/* Global Variables - Light Theme */
:root {
    --primary-accent: #007BFF; /* Vibrant Blue */
    --secondary-accent: #28A745; /* Bright Green */
    
    --bg-main: #FFFFFF;
    --bg-alt: #F8FAFC; /* Slightly off-white for sections/cards */
    --bg-subtle-accent: #E7F3FF; /* Very light blue for subtle backgrounds */

    --text-primary: #1E293B; /* Dark Slate Gray for main text */
    --text-secondary: #64748B; /* Lighter Slate Gray for secondary text */
    --text-on-accent: #FFFFFF; /* White text for use on accent backgrounds */

    --border-color: #E2E8F0; /* Light Gray for borders */
    --border-color-strong: #CBD5E1;

    --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.03);
    --shadow-sm: 0 2px 4px -1px rgba(0, 0, 0, 0.06), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 8px -2px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.07);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.07);
    
    --header-height: 70px; 
}

/* Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    background-color: var(--bg-alt);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--header-height);
    display: flex;
    align-items: center;
    background-color: rgba(255, 255, 255, 0.95);
    z-index: 1000;
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
    box-shadow: var(--shadow-md);
    border-bottom: 1px solid var(--border-color);
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.logo {
    display: flex;
    align-items: center;
    text-decoration: none;
}

.logo-text {
    font-size: 1.6rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary-accent), var(--secondary-accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    color: transparent;
    letter-spacing: -0.5px;
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-link:hover {
    color: var(--primary-accent);
}

a.logo:link,
a.logo:visited,
a.logo:hover,
a.logo:active {
    text-decoration: none;
    border-bottom: none;
}

/* Main Content */
main {
    padding-top: var(--header-height);
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    padding-bottom: 2rem;
}

.signin-container {
    width: 100%;
    max-width: 450px;
    margin: 2rem;
    padding: 2.5rem;
    background-color: var(--bg-main);
    border-radius: 16px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
}

.signin-header {
    text-align: center;
    margin-bottom: 2rem;
}

.signin-title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.signin-subtitle {
    color: var(--text-secondary);
    font-size: 1rem;
}

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

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
    font-size: 0.9rem;
}

.form-input {
    width: 100%;
    padding: 0.8rem 1rem;
    border: 1.5px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--bg-main);
    color: var(--text-primary);
    font-size: 1rem;
    transition: border-color 0.3s, box-shadow 0.3s;
}

.form-input:focus {
    outline: none;
    border-color: var(--primary-accent);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.1);
}

.form-input::placeholder {
    color: #A1A5B7;
}

.input-with-icon {
    position: relative;
}

.input-icon {
    position: absolute;
    top: 50%;
    right: 1rem;
    transform: translateY(-50%);
    color: var(--text-secondary);
    cursor: pointer;
    font-size: 1rem;
}

.password-toggle {
    background: none;
    border: none;
    padding: 0;
    cursor: pointer;
    color: var(--text-secondary);
}

.forgot-password {
    text-align: right;
    margin-top: -1rem;
    margin-bottom: 1.5rem;
}

.forgot-password a {
    color: var(--primary-accent);
    font-size: 0.85rem;
    text-decoration: none;
    font-weight: 500;
}

.forgot-password a:hover {
    text-decoration: underline;
}

.remember-me {
    display: flex;
    align-items: center;
    margin-bottom: 1.5rem;
}

.remember-me input[type="checkbox"] {
    margin-right: 0.5rem;
    width: 16px;
    height: 16px;
    accent-color: var(--primary-accent);
}

.remember-me label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    cursor: pointer;
}

.submit-btn {
    width: 100%;
    background: linear-gradient(135deg, var(--primary-accent), #0056b3);
    color: var(--text-on-accent);
    padding: 0.9rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    font-size: 1rem;
    border: none;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
    margin-top: 0.5rem;
}

.submit-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.divider {
    display: flex;
    align-items: center;
    margin: 1.5rem 0;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.divider::before, .divider::after {
    content: '';
    flex: 1;
    height: 1px;
    background-color: var(--border-color);
}

.divider::before {
    margin-right: 1rem;
}

.divider::after {
    margin-left: 1rem;
}

.social-signin {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.social-btn {
    width: 50px;
    height: 50px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--bg-main);
    border: 1.5px solid var(--border-color);
    font-size: 1.5rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.social-btn:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.social-btn.google { color: #EA4335; }
.social-btn.github { color: #333333; }
.social-btn.binance { color: #F3BA2F; }

.signup-link {
    text-align: center;
    margin-top: 1.5rem;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.signup-link a {
    color: var(--primary-accent);
    font-weight: 500;
    text-decoration: none;
}

.signup-link a:hover {
    text-decoration: underline;
}

/* Media queries */
@media (max-width: 768px) {
    .signin-container {
        margin: 1rem;
        padding: 1.5rem;
        max-width: 100%;
    }
    
    .signin-title {
        font-size: 1.8rem;
    }
}

/* Animation */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.signin-container {
    animation: fadeIn 0.5s ease-out forwards;
}