/* File: /TaskHub/frontend/css/styles.css */
* { margin: 0; padding: 0; box-sizing: border-box; }

body { 
    font-family: 'Inter', -apple-system, sans-serif; 
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
}

.app { min-height: 100vh; display: flex; flex-direction: column; }

.header { 
    background: rgba(255,255,255,0.95); 
    backdrop-filter: blur(10px);
    padding: 1.5rem 2rem; 
    box-shadow: 0 2px 20px rgba(0,0,0,0.1);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo { font-size: 24px; font-weight: 700; color: #667eea; }

.container { 
    max-width: 1600px; 
    margin: 2rem auto; 
    padding: 0 2rem; 
    flex: 1;
    width: 100%;
}

.stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: white;
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.08);
}

.stat-value { font-size: 32px; font-weight: 700; color: #1a202c; }
.stat-label { color: #718096; margin-top: 0.5rem; font-size: 14px; }

.board { 
    display: grid; 
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.column { 
    background: white;
    border-radius: 16px;
    padding: 1.5rem;
    box-shadow: 0 8px 30px rgba(0,0,0,0.12);
    min-height: 600px;
}

.column-header { 
    font-weight: 700; 
    font-size: 18px;
    margin-bottom: 1.5rem; 
    padding-bottom: 1rem;
    border-bottom: 2px solid #f7fafc;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.task-card { 
    background: #f8fafc;
    padding: 1.5rem;
    margin-bottom: 1rem;
    border-radius: 12px;
    cursor: pointer;
    border: 2px solid transparent;
    transition: all 0.2s;
}

.task-card:hover { 
    border-color: #667eea;
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(102,126,234,0.15);
}

.task-title { 
    font-weight: 600; 
    font-size: 16px;
    margin-bottom: 0.5rem;
    color: #1a202c;
}

.task-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 1rem;
    font-size: 12px;
    color: #718096;
}

.grade { 
    display: inline-block; 
    padding: 4px 12px; 
    border-radius: 20px; 
    font-size: 11px; 
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.grade-A { background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%); color: white; }
.grade-B { background: linear-gradient(135deg, #fa709a 0%, #fee140 100%); color: white; }
.grade-C { background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%); color: white; }
.grade-D { background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%); color: #555; }

.btn { 
    padding: 0.75rem 1.5rem; 
    border: none; 
    border-radius: 10px; 
    cursor: pointer; 
    font-weight: 600;
    transition: all 0.2s;
    font-size: 14px;
}

.btn-primary { 
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white; 
    box-shadow: 0 4px 15px rgba(102,126,234,0.4);
}

.btn-primary:hover { 
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102,126,234,0.5);
}

.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0,0,0,0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(5px);
    z-index: 1000;
    padding: 1rem;
}

.modal-content {
    background: white;
    padding: 2.5rem;
    border-radius: 20px;
    width: 90%;
    max-width: 600px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
    max-height: 90vh;
    overflow-y: auto;
}

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

.form-label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #2d3748;
}

.form-input, .form-select, .form-textarea {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    font-family: 'Inter', sans-serif;
    font-size: 14px;
    transition: all 0.2s;
}

.form-input:focus, .form-select:focus, .form-textarea:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102,126,234,0.1);
}

.badge { 
    display: inline-block;
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 11px;
    font-weight: 600;
    background: #edf2f7;
    color: #4a5568;
}

.login-container {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
}

.login-box {
    background: white;
    padding: 3rem;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
    width: 90%;
    max-width: 400px;
}

.login-title {
    font-size: 28px;
    font-weight: 700;
    color: #667eea;
    text-align: center;
    margin-bottom: 2rem;
}

/* 모바일 */
@media (max-width: 768px) {
    .header { padding: 1rem; flex-direction: column; gap: 1rem; }
    .logo { font-size: 20px; }
    .container { padding: 0 1rem; margin: 1rem auto; }
    .stats { grid-template-columns: repeat(2, 1fr); gap: 1rem; margin-bottom: 1rem; }
    .stat-card { padding: 1rem; }
    .stat-value { font-size: 24px; }
    .stat-label { font-size: 12px; }
    .board { grid-template-columns: 1fr; gap: 1rem; }
    .column { min-height: auto; padding: 1rem; }
    .column-header { font-size: 16px; }
    .task-card { padding: 1rem; }
    .task-title { font-size: 14px; }
    .modal-content { padding: 1.5rem; width: 95%; }
    .btn { padding: 0.6rem 1rem; font-size: 13px; width: 100%; }
    .login-box { padding: 2rem 1.5rem; width: 95%; }
}


/* Tab Buttons */
.tab-button {
    background: none;
    border: none;
    padding: 0.75rem 1.5rem;
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    color: #718096;
    border-bottom: 3px solid transparent;
    transition: all 0.2s;
}

.tab-button:hover {
    color: #2d3748;
    background: #f7fafc;
}

.tab-button.active {
    color: #667eea;
    border-bottom-color: #667eea;
}