:root {
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --accent-color: #38bdf8;
    --accent-hover: #0284c7;
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --border-color: #334155;
    --error-bg: rgba(239, 68, 68, 0.1);
    --error-border: #ef4444;
    --error-text: #fca5a5;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

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

header {
    background-color: rgba(30, 41, 59, 0.8);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo span {
    color: var(--text-main);
}

nav a {
    color: var(--text-muted);
    text-decoration: none;
    margin-left: 1.5rem;
    transition: color 0.2s;
}

nav a:hover {
    color: var(--accent-color);
}

.main-container {
    max-width: 1100px;
    margin: 2rem auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 2rem;
    flex: 1;
}

.article-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    transition: border-color 0.2s;
}

.article-card:hover {
    border-color: #475569;
}

.article-tag {
    display: inline-block;
    background: rgba(56, 189, 248, 0.1);
    color: var(--accent-color);
    padding: 0.2rem 0.6rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 0.8rem;
}

.article-title {
    font-size: 1.4rem;
    margin-bottom: 0.5rem;
    color: var(--text-main);
}

.article-meta {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
}

.article-excerpt {
    color: #cbd5e1;
    font-size: 0.95rem;
}

.sidebar {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.login-box {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
    position: sticky;
    top: 5rem;
}

.login-box h3 {
    margin-bottom: 0.5rem;
    font-size: 1.2rem;
}

.login-box p {
    color: var(--text-muted);
    font-size: 0.85rem;
    margin-bottom: 1.2rem;
}

.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    font-size: 0.85rem;
    font-weight: 500;
    margin-bottom: 0.4rem;
    color: var(--text-muted);
}

.form-group input {
    width: 100%;
    padding: 0.65rem 0.8rem;
    background: #0f172a;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-main);
    font-size: 0.9rem;
    outline: none;
    transition: border-color 0.2s;
}

.form-group input:focus {
    border-color: var(--accent-color);
}

.btn-submit {
    width: 100%;
    padding: 0.75rem;
    background: var(--accent-color);
    color: #0f172a;
    font-weight: 600;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: background-color 0.2s;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
}

.btn-submit:hover {
    background: var(--accent-hover);
    color: #ffffff;
}

.error-message {
    display: none;
    background: var(--error-bg);
    border: 1px solid var(--error-border);
    color: var(--error-text);
    padding: 0.75rem;
    border-radius: 6px;
    font-size: 0.85rem;
    margin-bottom: 1rem;
    animation: shake 0.3s ease-in-out;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    20%, 60% { transform: translateX(-5px); }
    40%, 80% { transform: translateX(5px); }
}

.spinner {
    display: none;
    width: 16px;
    height: 16px;
    border: 2px solid rgba(15, 23, 42, 0.3);
    border-radius: 50%;
    border-top-color: #0f172a;
    animation: spin 0.8s linear infinite;
}

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

footer {
    text-align: center;
    padding: 2rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-muted);
    font-size: 0.85rem;
    margin-top: auto;
}

@media (max-width: 768px) {
    .main-container {
        grid-template-columns: 1fr;
    }
}