:root {
    /* SF Pro Display 用于标题和大号文本 */
    --font-family-display: -apple-system, "SF Pro Display", "SF Pro Icons", "Helvetica Neue", Helvetica, Arial, sans-serif;
    /* SF Pro Text 用于正文和小号文本 */
    --font-family-text: -apple-system, "SF Pro Text", "SF Pro Icons", "Helvetica Neue", Helvetica, Arial, sans-serif;
    --color-primary: #0071e3;
    --color-primary-hover: #0077ed;
    --color-primary-active: #006edb;
    --color-error: #ff6b6b;
    --color-text: #fff;
    --color-text-secondary: rgba(255, 255, 255, 0.6);
}

body {
    overflow: hidden;
    margin: 0;
    font-family: var(--font-family-text);
    font-size: 17px;
    line-height: 1.47059;
    font-weight: 400;
    letter-spacing: -0.022em;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    background: #000;
}

#bg-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
    opacity: 0.8;
}

.container {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    position: relative;
    z-index: 2;
    pointer-events: none;
}

.login-box {
    padding: 24px;
    text-align: center;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-radius: 16px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.2);
    width: 280px;
    pointer-events: auto;
    position: relative;
}

.login-box h2 {
    color: var(--color-text);
    margin-bottom: 20px;
    font-family: var(--font-family-display);
    font-size: 24px;
    line-height: 1.16667;
    font-weight: 500;
    letter-spacing: 0.009em;
    text-align: center;
}

.input-group {
    margin: 20px 0;
}

input {
    width: calc(100% - 24px);
    padding: 10px 12px;
    margin-bottom: 14px;
    border: none;
    border-radius: 8px;
    background: rgba(255, 255, 255, 0.1);
    color: var(--color-text);
    outline: none;
    font-family: var(--font-family-text);
    font-size: 17px;
    line-height: 1.23536;
    font-weight: 400;
    letter-spacing: -0.022em;
}

input::placeholder {
    color: var(--color-text-secondary);
}

button {
    width: 100%;
    padding: 12px 20px;
    border: none;
    border-radius: 8px;
    background: var(--color-primary);
    color: var(--color-text);
    cursor: pointer;
    transition: all 0.3s ease;
    font-family: var(--font-family-text);
    font-size: 17px;
    line-height: 1.23536;
    font-weight: 400;
    letter-spacing: -0.022em;
}

button:hover {
    background: var(--color-primary-hover);
}

button:active {
    background: var(--color-primary-active);
    transform: scale(0.98);
}

.error {
    color: var(--color-error);
    display: none;
    font-family: var(--font-family-text);
    font-size: 12px;
    line-height: 1.33337;
    font-weight: 400;
    letter-spacing: -0.01em;
    margin-top: 8px;
}

.language-switch {
    display: flex;
    justify-content: center;
    gap: 12px;
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.lang-btn {
    background: none;
    border: none;
    padding: 6px 12px;
    border-radius: 6px;
    color: var(--color-text-secondary);
    font-family: var(--font-family-text);
    font-size: 12px;
    line-height: 1.33337;
    font-weight: 400;
    letter-spacing: -0.01em;
    cursor: pointer;
    transition: all 0.2s ease;
    min-width: 40px;
}

.lang-btn:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--color-text);
}

.lang-btn.active {
    background: rgba(255, 255, 255, 0.15);
    color: var(--color-text);
}