background-color: var(--button-bg);
    color: var(--button-text);
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
    transition: background-color 0.3s;
}

button:hover {
    opacity: 0.9;
}

button:disabled {
    background-color: #6c757d;
    cursor: not-allowed;
}

/* 响应式调整 */
@media (max-width: 768px) {
    .form-container {
        padding: 1.5rem;
        margin: 0 1rem;
    }
    
    h1 {
        font-size: 1.5rem;
    }
}

.error-message {
    color: red;
    font-weight: bold;
    font-size: 0.875rem;
    margin-top: 0.25rem;
    display: block;
}

/* 弹窗模式样式 */
.popup-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.popup-container {
    width: 90%;
    max-width: 500px;
    background-color: var(--form-bg);
    border-radius: 8px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.2);
    position: relative;
    animation: popupFadeIn 0.3s;
}

@keyframes popupFadeIn {
    from { opacity: 0; transform: translateY(-20px); }
    to { opacity: 1; transform: translateY(0); }
}

.close-btn {
    position: absolute;
    top: 10px;
    right: 10px;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-color);
    padding: 0.25rem;
}