:root {
    /* Brand Colors - Màu thương hiệu */
    --primary-blue: #2176ff;
    --primary-blue-dark: #1a5bcc;
    --primary-purple: #6C63FF;
    --primary-pink: #FF6584;
    --brand-magenta: #ff0080;

    /* Text Colors - Màu chữ */
    --text-main: #ffffff;
    --text-sub: #E0E0E0;
    --text-muted: #A0A0A0;
    --text-main-grey: #333333;
    --text-sub-grey: #666666;
    
    /* Apple/Premium Monochrome Style */
    --apple-black: #1d1d1f;
    --apple-grey: #86868b;
    --apple-bg: #f5f5f7;

    /* Semantic Colors - Màu chức năng */
    --success: #12b76a;
    --warning: #f79009;
    --error: #ff4d4d;
    --price-color: #FF6584;

    /* Backgrounds & Borders */
    --background-color: #f5f5f7;
    --card-bg: #ffffff;
    --border-color: #e1e1e1;
    --border-focus: #6C63FF;

    /* Glassmorphism & Transparencies */
    --glass-bg: rgba(20, 20, 20, 0.7);
    --glass-border: rgba(255, 255, 255, 0.1);
    --white-05: rgba(255, 255, 255, 0.05);
    --white-10: rgba(255, 255, 255, 0.1);
    --white-20: rgba(255, 255, 255, 0.2);
    --purple-05: rgba(108, 99, 255, 0.05);
    --purple-30: rgba(108, 99, 255, 0.3);

    /* UI Components */
    --button-bg: #94B4C1;
    --navbar-height: 80px;
    --footer-height: 70px;
}

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

html {
    font-size: 62.5%;
    line-height: 1.6rem;
    font-family: 'Be Vietnam Pro', sans-serif;
    box-sizing: border-box;
    scroll-behavior: smooth;
}

body {
    font-family: 'Be Vietnam Pro', sans-serif;
    font-size: 1.6rem;
    line-height: 1.6rem;

    display: flex;
    flex-direction: column;

    min-height: 100vh;

    overflow-y: auto;
    overflow-x: hidden;
}

html, body {
    height: 100%;
    padding: 0;
    margin: 0;
    overflow-x: hidden; 
}

/* Button */
.button {
    padding: 16px 32px;
    margin-top: 18px;

    color: var(--text-main);
    
    border: none;

    font-size: 1.4rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;

    border-radius: 50px;
    cursor: pointer;

    transition: all 0.3s ease;
}

.button:hover {
    transform: translateY(-3px);
    
    box-shadow: 0 8px 25px rgba(108, 99, 255, 0.6);
    
    filter: brightness(1.1); 
}

/* Auth Form - Premium Monochrome Redesign */
.auth-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;

    background: rgba(255, 255, 255, 0.4);
    backdrop-filter: blur(15px) saturate(180%);
    -webkit-backdrop-filter: blur(15px) saturate(180%);

    display: none;
    justify-content: center;
    align-items: center;
    z-index: 9999;
}

.auth-card {
    position: relative;
    background: #ffffff;
    border: 1px solid rgba(0, 0, 0, 0.08);
    padding: 40px 35px;
    border-radius: 24px;

    width: 90%;
    max-width: 420px;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.15);
    
    animation: authModalFadeIn 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

@keyframes authModalFadeIn {
    from { opacity: 0; transform: scale(0.95) translateY(10px); }
    to { opacity: 1; transform: scale(1) translateY(0); }
}

.auth-card__close {
    position: absolute;
    top: 25px;
    right: 25px;
    font-size: 2.22rem;
    color: var(--apple-grey);
    cursor: pointer;
    transition: all 0.2s ease;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    background: #f5f5f7;
}

.auth-card__close:hover {
    color: var(--apple-black);
    background: #e8e8ed;
    transform: rotate(90deg);
}

.auth-card__title {
    font-size: 2.8rem;
    color: var(--apple-black);
    text-align: center;
    margin-bottom: 35px;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.auth-card__form {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.auth-card__group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.auth-card__heading {
    color: var(--apple-grey);
    font-size: 1.3rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-left: 4px;
}

.auth-card__input {
    width: 100%;
    background: #f5f5f7;
    border: 1px solid transparent;
    border-radius: 12px;
    color: var(--apple-black);
    font-size: 1.6rem;
    padding: 14px 18px;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.auth-card__input:focus {
    outline: none;
    background: #ffffff;
    border-color: var(--primary-blue);
    box-shadow: 0 0 0 4px rgba(33, 118, 255, 0.1);
}

.auth-card__button {
    width: 100%;
    margin-top: 15px;
    background-color: var(--apple-black);
    color: #fff;
    border-radius: 14px;
    padding: 16px;
    font-size: 1.6rem;
    font-weight: 600;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.auth-card__button:hover {
    background-color: #333;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.15);
}

/* Trạng thái Loading cho nút */
.btn-loading {
    position: relative;
    color: transparent !important;
    pointer-events: none;
    opacity: 0.8;
}

.btn-loading::after {
    content: "";
    position: absolute;
    width: 20px;
    height: 20px;
    top: calc(50% - 10px);
    left: calc(50% - 10px);
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 0.8s ease-in-out infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.auth-card__switch {
    margin-top: 25px;
    color: var(--apple-grey);
    text-align: center;
    font-size: 1.5rem;
}

.auth-card__switch a {
    color: var(--primary-blue);
    text-decoration: none;
    font-weight: 600;
    margin-left: 5px;
    transition: all 0.2s ease;
}

.auth-card__switch a:hover {
    text-decoration: underline;
    opacity: 0.8;
}